Use `rx' in Tramp where possible

* lisp/net/tramp.el:
* lisp/net/tramp-adb.el:
* lisp/net/tramp-archive.el:
* lisp/net/tramp-cache.el:
* lisp/net/tramp-cmds.el:
* lisp/net/tramp-compat.el:
* lisp/net/tramp-crypt.el:
* lisp/net/tramp-ftp.el:
* lisp/net/tramp-fuse.el:
* lisp/net/tramp-gvfs.el:
* lisp/net/tramp-integration.el:
* lisp/net/tramp-rclone.el:
* lisp/net/tramp-sh.el:
* lisp/net/tramp-smb.el:
* lisp/net/tramp-sudoedit.el: Use `rx' where possible.

* lisp/net/tramp-adb.el (tramp-adb-handle-set-file-times):
Use `eval-when-compile'.
(tramp-adb-maybe-open-connection): Use file-property for "/".  Use
`eval-when-compile'.

* lisp/net/tramp-cmds.el (mm-7bit-chars): Declare.
(tramp-reporter-dump-variable): Simplify point movement.

* lisp/net/tramp-gvfs.el (tramp-dbus-function): Fix typo.
(tramp-zeroconf-parse-device-names): Use `tramp-prefix-port-format'.

* lisp/net/tramp-sh.el (tramp-open-shell, tramp-find-shell):
Use `eval-when-compile'.  Improve sanity check.

* lisp/net/tramp.el (tramp-prefix-format, tramp-prefix-regexp)
(tramp-method-regexp, tramp-postfix-method-format)
(tramp-postfix-method-regexp, tramp-prefix-ipv6-format)
(tramp-prefix-ipv6-regexp, tramp-postfix-ipv6-format)
(tramp-postfix-ipv6-regexp, tramp-postfix-host-format)
(tramp-postfix-host-regexp, tramp-remote-file-name-spec-regexp)
(tramp-file-name-structure, tramp-file-name-regexp)
(tramp-completion-method-regexp)
(tramp-completion-file-name-regexp): Declare.
(tramp-set-syntax): Set also `tramp-completion-method-regexp'.
(tramp-volume-letter-regexp, tramp-completion-method-regexp-alist):
New defconsts.
(tramp-build-completion-method-regexp): New defun.
(tramp-completion-method-regexp): New defvar.
(tramp-completion-file-name-regexp-default)
(tramp-completion-file-name-regexp-simplified)
(tramp-completion-file-name-regexp-separate)
(tramp-completion-file-name-regexp-alist): Remove.
(tramp-build-completion-file-name-regexp): Rwrite.
(tramp-make-tramp-file-name): Use `tramp-archive-method'.
(tramp-handle-file-directory-p): Ignore errors.
(tramp-handle-find-backup-file-name, tramp-handle-lock-file)
(tramp-handle-make-auto-save-file-name): Use `eval-when-compile'.

* test/lisp/net/tramp-archive-tests.el:
* test/lisp/net/tramp-tests.el: Use `rx' where possible.
(tramp-test01-file-name-syntax): Adapt test.

18 files changed, 996 insertions, 901 deletions

diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index be231fcba63..b38b908edb0 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -55,7 +55,7 @@ It is used for TCP/IP devices."
 (defconst tramp-adb-method "adb"
   "When this method name is used, forward all calls to Android Debug Bridge.")
 
-(defcustom tramp-adb-prompt "^[^#$\n\r]*[#$][[:space:]]"
+(defcustom tramp-adb-prompt (rx bol (* (not (any "#$\n\r"))) (any "#$") space)
   "Regexp used as prompt in almquist shell."
   :type 'regexp
   :version "28.1"
@@ -63,31 +63,28 @@ It is used for TCP/IP devices."
 
 (eval-and-compile
   (defconst tramp-adb-ls-date-year-regexp
-    "[[:digit:]]\\{4\\}-[[:digit:]]\\{2\\}-[[:digit:]]\\{2\\}"
+    (rx (= 4 digit) "-" (= 2 digit) "-" (= 2 digit))
     "Regexp for date year format in ls output."))
 
 (eval-and-compile
-  (defconst tramp-adb-ls-date-time-regexp
-    "[[:digit:]]\\{2\\}:[[:digit:]]\\{2\\}"
+  (defconst tramp-adb-ls-date-time-regexp (rx (= 2 digit) ":" (= 2 digit))
   "Regexp for date time format in ls output."))
 
 (defconst tramp-adb-ls-date-regexp
-  (concat
-   "[[:space:]]" tramp-adb-ls-date-year-regexp
-   "[[:space:]]" tramp-adb-ls-date-time-regexp
-   "[[:space:]]")
+  (rx space (regexp tramp-adb-ls-date-year-regexp)
+      space (regexp tramp-adb-ls-date-time-regexp)
+      space)
   "Regexp for date format in ls output.")
 
 (defconst tramp-adb-ls-toolbox-regexp
-  (concat
-   "^[[:space:]]*\\([-.[:alpha:]]+\\)"	; \1 permissions
-   "\\(?:[[:space:]]+[[:digit:]]+\\)?"	; links (Android 7/toybox)
-   "[[:space:]]*\\([^[:space:]]+\\)"	; \2 username
-   "[[:space:]]+\\([^[:space:]]+\\)"	; \3 group
-   "[[:space:]]+\\([[:digit:]]+\\)"	; \4 size
-   "[[:space:]]+\\(" tramp-adb-ls-date-year-regexp
-   "[[:space:]]" tramp-adb-ls-date-time-regexp "\\)" ; \5 date
-   "[[:space:]]\\(.*\\)$")		; \6 filename
+  (rx bol (* space) (group (+ (any ".-" alpha)))		; \1 permissions
+      (? (+ space) (+ digit))			      ; links (Android 7/toybox)
+      (* space) (group (+ (not space)))				; \2 username
+      (+ space) (group (+ (not space)))				; \3 group
+      (+ space) (group (+ digit))				; \4 size
+      (+ space) (group (regexp tramp-adb-ls-date-year-regexp)
+		 space (regexp tramp-adb-ls-date-time-regexp))	; \5 date
+      space (group (* nonl)) eol)				; \6 filename
   "Regexp for ls output.")
 
 ;;;###tramp-autoload
@@ -220,7 +217,8 @@ arguments to pass to the OPERATION."
   (delq nil
 	(mapcar
 	 (lambda (line)
-	   (when (string-match "^\\(\\S-+\\)[[:space:]]+device$" line)
+	   (when (string-match
+		  (rx bol (group (+ (not space))) (+ space) "device" eol) line)
 	     ;; Replace ":" by "#".
 	     `(nil ,(tramp-compat-string-replace
 		     ":" tramp-prefix-port-format (match-string 1 line)))))
@@ -237,10 +235,10 @@ arguments to pass to the OPERATION."
 	(goto-char (point-min))
 	(forward-line)
 	(when (looking-at
-	       (concat "[[:space:]]*[^[:space:]]+"
-		       "[[:space:]]+\\([[:digit:]]+\\)"
-		       "[[:space:]]+\\([[:digit:]]+\\)"
-		       "[[:space:]]+\\([[:digit:]]+\\)"))
+	       (rx (* space) (+ (not space))
+		   (+ space) (group (+ digit))
+		   (+ space) (group (+ digit))
+		   (+ space) (group (+ digit))))
 	  ;; The values are given as 1k numbers, so we must change
 	  ;; them to number of bytes.
 	  (list (* 1024 (string-to-number (match-string 1)))
@@ -280,10 +278,10 @@ arguments to pass to the OPERATION."
 	       (name (match-string 6))
 	       (symlink-target
 		(and is-symlink
-		     (cadr (split-string name "\\( -> \\|\n\\)")))))
+		     (cadr (split-string name (rx (group (| " -> " "\n"))))))))
 	  (push (list
 		 (if is-symlink
-		     (car (split-string name "\\( -> \\|\n\\)"))
+		     (car (split-string name (rx (group (| " -> " "\n")))))
 		   name)
 		 (or is-dir symlink-target)
 		 1     ;link-count
@@ -315,7 +313,7 @@ arguments to pass to the OPERATION."
 		       (tramp-shell-quote-argument localname)))
 	;; We insert also filename/. and filename/.., because "ls"
 	;; doesn't on some file systems, like "sdcard".
-	(unless (re-search-backward "\\.$" nil t)
+	(unless (re-search-backward (rx "." eol) nil t)
 	  (narrow-to-region (point-max) (point-max))
 	  (tramp-adb-send-command
 	   v (format "%s -d -a -l %s %s | cat"
@@ -325,9 +323,8 @@ arguments to pass to the OPERATION."
 		     (tramp-shell-quote-argument
 		      (tramp-compat-file-name-concat localname ".."))))
 	  (tramp-compat-replace-regexp-in-region
-	   (regexp-quote
-	    (tramp-compat-file-name-unquote
-	     (file-name-as-directory localname)))
+	   (rx (literal (tramp-compat-file-name-unquote
+			 (file-name-as-directory localname))))
 	   "" (point-min))
 	  (widen)))
       (tramp-adb-sh-fix-ls-output)
@@ -365,16 +362,12 @@ Emacs dired can't find files."
     (goto-char (point-min))
     (while
 	(search-forward-regexp
-	 (eval-when-compile
-	   (concat
-	    "[[:space:]]"
-	    "\\([[:space:]]" tramp-adb-ls-date-year-regexp "[[:space:]]\\)"))
+	 (rx space (group space (regexp tramp-adb-ls-date-year-regexp) space))
 	 nil t)
       (replace-match "0\\1" "\\1" nil)
       ;; Insert missing "/".
       (when (looking-at-p
-	     (eval-when-compile
-	       (concat tramp-adb-ls-date-time-regexp "[[:space:]]+$")))
+	     (rx (regexp tramp-adb-ls-date-time-regexp) (+ space) eol))
 	(end-of-line)
 	(insert "/")))
     ;; Sort entries.
@@ -472,7 +465,8 @@ Emacs dired can't find files."
 	    (delq
 	     nil
 	     (mapcar
-	      (lambda (l) (and (not (string-match-p "^[[:space:]]*$" l)) l))
+	      (lambda (l)
+		(and (not (string-match-p (rx bol (* space) eol) l)) l))
 	      (split-string (buffer-string) "\n")))))))))))
 
 (defun tramp-adb-handle-file-local-copy (filename)
@@ -566,9 +560,10 @@ Emacs dired can't find files."
       ;; (introduced in POSIX.1-2008) fails.
       (tramp-adb-send-command-and-check
        v (format
-	  (concat "touch -d %s %s %s 2>%s || "
-		  "touch -d %s %s %s 2>%s || "
-		  "touch -t %s %s %s")
+	  (eval-when-compile
+	    (concat "touch -d %s %s %s 2>%s || "
+		    "touch -d %s %s %s 2>%s || "
+		    "touch -t %s %s %s"))
 	  (format-time-string "%Y-%m-%dT%H:%M:%S.%NZ" time t)
 	  nofollow quoted-name (tramp-get-remote-null-device v)
 	  (format-time-string "%Y-%m-%dT%H:%M:%S" time t)
@@ -723,10 +718,9 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
       (setcar result 0)
       (dolist (line signals)
 	(when (string-match
-	       (concat
-		"^[[:space:]]*\\([[:digit:]]+\\)"
-		"[[:space:]]+\\S-+[[:space:]]+"
-		"\\([[:alpha:]].*\\)$")
+	       (rx bol (* space) (group (+ digit))
+		   (+ space) (+ (not space))
+		   (+ space) (group alpha (* nonl)) eol)
 	       line)
 	  (setcar
 	   (nthcdr (string-to-number (match-string 1 line)) result)
@@ -924,7 +918,7 @@ implementation will be used."
 		 (i 0)
 		 p)
 
-	    (when (string-match-p "[[:multibyte:]]" command)
+	    (when (string-match-p (rx multibyte) command)
 	      (tramp-error
 	       v 'file-error "Cannot apply multi-byte command `%s'" command))
 
@@ -997,7 +991,7 @@ implementation will be used."
 			      (while
 				  (progn
 				    (goto-char (point-min))
-				    (not (re-search-forward "[\n]" nil t)))
+				    (not (search-forward "\n" nil t)))
 			        (tramp-accept-process-output p 0))
 			      (delete-region (point-min) (point)))
 			    ;; Provide error buffer.  This shows only
@@ -1125,7 +1119,7 @@ error and non-nil on success."
 
 (defun tramp-adb-send-command (vec command &optional neveropen nooutput)
   "Send the COMMAND to connection VEC."
-  (if (string-match-p "[[:multibyte:]]" command)
+  (if (string-match-p (rx multibyte) command)
       ;; Multibyte codepoints with four bytes are not supported at
       ;; least by toybox.
 
@@ -1149,12 +1143,12 @@ error and non-nil on success."
 	  ;; We can't use stty to disable echo of command.  stty is said
 	  ;; to be added to toybox 0.7.6.  busybox shall have it, but this
 	  ;; isn't used any longer for Android.
-	  (delete-matching-lines (regexp-quote command))
+	  (delete-matching-lines (rx (literal command)))
 	  ;; When the local machine is W32, there are still trailing ^M.
 	  ;; There must be a better solution by setting the correct coding
 	  ;; system, but this requires changes in core Tramp.
 	  (goto-char (point-min))
-	  (while (re-search-forward "\r+$" nil t)
+	  (while (re-search-forward (rx (+ "\r") eol) nil t)
 	    (replace-match "" nil nil)))))))
 
 (defun tramp-adb-send-command-and-check (vec command &optional exit-status)
@@ -1170,7 +1164,7 @@ the exit status."
 	   (format "%s; echo tramp_exit_status $?" command)
 	 "echo tramp_exit_status $?"))
   (with-current-buffer (tramp-get-connection-buffer vec)
-    (unless (tramp-search-regexp "tramp_exit_status [[:digit:]]+")
+    (unless (tramp-search-regexp (rx "tramp_exit_status " (+ digit)))
       (tramp-error
        vec 'file-error "Couldn't find exit status of `%s'" command))
     (skip-chars-forward "^ ")
@@ -1198,7 +1192,7 @@ FMT and ARGS are passed to `error'."
 	  (let ((inhibit-read-only t))
 	    (goto-char (point-min))
 	    ;; ADB terminal sends "^H" sequences.
-            (when (re-search-forward "<\b+" (line-end-position) t)
+	    (when (re-search-forward (rx "<" (+ "\b")) (line-end-position) t)
 	      (forward-line 1)
 	      (delete-region (point-min) (point)))
 	    ;; Delete the prompt.
@@ -1232,7 +1226,7 @@ connection if a previous connection has died for some reason."
     ;; Maybe we know already that "su" is not supported.  We cannot
     ;; use a connection property, because we have not checked yet
     ;; whether it is still the same device.
-    (when (and user (not (tramp-get-file-property vec "" "su-command-p" t)))
+    (when (and user (not (tramp-get-file-property vec "/" "su-command-p" t)))
       (tramp-error vec 'file-error "Cannot switch to user `%s'" user))
 
     (unless (process-live-p p)
@@ -1272,7 +1266,7 @@ connection if a previous connection has died for some reason."
 
 	    ;; Change prompt.
 	    (tramp-set-connection-property
-	     p "prompt" (regexp-quote (format "///%s#$" prompt)))
+	     p "prompt" (rx "///" (literal prompt) "#$"))
 	    (tramp-adb-send-command
 	     vec (format "PS1=\"///\"\"%s\"\"#$\"" prompt))
 
@@ -1290,10 +1284,11 @@ connection if a previous connection has died for some reason."
 	    (tramp-message vec 5 "Checking system information")
 	    (tramp-adb-send-command
 	     vec
-	     (concat
-	      "echo \\\"`getprop ro.product.model` "
-	      "`getprop ro.product.version` "
-	      "`getprop ro.build.version.release`\\\""))
+	     (eval-when-compile
+	       (concat
+		"echo \\\"`getprop ro.product.model` "
+		"`getprop ro.product.version` "
+		"`getprop ro.build.version.release`\\\"")))
 	    (let ((old-getprop (tramp-get-connection-property vec "getprop"))
 		  (new-getprop
 		   (tramp-set-connection-property
@@ -1317,7 +1312,7 @@ connection if a previous connection has died for some reason."
 	      (unless (tramp-adb-send-command-and-check vec nil)
 		(delete-process p)
 		;; Do not flush, we need the nil value.
-		(tramp-set-file-property vec "" "su-command-p" nil)
+		(tramp-set-file-property vec "/" "su-command-p" nil)
 		(tramp-error
 		 vec 'file-error "Cannot switch to user `%s'" user)))
 
diff --git a/lisp/net/tramp-archive.el b/lisp/net/tramp-archive.el
index 548999ca1d2..0d931b42da4 100644
--- a/lisp/net/tramp-archive.el
+++ b/lisp/net/tramp-archive.el
@@ -168,7 +168,8 @@
 It must be supported by libarchive(3).")
 
 ;; <https://unix-memo.readthedocs.io/en/latest/vfs.html>
-;;    read and write: tar, cpio, pax , gzip , zip, bzip2, xz, lzip, lzma, ar, mtree, iso9660, compress.
+;;    read and write: tar, cpio, pax , gzip , zip, bzip2, xz, lzip,
+;;                    lzma, ar, mtree, iso9660, compress.
 ;;    read only: 7-Zip, mtree, xar, lha/lzh, rar, microsoft cab.
 
 ;;;###autoload
@@ -183,14 +184,17 @@ It must be supported by libarchive(3).")
 ;;;###autoload
 (progn (defmacro tramp-archive-autoload-file-name-regexp ()
   "Regular expression matching archive file names."
-  '(concat
-    "\\`" "\\(" ".+" "\\."
-      ;; Default suffixes ...
-      (regexp-opt tramp-archive-suffixes)
-      ;; ... with compression.
-      "\\(?:" "\\." (regexp-opt tramp-archive-compression-suffixes) "\\)*"
-    "\\)" ;; \1
-    "\\(" "/" ".*" "\\)" "\\'"))) ;; \2
+  '(rx bos
+       ;; \1
+       (group
+	(+ nonl)
+	;; Default suffixes ...
+	"." (regexp (regexp-opt tramp-archive-suffixes))
+	;; ... with compression.
+	(? "." (regexp (regexp-opt tramp-archive-compression-suffixes))))
+       ;; \2
+       (group "/" (* nonl))
+       eos)))
 
 (put #'tramp-archive-autoload-file-name-regexp 'tramp-autoload t)
 
diff --git a/lisp/net/tramp-cache.el b/lisp/net/tramp-cache.el
index 289df2f9aad..6a3e60f7037 100644
--- a/lisp/net/tramp-cache.el
+++ b/lisp/net/tramp-cache.el
@@ -226,7 +226,8 @@ Return VALUE."
       (setq key (tramp-file-name-unify key file))
       (dolist (property (hash-table-keys (tramp-get-hash-table key)))
 	(when (string-match-p
-	       "^\\(directory-\\|file-name-all-completions\\|file-entries\\)"
+	       (rx
+		bos (| "directory-" "file-name-all-completions" "file-entries"))
 	       property)
 	  (tramp-flush-file-property key file property))))))
 
@@ -277,7 +278,7 @@ Remove also properties of all files in subdirectories."
 This is suppressed for temporary buffers."
   (save-match-data
     (unless (or (null (buffer-name))
-		(string-match-p "^\\( \\|\\*\\)" (buffer-name)))
+		(string-match-p (rx bos (| " " "*")) (buffer-name)))
       (let ((bfn (if (stringp (buffer-file-name))
 		     (buffer-file-name)
 		   default-directory))
diff --git a/lisp/net/tramp-cmds.el b/lisp/net/tramp-cmds.el
index b2a68fc5eba..a7ac1352665 100644
--- a/lisp/net/tramp-cmds.el
+++ b/lisp/net/tramp-cmds.el
@@ -34,6 +34,7 @@
 (declare-function mml-mode "mml")
 (declare-function mml-insert-empty-tag "mml")
 (declare-function reporter-dump-variable "reporter")
+(defvar mm-7bit-chars)
 (defvar reporter-eval-buffer)
 (defvar reporter-prompt-for-summary-p)
 
@@ -502,7 +503,7 @@ This is needed if there are compatibility problems."
       ((dir (tramp-compat-funcall
 	     'package-desc-dir
 	     (car (alist-get 'tramp (bound-and-true-p package-alist))))))
-    (dolist (elc (directory-files dir 'full "\\.elc\\'"))
+    (dolist (elc (directory-files dir 'full (rx ".elc" eos)))
       (delete-file elc))
     (with-current-buffer (get-buffer-create byte-compile-log-buffer)
       (let ((inhibit-read-only t))
@@ -604,7 +605,7 @@ buffer in your bug report.
       ;; There are non-7bit characters to be masked.
       (when (and (stringp val)
 		 (string-match-p
-		  (concat "[^" (bound-and-true-p mm-7bit-chars) "]") val))
+		  (rx-to-string `(not (any ,mm-7bit-chars))) val))
 	(with-current-buffer reporter-eval-buffer
 	  (set varsym
 	       `(decode-coding-string
@@ -613,20 +614,21 @@ buffer in your bug report.
 		 'raw-text)))))
 
     ;; Dump variable.
-    (reporter-dump-variable varsym mailbuf)
+    (goto-char (point-max))
+    (save-excursion
+      (reporter-dump-variable varsym mailbuf))
 
     (unless (hash-table-p val)
       ;; Remove string quotation.
-      (forward-line -1)
       (when (looking-at
-	     (concat "\\(^.*\\)" "\""                       ;; \1 "
-		     "\\((base64-decode-string \\)" "\\\\"  ;; \2 \
-		     "\\(\".*\\)" "\\\\"                    ;; \3 \
-		     "\\(\")\\)" "\"$"))                    ;; \4 "
+	     (rx bol (group (* anychar)) "\""          ;; \1 "
+		 (group "(base64-decode-string ") "\\" ;; \2 \
+		 (group "\"" (* anychar)) "\\"         ;; \3 \
+		 (group "\")") "\"" eol))              ;; \4 "
 	(replace-match "\\1\\2\\3\\4")
 	(beginning-of-line)
-	(insert " ;; Variable encoded due to non-printable characters.\n"))
-      (forward-line 1))
+	(insert " ;; Variable encoded due to non-printable characters.\n")))
+    (goto-char (point-max))
 
     ;; Reset VARSYM to old value.
     (with-current-buffer reporter-eval-buffer
@@ -656,21 +658,27 @@ buffer in your bug report.
 	(erase-buffer)
 	(insert (format "\n;; %s\n(setq-local\n" (buffer-name buffer)))
 	(lisp-indent-line)
-	(dolist
-	    (varsym
-	     (sort
-	      (append
-	       (mapcar
-		#'intern
-		(all-completions "tramp-" (buffer-local-variables buffer)))
-	       ;; Non-tramp variables of interest.
-	       '(connection-local-variables-alist default-directory))
-	      #'string<))
-	    (reporter-dump-variable varsym elbuf))
+	(dolist (varsym
+		 (sort
+		  (append
+		   (mapcar
+		    #'intern
+		    (all-completions "tramp-" (buffer-local-variables buffer)))
+		   ;; Non-tramp variables of interest.
+		   '(connection-local-variables-alist default-directory))
+		  #'string<))
+	  (reporter-dump-variable varsym elbuf))
 	(lisp-indent-line)
 	(insert ")\n"))
       (insert-buffer-substring elbuf)))
 
+  ;; Beautify encoded values.
+  (goto-char (point-min))
+  (while (re-search-forward
+	  (rx "'" (group "(decode-coding-string")) nil 'noerror)
+    (replace-match "\\1"))
+  (goto-char (point-max))
+
   ;; Dump load-path shadows.
   (insert "\nload-path shadows:\n==================\n")
   (ignore-errors
@@ -683,7 +691,7 @@ buffer in your bug report.
 	 (eq major-mode 'message-mode)
 	 (bound-and-true-p mml-mode))
 
-    (let ((tramp-buf-regexp "\\*\\(debug \\)?tramp/")
+    (let ((tramp-buf-regexp (rx "*" (? "debug ") "tramp/"))
 	  (buffer-list (tramp-list-tramp-buffers))
 	  (curbuf (current-buffer)))
 
@@ -694,7 +702,7 @@ buffer in your bug report.
 	(setq buffer-read-only nil)
 	(goto-char (point-min))
 	(while (not (eobp))
-          (if (re-search-forward tramp-buf-regexp (line-end-position) t)
+	  (if (re-search-forward tramp-buf-regexp (line-end-position) t)
 	      (forward-line 1)
 	    (forward-line 0)
 	    (let ((start (point)))
diff --git a/lisp/net/tramp-compat.el b/lisp/net/tramp-compat.el
index 203d3ede98f..b7c0a3113ee 100644
--- a/lisp/net/tramp-compat.el
+++ b/lisp/net/tramp-compat.el
@@ -237,7 +237,7 @@ CONDITION can also be a list of error conditions."
     (lambda (from-string to-string in-string)
       (let (case-fold-search)
         (replace-regexp-in-string
-         (regexp-quote from-string) to-string in-string t t)))))
+         (rx (literal from-string)) to-string in-string t t)))))
 
 ;; Function `string-search' is new in Emacs 28.1.
 (defalias 'tramp-compat-string-search
@@ -245,7 +245,7 @@ CONDITION can also be a list of error conditions."
       #'string-search
     (lambda (needle haystack &optional start-pos)
       (let (case-fold-search)
-        (string-match-p (regexp-quote needle) haystack start-pos)))))
+        (string-match-p (rx (literal needle)) haystack start-pos)))))
 
 ;; Function `make-lock-file-name' is new in Emacs 28.1.
 (defalias 'tramp-compat-make-lock-file-name
diff --git a/lisp/net/tramp-crypt.el b/lisp/net/tramp-crypt.el
index 657437b283c..e7bb1ebe338 100644
--- a/lisp/net/tramp-crypt.el
+++ b/lisp/net/tramp-crypt.el
@@ -426,7 +426,7 @@ Otherwise, return NAME."
        (if (directory-name-p name) #'file-name-as-directory #'identity)
        (concat
 	dir
-	(unless (string-match-p (rx (seq bos (opt "/") eos)) localname)
+	(unless (string-match-p (rx bos (? "/") eos) localname)
 	  (with-tramp-file-property
 	      crypt-vec localname (concat (symbol-name op) "-file-name")
 	    (unless (tramp-crypt-send-command
@@ -437,7 +437,7 @@ Otherwise, return NAME."
 	       (if (eq op 'encrypt) "Encoding" "Decoding") name))
 	    (with-current-buffer (tramp-get-connection-buffer crypt-vec)
 	      (goto-char (point-min))
-              (buffer-substring (point-min) (line-end-position)))))))
+	      (buffer-substring (point-min) (line-end-position)))))))
     ;; Nothing to do.
     name))
 
@@ -554,7 +554,7 @@ localname."
 (defun tramp-crypt-handle-access-file (filename string)
   "Like `access-file' for Tramp files."
   (let* ((encrypt-filename (tramp-crypt-encrypt-file-name filename))
-	 (encrypt-regexp (concat (regexp-quote encrypt-filename) "\\'"))
+	 (encrypt-regexp (rx (literal encrypt-filename) eos))
 	 tramp-crypt-enabled)
     (condition-case err
 	(access-file encrypt-filename string)
@@ -706,7 +706,7 @@ absolute file names."
       (mapcar
        (lambda (x)
 	 (replace-regexp-in-string
-	  (concat "^" (regexp-quote directory)) ""
+	  (rx bos (literal directory)) ""
 	  (tramp-crypt-decrypt-file-name x)))
        (directory-files (tramp-crypt-encrypt-file-name directory) 'full)))))
 
diff --git a/lisp/net/tramp-ftp.el b/lisp/net/tramp-ftp.el
index dd7e0f9f342..ad736256cab 100644
--- a/lisp/net/tramp-ftp.el
+++ b/lisp/net/tramp-ftp.el
@@ -97,9 +97,9 @@ present for backward compatibility."
 
  ;; Add some defaults for `tramp-default-method-alist'.
  (add-to-list 'tramp-default-method-alist
-	      (list "\\`ftp\\." nil tramp-ftp-method))
+	      (list (rx bos "ftp.") nil tramp-ftp-method))
  (add-to-list 'tramp-default-method-alist
-	      (list nil "\\`\\(anonymous\\|ftp\\)\\'" tramp-ftp-method))
+	      (list nil (rx bos (| "anonymous" "ftp") eos) tramp-ftp-method))
 
  ;; Add completion function for FTP method.
  (tramp-set-completion-function
diff --git a/lisp/net/tramp-fuse.el b/lisp/net/tramp-fuse.el
index 486a3cc57b7..4b51af070aa 100644
--- a/lisp/net/tramp-fuse.el
+++ b/lisp/net/tramp-fuse.el
@@ -51,7 +51,7 @@
   "Remove hidden files from FILES."
   (if tramp-fuse-remove-hidden-files
       (cl-remove-if
-       (lambda (x) (and (stringp x) (string-match-p "\\.fuse_hidden" x)))
+       (lambda (x) (and (stringp x) (string-match-p (rx ".fuse_hidden") x)))
        files)
     files))
 
@@ -69,10 +69,10 @@
 	       (tramp-fuse-local-file-name directory))))))))
     (if full
 	;; Massage the result.
-	(let ((local (concat
-		      "^" (regexp-quote
-			   (tramp-fuse-mount-point
-			    (tramp-dissect-file-name directory)))))
+	(let ((local (rx bol
+			 (literal
+			  (tramp-fuse-mount-point
+			   (tramp-dissect-file-name directory)))))
 	      (remote (directory-file-name
 		       (funcall
 			(if (tramp-compat-file-name-quoted-p directory)
@@ -179,8 +179,7 @@ It has the same meaning as `remote-file-name-inhibit-cache'.")
           (tramp-set-file-property
 	   vec "/" "mounted"
            (when (string-match
-	          (format
-                   "^\\(%s\\)\\s-" (regexp-quote (tramp-fuse-mount-spec vec)))
+	          (rx bol (group (literal (tramp-fuse-mount-spec vec))) space)
 	          mount)
              (match-string 1 mount)))))))
 
diff --git a/lisp/net/tramp-gvfs.el b/lisp/net/tramp-gvfs.el
index ca5e959bea5..9060f37ed57 100644
--- a/lisp/net/tramp-gvfs.el
+++ b/lisp/net/tramp-gvfs.el
@@ -410,9 +410,9 @@ It has been changed in GVFS 1.14.")
 ;; </interface>
 
 (defconst tramp-goa-identity-regexp
-  (concat "^" "\\(" tramp-user-regexp "\\)?"
-	  "@" "\\(" tramp-host-regexp "\\)?"
-	  "\\(?:" ":""\\(" tramp-port-regexp "\\)" "\\)?")
+  (rx bol (? (group (regexp tramp-user-regexp)))
+      "@" (? (group (regexp tramp-host-regexp)))
+      (? ":" (group (regexp tramp-port-regexp))))
   "Regexp matching GNOME Online Accounts \"PresentationIdentity\" property.")
 
 (defconst tramp-goa-interface-mail "org.gnome.OnlineAccounts.Mail"
@@ -712,13 +712,13 @@ It has been changed in GVFS 1.14.")
 
 (eval-and-compile
   (defconst tramp-gvfs-file-attributes-with-gvfs-ls-regexp
-    (concat "[[:blank:]]" (regexp-opt tramp-gvfs-file-attributes t) "=\\(.+?\\)")
+    (rx blank (group (regexp (regexp-opt tramp-gvfs-file-attributes)))
+	"=" (group (+? nonl)))
     "Regexp to parse GVFS file attributes with `gvfs-ls'."))
 
 (defconst tramp-gvfs-file-attributes-with-gvfs-info-regexp
-  (concat "^[[:blank:]]*"
-	  (regexp-opt tramp-gvfs-file-attributes t)
-	  ":[[:blank:]]+\\(.*\\)$")
+  (rx bol (* blank) (group (regexp (regexp-opt tramp-gvfs-file-attributes)))
+      ":" (+ blank) (group (* nonl)) eol)
   "Regexp to parse GVFS file attributes with `gvfs-info'.")
 
 (defconst tramp-gvfs-file-system-attributes
@@ -728,16 +728,16 @@ It has been changed in GVFS 1.14.")
   "GVFS file system attributes.")
 
 (defconst tramp-gvfs-file-system-attributes-regexp
-  (concat "^[[:blank:]]*"
-	  (regexp-opt tramp-gvfs-file-system-attributes t)
-	  ":[[:blank:]]+\\(.*\\)$")
+  (rx bol (* blank)
+      (group (regexp (regexp-opt tramp-gvfs-file-system-attributes)))
+      ":" (+ blank) (group (* nonl)) eol)
   "Regexp to parse GVFS file system attributes with `gvfs-info'.")
 
 (defconst tramp-gvfs-nextcloud-default-prefix "/remote.php/webdav"
   "Default prefix for owncloud / nextcloud methods.")
 
 (defconst tramp-gvfs-nextcloud-default-prefix-regexp
-  (concat (regexp-quote tramp-gvfs-nextcloud-default-prefix) "$")
+  (rx (literal tramp-gvfs-nextcloud-default-prefix) eol)
   "Regexp of default prefix for owncloud / nextcloud methods.")
 
 
@@ -868,7 +868,7 @@ arguments to pass to the OPERATION."
 (defun tramp-gvfs-dbus-string-to-byte-array (string)
   "Like `dbus-string-to-byte-array' but add trailing \\0 if needed."
   (dbus-string-to-byte-array
-   (if (string-match-p "^(aya{sv})" tramp-gvfs-mountlocation-signature)
+   (if (string-match-p (rx bol "(aya{sv})") tramp-gvfs-mountlocation-signature)
        (concat string (string 0)) string)))
 
 (defun tramp-gvfs-dbus-byte-array-to-string (byte-array)
@@ -902,7 +902,7 @@ The call will be traced by Tramp with trace level 6."
   (let (result)
     (tramp-message vec 6 "%s" (cons func args))
     (setq result (apply func args))
-    (tramp-message vec 6 "%s" result(tramp-gvfs-stringify-dbus-message result))
+    (tramp-message vec 6 "%s" (tramp-gvfs-stringify-dbus-message result))
     result))
 
 (put #'tramp-dbus-function 'tramp-suppress-trace t)
@@ -1157,7 +1157,9 @@ file names."
     ;; Dissect NAME.
     (with-parsed-tramp-file-name name nil
       ;; If there is a default location, expand tilde.
-      (when (string-match "\\`~\\([^/]*\\)\\(.*\\)\\'" localname)
+      (when (string-match
+	     (rx bos "~" (group (* (not (any "/")))) (group (* nonl)) eos)
+	      localname)
 	(let ((uname (match-string 1 localname))
 	      (fname (match-string 2 localname))
 	      hname)
@@ -1167,26 +1169,28 @@ file names."
 	    (setq localname (concat hname fname)))))
       ;; Tilde expansion is not possible.
       (when (and (not tramp-tolerate-tilde)
-		 (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname))
+		 (string-prefix-p "~" localname))
 	(tramp-error v 'file-error "Cannot expand tilde in file `%s'" name))
       (unless (tramp-run-real-handler #'file-name-absolute-p (list localname))
 	(setq localname (concat "/" localname)))
       ;; We do not pass "/..".
-      (if (string-match-p "^\\(afp\\|davs?\\|smb\\)$" method)
-	  (when (string-match "^/[^/]+\\(/\\.\\./?\\)" localname)
+      (if (string-match-p (rx bos (| "afp" (: "dav" (? "s")) "smb") eos) method)
+	  (when (string-match
+		 (rx bos "/" (+ (not (any "/"))) (group "/.." (? "/")))
+		 localname)
 	    (setq localname (replace-match "/" t t localname 1)))
-	(when (string-match "^/\\.\\./?" localname)
+	(when (string-match (rx bol "/.." (? "/")) localname)
 	  (setq localname (replace-match "/" t t localname))))
       ;; There might be a double slash.  Remove this.
       (while (string-match "//" localname)
 	(setq localname (replace-match "/" t t localname)))
       ;; Do not keep "/..".
-      (when (string-match-p "^/\\.\\.?$" localname)
+      (when (string-match-p (rx bos "/" (** 1 2 ".") eos) localname)
 	(setq localname "/"))
       ;; Do normal `expand-file-name' (this does "/./" and "/../"),
       ;; unless there are tilde characters in file name.
       (tramp-make-tramp-file-name
-       v (if (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname)
+       v (if (string-prefix-p "~" localname)
 	     localname
 	   (tramp-run-real-handler #'expand-file-name (list localname)))))))
 
@@ -1208,20 +1212,20 @@ file names."
 	(with-current-buffer (tramp-get-connection-buffer v)
 	  (goto-char (point-min))
 	  (while (looking-at
-		  (eval-when-compile
-		    (concat "^\\(.+\\)[[:blank:]]"
-			    "\\([[:digit:]]+\\)[[:blank:]]"
-			    "(\\(.+?\\))"
-			    tramp-gvfs-file-attributes-with-gvfs-ls-regexp)))
+		  (rx bol (group (+ nonl)) blank
+		      (group (+ digit)) blank
+		      "(" (group (+? nonl)) ")"
+		      (regexp tramp-gvfs-file-attributes-with-gvfs-ls-regexp)))
 	    (let ((item (list (cons "type" (match-string 3))
 			      (cons "standard::size" (match-string 2))
 			      (cons "name" (match-string 1)))))
 	      (goto-char (1+ (match-end 3)))
 	      (while (looking-at
-		      (concat
-		       tramp-gvfs-file-attributes-with-gvfs-ls-regexp
-		       "\\(" tramp-gvfs-file-attributes-with-gvfs-ls-regexp
-		       "\\|" "$" "\\)"))
+		      (rx (regexp tramp-gvfs-file-attributes-with-gvfs-ls-regexp)
+			  (group
+			   (| (regexp
+			       tramp-gvfs-file-attributes-with-gvfs-ls-regexp)
+			      eol))))
 		(push (cons (match-string 1) (match-string 2)) item)
 		(goto-char (match-end 2)))
 	      ;; Add display name as head.
@@ -1266,8 +1270,10 @@ If FILE-SYSTEM is non-nil, return file system attributes."
   (setq filename (directory-file-name (expand-file-name filename)))
   (with-parsed-tramp-file-name filename nil
     (setq localname (tramp-compat-file-name-unquote localname))
-    (if (or (and (string-match-p "^\\(afp\\|davs?\\|smb\\)$" method)
-		 (string-match-p "^/?\\([^/]+\\)$" localname))
+    (if (or (and (string-match-p
+		  (rx bol (| "afp" (: "dav" (? "s")) "smb") eol) method)
+		 (string-match-p
+		  (rx bol (? "/") (+ (not (any "/"))) eol) localname))
 	    (string-equal localname "/"))
 	(tramp-gvfs-get-root-attributes filename)
       (assoc
@@ -1297,7 +1303,7 @@ If FILE-SYSTEM is non-nil, return file system attributes."
 	      ;; Convert them to multibyte.
 	      (decode-coding-string
 	       (replace-regexp-in-string
-		"\\\\x\\([[:xdigit:]]\\{2\\}\\)"
+		(rx "\\x" (group (= 2 xdigit)))
 		(lambda (x)
 		  (unibyte-string (string-to-number (match-string 1 x) 16)))
 		res-symlink-target)
@@ -1467,7 +1473,7 @@ If FILE-SYSTEM is non-nil, return file system attributes."
   (let* ((events (process-get proc 'events))
 	 (rest-string (process-get proc 'rest-string))
 	 (dd (tramp-get-default-directory (process-buffer proc)))
-	 (ddu (regexp-quote (tramp-gvfs-url-file-name dd))))
+	 (ddu (rx (literal (tramp-gvfs-url-file-name dd)))))
     (when rest-string
       (tramp-message proc 10 "Previous string:\n%s" rest-string))
     (tramp-message proc 6 "%S\n%s" proc string)
@@ -1481,15 +1487,15 @@ If FILE-SYSTEM is non-nil, return file system attributes."
 	          "renamed to" "moved" string))
     ;; https://bugs.launchpad.net/bugs/1742946
     (when
-	(string-match-p "Monitoring not supported\\|No locations given" string)
+	(string-match-p
+	 (rx (| "Monitoring not supported" "No locations given")) string)
       (delete-process proc))
 
     (while (string-match
-	    (eval-when-compile
-	      (concat "^.+:"
-		      "[[:space:]]\\(.+\\):"
-		      "[[:space:]]" (regexp-opt tramp-gio-events t)
-		      "\\([[:space:]]\\(.+\\)\\)?$"))
+	    (rx bol (+ nonl) ":"
+		space (group (+ nonl)) ":"
+		space (group (regexp (regexp-opt tramp-gio-events)))
+		(? (group space (group (+ nonl)))) eol)
 	    string)
 
       (let ((file (match-string 1 string))
@@ -1499,11 +1505,11 @@ If FILE-SYSTEM is non-nil, return file system attributes."
 	;; File names are returned as URL paths.  We must convert them.
 	(when (string-match ddu file)
 	  (setq file (replace-match dd nil nil file)))
-	(while (string-match-p "%\\([[:xdigit:]]\\{2\\}\\)" file)
+	(while (string-match-p (rx "%" (= 2 xdigit)) file)
 	  (setq file (url-unhex-string file)))
 	(when (string-match ddu (or file1 ""))
 	  (setq file1 (replace-match dd nil nil file1)))
-	(while (string-match-p "%\\([[:xdigit:]]\\{2\\}\\)" (or file1 ""))
+	(while (string-match-p (rx "%" (= 2 xdigit)) (or file1 ""))
 	  (setq file1 (url-unhex-string file1)))
 	;; Remove watch when file or directory to be watched is deleted.
 	(when (and (member action '(moved deleted))
@@ -1719,14 +1725,15 @@ ID-FORMAT valid values are `string' and `integer'."
 (defun tramp-gvfs-file-name (object-path)
   "Retrieve file name from D-Bus OBJECT-PATH."
   (dbus-unescape-from-identifier
-   (replace-regexp-in-string "^.*/\\([^/]+\\)$" "\\1" object-path)))
+   (replace-regexp-in-string
+    (rx bol (* nonl) "/" (+ (not (any "/"))) eol) "\\1" object-path)))
 
 (defun tramp-gvfs-url-host (url)
   "Return the host name part of URL, a string.
 We cannot use `url-host', because `url-generic-parse-url' returns
 a downcased host name only."
   (and (stringp url)
-       (string-match "^[[:alnum:]]+://\\([^/:]+\\)" url)
+       (string-match (rx bol (+ alnum) "://" (group (+ (not (any "/:"))))) url)
        (match-string 1 url)))
 
 
@@ -1739,7 +1746,8 @@ a downcased host name only."
 	 (pw-prompt
 	  (format
 	   "%s for %s "
-	   (if (string-match "\\([pP]assword\\|[pP]assphrase\\)" message)
+	   (if (string-match
+		(rx (group (any "Pp") (| "assword" "assphrase"))) message)
 	       (capitalize (match-string 1 message))
 	     "Password")
 	   filename))
@@ -1861,7 +1869,7 @@ Their full names are \"org.gtk.vfs.MountTracker.mounted\" and
 		   (cadr (assoc "ssl" (cadr mount-spec)))))
 	     (uri (tramp-gvfs-dbus-byte-array-to-string
 		   (cadr (assoc "uri" (cadr mount-spec))))))
-	(when (string-match "^\\(afp\\|smb\\)" method)
+	(when (string-match (rx bol (group (| "afp" "smb"))) method)
 	  (setq method (match-string 1 method)))
 	(when (and (string-equal "dav" method) (string-equal "true" ssl))
 	  (setq method "davs"))
@@ -1961,7 +1969,7 @@ Their full names are \"org.gtk.vfs.MountTracker.mounted\" and
 		      (or
 		       (cadr (assoc "share" (cadr mount-spec)))
 		       (cadr (assoc "volume" (cadr mount-spec)))))))
-	 (when (string-match "^\\(afp\\|smb\\)" method)
+	 (when (string-match (rx bol (group (| "afp" "smb"))) method)
 	   (setq method (match-string 1 method)))
 	 (when (and (string-equal "dav" method) (string-equal "true" ssl))
 	   (setq method "davs"))
@@ -1993,7 +2001,7 @@ Their full names are \"org.gtk.vfs.MountTracker.mounted\" and
 		(string-equal domain (tramp-file-name-domain vec))
 		(string-equal host (tramp-file-name-host vec))
 		(string-equal port (tramp-file-name-port vec))
-		(string-match-p (concat "^/" (regexp-quote (or share "")))
+		(string-match-p (rx bol "/" (literal (or share "")))
 				(tramp-file-name-unquote-localname vec)))
 	   ;; Set mountpoint and location.
 	   (tramp-set-file-property vec "/" "fuse-mountpoint" fuse-mountpoint)
@@ -2019,7 +2027,7 @@ Their full names are \"org.gtk.vfs.MountTracker.mounted\" and
 (defun tramp-gvfs-mount-spec-entry (key value)
   "Construct a mount-spec entry to be used in a mount_spec.
 It was \"a(say)\", but has changed to \"a{sv})\"."
-  (if (string-match-p "^(aya{sv})" tramp-gvfs-mountlocation-signature)
+  (if (string-match-p (rx bol "(aya{sv})") tramp-gvfs-mountlocation-signature)
       (list :dict-entry key
 	    (list :variant (tramp-gvfs-dbus-string-to-byte-array value)))
     (list :struct key (tramp-gvfs-dbus-string-to-byte-array value))))
@@ -2037,9 +2045,11 @@ It was \"a(say)\", but has changed to \"a{sv})\"."
 	 (port (if media
 		   (tramp-media-device-port media) (tramp-file-name-port vec)))
 	 (localname (tramp-file-name-unquote-localname vec))
-	 (share (when (string-match "^/?\\([^/]+\\)" localname)
+	 (share (when (string-match
+		       (rx bol (? "/") (group (+ (not (any "/"))))) localname)
 		  (match-string 1 localname)))
-	 (ssl (if (string-match-p "^davs\\|^nextcloud" method) "true" "false"))
+	 (ssl (if (string-match-p (rx bol (| "davs" "nextcloud")) method)
+		  "true" "false"))
 	 (mount-spec
           `(:array
             ,@(cond
@@ -2047,7 +2057,7 @@ It was \"a(say)\", but has changed to \"a{sv})\"."
                 (list (tramp-gvfs-mount-spec-entry "type" "smb-share")
                       (tramp-gvfs-mount-spec-entry "server" host)
                       (tramp-gvfs-mount-spec-entry "share" share)))
-               ((string-match-p "^dav\\|^nextcloud" method)
+               ((string-match-p (rx bol (| "davs" "nextcloud")) method)
                 (list (tramp-gvfs-mount-spec-entry "type" "dav")
                       (tramp-gvfs-mount-spec-entry "host" host)
                       (tramp-gvfs-mount-spec-entry "ssl" ssl)))
@@ -2061,7 +2071,7 @@ It was \"a(say)\", but has changed to \"a{sv})\"."
                ((string-equal "nextcloud" method)
                 (list (tramp-gvfs-mount-spec-entry "type" "owncloud")
                       (tramp-gvfs-mount-spec-entry "host" host)))
-               ((string-match-p "^http" method)
+               ((string-match-p (rx bol "http") method)
                 (list (tramp-gvfs-mount-spec-entry "type" "http")
                       (tramp-gvfs-mount-spec-entry
 		       "uri"
@@ -2078,8 +2088,8 @@ It was \"a(say)\", but has changed to \"a{sv})\"."
             ,@(when port
                 (list (tramp-gvfs-mount-spec-entry "port" port)))))
 	 (mount-pref
-          (if (and (string-match-p "^dav" method)
-                   (string-match "^/?[^/]+" localname))
+          (if (and (string-match-p (rx bol "dav") method)
+                   (string-match (rx bol (? "/") (+ (not (any "/")))) localname))
               (match-string 0 localname)
 	    (tramp-gvfs-get-remote-prefix vec))))
 
@@ -2166,7 +2176,7 @@ connection if a previous connection has died for some reason."
 		 (string-equal localname "/"))
 	(tramp-user-error vec "Filename must contain an AFP volume"))
 
-      (when (and (string-match-p "davs?" method)
+      (when (and (string-match-p (rx "dav" (? "s")) method)
 		 (string-equal localname "/"))
 	(tramp-user-error vec "Filename must contain a WebDAV share"))
 
@@ -2216,7 +2226,7 @@ connection if a previous connection has died for some reason."
 
 	;; The call must be asynchronously, because of the "askPassword"
 	;; or "askQuestion" callbacks.
-	(if (string-match-p "(so)$" tramp-gvfs-mountlocation-signature)
+	(if (string-match-p (rx "(so)" eol) tramp-gvfs-mountlocation-signature)
 	    (with-tramp-dbus-call-method vec nil
 	      :session tramp-gvfs-service-daemon tramp-gvfs-path-mounttracker
 	      tramp-gvfs-interface-mounttracker tramp-gvfs-mountlocation
@@ -2446,7 +2456,7 @@ It checks for mounted media devices."
 	   (text (zeroconf-service-txt x))
 	   user)
        (when port
-	 (setq host (format "%s%s%d" host tramp-prefix-port-regexp port)))
+	 (setq host (format "%s%s%d" host tramp-prefix-port-format port)))
        ;; A user is marked in a TXT field like "u=guest".
        (while text
 	 (when (string-match "u=\\(.+\\)$" (car text))
@@ -2462,7 +2472,7 @@ This uses \"avahi-browse\" in case D-Bus is not enabled in Avahi."
 	 (ignore-errors
 	   (split-string
 	    (shell-command-to-string (format "avahi-browse -trkp %s" service))
-	    "[\n\r]+" 'omit "^\\+;.*$"))))
+	    (rx (+ (any "\r\n"))) 'omit (rx bol "+;" (* nonl) eol)))))
     (delete-dups
      (mapcar
       (lambda (x)
@@ -2472,7 +2482,7 @@ This uses \"avahi-browse\" in case D-Bus is not enabled in Avahi."
 	       user)
 	  ;; A user is marked in a TXT field like "u=guest".
 	  (while text
-	    (when (string-match "u=\\(.+\\)$" (car text))
+	    (when (string-match (rx "u=" (group (+ nonl)) eol) (car text))
 	      (setq user (match-string 1 (car text))))
 	    (setq text (cdr text)))
 	  (list user host)))
diff --git a/lisp/net/tramp-integration.el b/lisp/net/tramp-integration.el
index 226113d8800..946f9725022 100644
--- a/lisp/net/tramp-integration.el
+++ b/lisp/net/tramp-integration.el
@@ -85,7 +85,8 @@ special handling of `substitute-in-file-name'."
 
 (defun tramp-rfn-eshadow-update-overlay-regexp ()
   "An overlay covering the shadowed part of the filename."
-  (format "[^%s/~]*\\(/\\|~\\)" tramp-postfix-host-format))
+  (rx-to-string
+   `(: (* (not (any ,tramp-postfix-host-format "/~"))) (or "/" "~"))))
 
 (defun tramp-rfn-eshadow-update-overlay ()
   "Update `rfn-eshadow-overlay' to cover shadowed part of minibuffer input.
@@ -215,9 +216,13 @@ NAME must be equal to `tramp-current-connection'."
   ;; Create a pseudo mode `tramp-info-lookup-mode' for Tramp symbol lookup.
   (info-lookup-maybe-add-help
    :mode 'tramp-info-lookup-mode :topic 'symbol
-   :regexp "[^][()`'‘’,\" \t\n]+"
-   :doc-spec '(("(tramp)Function Index" nil "^ -+ .*: " "\\( \\|$\\)")
-	       ("(tramp)Variable Index" nil "^ -+ .*: " "\\( \\|$\\)")))
+   :regexp (rx (+ (not (any "\t\n \"'(),[]`‘’"))))
+   :doc-spec '(("(tramp)Function Index" nil
+		(rx bol " " (+ "-") " " (* nonl) ": ")
+		(rx (group (| " " eol))))
+	       ("(tramp)Variable Index" nil
+		(rx bol " " (+ "-") " " (* nonl) ": ")
+		(rx (group (| " " eol))))))
 
   (add-hook
    'tramp-integration-unload-hook
diff --git a/lisp/net/tramp-rclone.el b/lisp/net/tramp-rclone.el
index 5bee5641bb1..435faf83294 100644
--- a/lisp/net/tramp-rclone.el
+++ b/lisp/net/tramp-rclone.el
@@ -186,7 +186,7 @@ arguments to pass to the OPERATION."
     (delq nil
 	  (mapcar
 	   (lambda (line)
-	     (when (string-match "^\\(\\S-+\\):$" line)
+	     (when (string-match (rx bol (group (+ (not space))) ":" eol) line)
 	       `(nil ,(match-string 1 line))))
 	   (tramp-process-lines nil tramp-rclone-program "listremotes")))))
 
@@ -300,11 +300,11 @@ file names."
 	(let (total used free)
 	  (goto-char (point-min))
 	  (while (not (eobp))
-	    (when (looking-at "Total: [[:space:]]+\\([[:digit:]]+\\)")
+	    (when (looking-at (rx "Total: " (+ space) (group (+ digit))))
 	      (setq total (string-to-number (match-string 1))))
-	    (when (looking-at "Used: [[:space:]]+\\([[:digit:]]+\\)")
+	    (when (looking-at (rx "Used: " (+ space) (group (+ digit))))
 	      (setq used (string-to-number (match-string 1))))
-	    (when (looking-at "Free: [[:space:]]+\\([[:digit:]]+\\)")
+	    (when (looking-at (rx "Free: " (+ space) (group (+ digit))))
 	      (setq free (string-to-number (match-string 1))))
 	    (forward-line))
 	  (when used
@@ -343,7 +343,7 @@ file names."
 	  (tramp-rclone-maybe-open-connection v)
 	  ;; TODO: This shall be handled by `expand-file-name'.
 	  (setq localname
-		(replace-regexp-in-string "^\\." "" (or localname "")))
+		(replace-regexp-in-string (rx bol ".") "" (or localname "")))
 	  (format "%s%s" (tramp-fuse-mounted-p v) localname)))
     ;; It is a local file name.
     filename))
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index ca08c6f0b3d..2489ac9aec9 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -81,10 +81,10 @@ the default storage location, e.g. \"$HOME/.sh_history\"."
                  (string :tag "Redirect to a file")))
 
 ;;;###tramp-autoload
-(defconst tramp-display-escape-sequence-regexp "\e[[:digit:];[]+m"
+(defconst tramp-display-escape-sequence-regexp (rx "\e" (+ (any ";[" digit)) "m")
   "Terminal control escape sequences for display attributes.")
 
-(defconst tramp-device-escape-sequence-regexp "\e[[:digit:][]+n"
+(defconst tramp-device-escape-sequence-regexp (rx "\e" (+ (any "[" digit)) "n")
   "Terminal control escape sequences for device status.")
 
 ;; ksh on OpenBSD 4.5 requires that $PS1 contains a `#' character for
@@ -411,19 +411,19 @@ The string is used in `tramp-methods'.")
 
  (add-to-list 'tramp-default-method-alist
 	      `(,tramp-local-host-regexp
-		,(format "\\`%s\\'" tramp-root-id-string) "su"))
+		,(rx bos (literal tramp-root-id-string) eos) "su"))
 
  (add-to-list 'tramp-default-user-alist
-	      `(,(concat "\\`" (regexp-opt '("su" "sudo" "doas" "ksu")) "\\'")
+	      `(,(rx bos (regexp (regexp-opt '("su" "sudo" "doas" "ksu"))) eos)
 	        nil ,tramp-root-id-string))
  ;; Do not add "ssh" based methods, otherwise ~/.ssh/config would be ignored.
  ;; Do not add "plink" based methods, they ask interactively for the user.
  (add-to-list 'tramp-default-user-alist
-	      `(,(concat
-		  "\\`"
-		  (regexp-opt
-		   '("rcp" "remcp" "rsh" "telnet" "nc" "krlogin" "fcp"))
-		  "\\'")
+	      `(,(rx bos
+		     (regexp
+		      (regexp-opt
+		       '("rcp" "remcp" "rsh" "telnet" "nc" "krlogin" "fcp")))
+		     eos)
 	        nil ,(user-login-name))))
 
 ;;;###tramp-autoload
@@ -518,8 +518,8 @@ The string is used in `tramp-methods'.")
  (tramp-set-completion-function "fcp" tramp-completion-function-alist-ssh))
 
 (defcustom tramp-sh-extra-args
-  '(("/bash\\'" . "-noediting -norc -noprofile")
-    ("/zsh\\'" . "-f +Z -V"))
+  `((,(rx "/bash" eos) . "-noediting -norc -noprofile")
+    (,(rx "/zsh" eos) . "-f +Z -V"))
   "Alist specifying extra arguments to pass to the remote shell.
 Entries are (REGEXP . ARGS) where REGEXP is a regular expression
 matching the shell file name and ARGS is a string specifying the
@@ -1188,7 +1188,7 @@ component is used as the target of the symlink."
 			     (tramp-shell-quote-argument localname)))
 		  (with-current-buffer (tramp-get-connection-buffer v)
 		    (goto-char (point-min))
-                    (buffer-substring (point-min) (line-end-position))))
+		    (buffer-substring (point-min) (line-end-position))))
 
 		 ;; Use Perl implementation.
 		 ((and (tramp-get-remote-perl v)
@@ -1416,7 +1416,7 @@ component is used as the target of the symlink."
 	       (format "%s -ild %s"
 		       (tramp-get-ls-command v)
 		       (tramp-shell-quote-argument localname)))
-              (setq attr (buffer-substring (point) (line-end-position))))
+	      (setq attr (buffer-substring (point) (line-end-position))))
 	    (tramp-set-file-property
 	     v localname "visited-file-modtime-ild" attr))
 	  (setq last-coding-system-used coding-system-used)
@@ -1460,7 +1460,7 @@ of."
 		       (tramp-get-ls-command v)
 		       (tramp-shell-quote-argument localname)))
 	      (with-current-buffer (tramp-get-buffer v)
-                (setq attr (buffer-substring (point) (line-end-position))))
+		(setq attr (buffer-substring (point) (line-end-position))))
 	      (equal
 	       attr
 	       (tramp-get-file-property
@@ -1572,8 +1572,10 @@ ID-FORMAT valid values are `string' and `integer'."
   (with-parsed-tramp-file-name filename nil
     (with-tramp-file-property v localname "file-selinux-context"
       (let ((context '(nil nil nil nil))
-	    (regexp (concat "\\([[:alnum:]_]+\\):" "\\([[:alnum:]_]+\\):"
-			    "\\([[:alnum:]_]+\\):" "\\([[:alnum:]_]+\\)")))
+	    (regexp (rx (group (+ (any "_" alnum))) ":"
+			(group (+ (any "_" alnum))) ":"
+			(group (+ (any "_" alnum))) ":"
+			(group (+ (any "_" alnum))))))
 	(when (and (tramp-remote-selinux-p v)
 		   (tramp-send-command-and-check
 		    v (format
@@ -1582,7 +1584,7 @@ ID-FORMAT valid values are `string' and `integer'."
 		       (tramp-shell-quote-argument localname))))
 	  (with-current-buffer (tramp-get-connection-buffer v)
 	    (goto-char (point-min))
-            (when (re-search-forward regexp (line-end-position) t)
+	    (when (re-search-forward regexp (line-end-position) t)
 	      (setq context (list (match-string 1) (match-string 2)
 				  (match-string 3) (match-string 4))))))
 	;; Return the context.
@@ -1723,7 +1725,7 @@ ID-FORMAT valid values are `string' and `integer'."
 		 ;; On BSD-derived systems files always inherit the
                  ;; parent directory's group, so skip the group-gid
                  ;; test.
-                 (tramp-check-remote-uname v "BSD\\|DragonFly\\|Darwin")
+                 (tramp-check-remote-uname v (rx (| "BSD" "DragonFly" "Darwin")))
 		 (= (file-attribute-group-id attributes)
 		    (tramp-get-remote-gid v 'integer)))))))))
 
@@ -1809,7 +1811,7 @@ ID-FORMAT valid values are `string' and `integer'."
 
 	     ;; Check result code, found in last line of output.
 	     (forward-line -1)
-	     (if (looking-at-p "^fail$")
+	     (if (looking-at-p (rx bol "fail" eol))
 		 (progn
 		   ;; Grab error message from line before last line
 		   ;; (it was put there by `cd 2>&1').
@@ -1817,12 +1819,12 @@ ID-FORMAT valid values are `string' and `integer'."
 		   (tramp-error
 		    v 'file-error
 		    "tramp-sh-handle-file-name-all-completions: %s"
-                    (buffer-substring (point) (line-end-position))))
+		    (buffer-substring (point) (line-end-position))))
 	       ;; For peace of mind, if buffer doesn't end in `fail'
 	       ;; then it should end in `ok'.  If neither are in the
 	       ;; buffer something went seriously wrong on the remote
 	       ;; side.
-	       (unless (looking-at-p "^ok$")
+	       (unless (looking-at-p (rx bol "ok" eol))
 		 (tramp-error
 		  v 'file-error
 		  (concat "tramp-sh-handle-file-name-all-completions: "
@@ -1830,7 +1832,7 @@ ID-FORMAT valid values are `string' and `integer'."
 		  (tramp-shell-quote-argument localname) (buffer-string))))
 
 	     (while (zerop (forward-line -1))
-               (push (buffer-substring (point) (line-end-position)) result)))
+	       (push (buffer-substring (point) (line-end-position)) result)))
 	   result))))))
 
 ;; cp, mv and ln
@@ -2550,7 +2552,7 @@ The method used must be an out-of-band method."
 	       (with-tramp-progress-reporter
                    v 0 (format "Uncompressing %s" file)
 		 (when (tramp-send-command-and-check
-			v (if (string-match-p "%[io]" (nth 2 suffix))
+			v (if (string-match-p (rx "%" (any "io")) (nth 2 suffix))
                               (replace-regexp-in-string
                                "%i" (tramp-shell-quote-argument localname)
                                (nth 2 suffix))
@@ -2659,7 +2661,9 @@ The method used must be an out-of-band method."
 	(save-restriction
 	  (narrow-to-region beg-marker end-marker)
 	  ;; Check for "--dired" output.
-	  (when (re-search-backward "^//DIRED//\\s-+\\(.+\\)$" nil 'noerror)
+	  (when (re-search-backward
+		 (rx bol "//DIRED//" (+ space) (group (+ nonl)) eol)
+		 nil 'noerror)
 	    (let ((beg (match-beginning 1))
 		  (end (match-end 0)))
 	      ;; Now read the numeric positions of file names.
@@ -2731,7 +2735,7 @@ The method used must be an out-of-band method."
 	  ;; Try to insert the amount of free space.
 	  (goto-char (point-min))
 	  ;; First find the line to put it on.
-	  (when (and (re-search-forward "^\\([[:space:]]*total\\)" nil t)
+	  (when (and (re-search-forward (rx bol (group (* space) "total")) nil t)
 		     ;; Emacs 29.1 or later.
 		     (not (fboundp 'dired--insert-disk-space)))
 	    (when-let ((available (get-free-disk-space ".")))
@@ -2758,7 +2762,7 @@ the result will be a local, non-Tramp, file name."
   ;; by `file-name-absolute-p'.
   (if (and (eq system-type 'windows-nt)
 	   (string-match-p
-	    (concat "^\\([[:alpha:]]:\\|" null-device "$\\)") name))
+	    (rx bol (| (: alpha ":") (: (literal null-device) eol))) name))
       (tramp-run-real-handler #'expand-file-name (list name dir))
     ;; Unless NAME is absolute, concat DIR and NAME.
     (unless (file-name-absolute-p name)
@@ -2774,7 +2778,9 @@ the result will be a local, non-Tramp, file name."
 	;; groks tilde expansion!  The function `tramp-find-shell' is
 	;; supposed to find such a shell on the remote host.  Please
 	;; tell me about it when this doesn't work on your system.
-	(when (string-match "\\`~\\([^/]*\\)\\(.*\\)\\'" localname)
+	(when (string-match
+	       (rx bos "~" (group (* (not (any "/")))) (group (* nonl)) eos)
+	       localname)
 	  (let ((uname (match-string 1 localname))
 		(fname (match-string 2 localname))
 		hname)
@@ -2785,7 +2791,7 @@ the result will be a local, non-Tramp, file name."
 	    ;; appropriate either, because ssh and companions might
 	    ;; use a user name from the config file.
 	    (when (and (zerop (length uname))
-		       (string-match-p "\\`su\\(do\\)?\\'" method))
+		       (string-match-p (rx bos "su" (? "do") eos) method))
 	      (setq uname user))
 	    (when (setq hname (tramp-get-home-directory v uname))
 	      (setq localname (concat hname fname)))))
@@ -2794,7 +2800,7 @@ the result will be a local, non-Tramp, file name."
 	(while (string-match "//" localname)
 	  (setq localname (replace-match "/" t t localname)))
 	;; Do not keep "/..".
-	(when (string-match-p "^/\\.\\.?$" localname)
+	(when (string-match-p (rx bos "/" (** 1 2 ".") eos) localname)
 	  (setq localname "/"))
 	;; Do normal `expand-file-name' (this does "/./" and "/../"),
 	;; unless there are tilde characters in file name.
@@ -2802,9 +2808,9 @@ the result will be a local, non-Tramp, file name."
 	;; would be problems with UNC shares or Cygwin mounts.
 	(let ((default-directory tramp-compat-temporary-file-directory))
 	  (tramp-make-tramp-file-name
-	   v (if (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname)
-		 localname
-	       (tramp-drop-volume-letter
+	   v (tramp-drop-volume-letter
+	      (if (string-prefix-p "~" localname)
+		  localname
 		(tramp-run-real-handler
 		 #'expand-file-name (list localname))))))))))
 
@@ -2884,11 +2890,12 @@ implementation will be used."
 		 ;; command.
 		 (heredoc (and (not (bufferp stderr))
 			       (stringp program)
-			       (string-match-p "sh$" program)
+			       (string-match-p (rx "sh" eol) program)
 			       (= (length args) 2)
 			       (string-equal "-c" (car args))
 			       ;; Don't if there is a quoted string.
-			       (not (string-match-p "'\\|\"" (cadr args)))
+			       (not
+				(string-match-p (rx (any "'\"")) (cadr args)))
 			       ;; Check, that /dev/tty is usable.
 			       (tramp-get-remote-dev-tty v)))
 		 ;; When PROGRAM is nil, we just provide a tty.
@@ -3093,7 +3100,7 @@ implementation will be used."
       (let (signal-hook-function)
 	(condition-case nil
 	    (dolist (sig (cdr signals))
-	      (unless (string-match-p "^[[:alnum:]+-]+$" sig)
+	      (unless (string-match-p (rx bol (+ (any "+-" alnum)) eol) sig)
 		(error nil)))
 	  (error (setq signals '(0)))))
       (dotimes (i 128)
@@ -3124,8 +3131,8 @@ implementation will be used."
 		       (tramp-shell-quote-argument (format "kill -%d $$" i))))
 		     (with-current-buffer (tramp-get-connection-buffer vec)
 		       (goto-char (point-min))
-                       (buffer-substring (line-beginning-position)
-                                         (line-end-position)))))
+		       (buffer-substring (line-beginning-position)
+					 (line-end-position)))))
 	     (if (string-empty-p res)
 		 (format "Signal %d" i)
 	       res)))
@@ -3810,8 +3817,8 @@ Fall back to normal file name handler if no Tramp handler exists."
 
     (catch 'doesnt-work
       ;; https://bugs.launchpad.net/bugs/1742946
-      (when
-          (string-match-p "Monitoring not supported\\|No locations given" string)
+      (when (string-match-p
+	     (rx (| "Monitoring not supported" "No locations given")) string)
         (delete-process proc)
         (throw 'doesnt-work nil))
 
@@ -3829,9 +3836,11 @@ Fall back to normal file name handler if no Tramp handler exists."
             ((getenv "EMACS_EMBA_CI") 'GInotifyFileMonitor)
             ((eq system-type 'cygwin) 'GPollFileMonitor)))
           ;; TODO: What happens, if several monitor names are reported?
-          ((string-match "\
-Supported arguments for GIO_USE_FILE_MONITOR environment variable:
-\\s-*\\([[:alpha:]]+\\) - 20" string)
+          ((string-match
+	    (rx "Supported arguments for "
+		"GIO_USE_FILE_MONITOR environment variable:\n"
+		(* space) (group (+ alpha)) " - 20")
+	    string)
 	   (setq pos (match-end 0))
            (intern
 	    (format "G%sFileMonitor" (capitalize (match-string 1 string)))))
@@ -3842,15 +3851,14 @@ Supported arguments for GIO_USE_FILE_MONITOR environment variable:
       (setq string (tramp-compat-string-replace "\n\n" "\n" string))
 
       (while (string-match
-	      (eval-when-compile
-	        (concat "^[^:]+:"
-		        "[[:space:]]\\([^:]+\\):"
-		        "[[:space:]]" (regexp-opt tramp-gio-events t)
-		        "\\([[:space:]]\\([^:]+\\)\\)?$"))
+	      (rx bol (+ (not (any ":"))) ":" space
+		  (group (+ (not (any ":")))) ":" space
+		  (group (regexp (regexp-opt tramp-gio-events)))
+		  (? space (group (+ (not (any ":"))))) eol)
 	      string)
 
         (let* ((file (match-string 1 string))
-	       (file1 (match-string 4 string))
+	       (file1 (match-string 3 string))
 	       (object
 	        (list
 	         proc
@@ -3870,7 +3878,7 @@ Supported arguments for GIO_USE_FILE_MONITOR environment variable:
 	     `(file-notify ,object file-notify-callback))))))
 
     ;; Save rest of the string.
-    (while (string-match "^\n" string)
+    (while (string-match (rx bol "\n") string)
       (setq string (replace-match "" nil nil string)))
     (when (zerop (length string)) (setq string nil))
     (when string (tramp-message proc 10 "Rest string:\n%s" string))
@@ -3883,9 +3891,8 @@ Supported arguments for GIO_USE_FILE_MONITOR environment variable:
     (dolist (line (split-string string "[\n\r]+" 'omit))
       ;; Check, whether there is a problem.
       (unless (string-match
-	       (concat "^[^[:blank:]]+"
-		       "[[:blank:]]+\\([^[:blank:]]+\\)"
-		       "\\([[:blank:]]+\\([^\n\r]+\\)\\)?")
+	       (rx bol (+ (not blank)) (+ blank) (group (+ (not blank)))
+		   (? (+ blank) (group (+ (not (any "\r\n"))))))
 	       line)
 	(tramp-error proc 'file-notify-error line))
 
@@ -3897,7 +3904,7 @@ Supported arguments for GIO_USE_FILE_MONITOR environment variable:
 		 (intern-soft
 		  (tramp-compat-string-replace "_" "-" (downcase x))))
 	       (split-string (match-string 1 line) "," 'omit))
-	      (or (match-string 3 line)
+	      (or (match-string 2 line)
 		  (file-name-nondirectory (process-get proc 'watch-name))))))
 	;; Usually, we would add an Emacs event now.  Unfortunately,
 	;; `unread-command-events' does not accept several events at
@@ -3921,10 +3928,10 @@ Supported arguments for GIO_USE_FILE_MONITOR environment variable:
 	  (goto-char (point-min))
 	  (forward-line)
 	  (when (looking-at
-		 (concat "\\(?:^/[^[:space:]]*[[:space:]]\\)?"
-			 "[[:space:]]*\\([[:digit:]]+\\)"
-			 "[[:space:]]+\\([[:digit:]]+\\)"
-			 "[[:space:]]+\\([[:digit:]]+\\)"))
+		 (rx (? bol "/" (* (not space)) space) (* space)
+		     (group (+ digit)) (+ space)
+		     (group (+ digit)) (+ space)
+		     (group (+ digit))))
 	    (mapcar
 	     (lambda (d)
 	       (* d (tramp-get-connection-property v "df-blocksize" 0)))
@@ -3946,49 +3953,51 @@ by \"2>/dev/null\", and \"%t\" is replaced by a temporary file
 name.  If VEC is nil, the respective local commands are used.  If
 there is a format specifier which cannot be expanded, this
 function returns nil."
-  (if (not (string-match-p "\\(^\\|[^%]\\)%[ahlnoprst]" script))
+  (if (not (string-match-p
+	    (rx (| bol (not (any "%"))) "%" (any "ahlnoprst")) script))
       script
     (catch 'wont-work
-      (let ((awk (when (string-match-p "\\(^\\|[^%]\\)%a" script)
+      (let ((awk (when (string-match-p (rx (| bol (not (any "%"))) "%a") script)
 		   (or
 		    (if vec (tramp-get-remote-awk vec) (executable-find "awk"))
 		    (throw 'wont-work nil))))
-	    (hdmp (when (string-match-p "\\(^\\|[^%]\\)%h" script)
+	    (hdmp (when (string-match-p (rx (| bol (not (any "%"))) "%h") script)
 		    (or
 		     (if vec (tramp-get-remote-hexdump vec)
 		       (executable-find "hexdump"))
 		     (throw 'wont-work nil))))
-	    (dev (when (string-match-p "\\(^\\|[^%]\\)%n" script)
+	    (dev (when (string-match-p (rx (| bol (not (any "%"))) "%n") script)
 		   (or
 		    (if vec (concat "2>" (tramp-get-remote-null-device vec))
 		      (if (eq system-type 'windows-nt) ""
 			(concat "2>" null-device)))
 		    (throw 'wont-work nil))))
-	    (ls (when (string-match-p "\\(^\\|[^%]\\)%l" script)
+	    (ls (when (string-match-p (rx (| bol (not (any "%"))) "%l") script)
 		  (format "%s %s"
 			  (or (tramp-get-ls-command vec)
 			      (throw 'wont-work nil))
 			  (tramp-sh--quoting-style-options vec))))
-	    (od (when (string-match-p "\\(^\\|[^%]\\)%o" script)
+	    (od (when (string-match-p (rx (| bol (not (any "%"))) "%o") script)
 		  (or (if vec (tramp-get-remote-od vec) (executable-find "od"))
 		      (throw 'wont-work nil))))
-	    (perl (when (string-match-p "\\(^\\|[^%]\\)%p" script)
+	    (perl (when (string-match-p (rx (| bol (not (any "%"))) "%p") script)
 		    (or
 		     (if vec
 			 (tramp-get-remote-perl vec) (executable-find "perl"))
 		     (throw 'wont-work nil))))
-	    (readlink (when (string-match-p "\\(^\\|[^%]\\)%r" script)
-		    (or
-		     (if vec
+	    (readlink (when (string-match-p
+			     (rx (| bol (not (any "%"))) "%r") script)
+			(or
+			 (if vec
 			 (tramp-get-remote-readlink vec)
 		       (executable-find "readlink"))
 		     (throw 'wont-work nil))))
-	    (stat (when (string-match-p "\\(^\\|[^%]\\)%s" script)
+	    (stat (when (string-match-p (rx (| bol (not (any "%"))) "%s") script)
 		    (or
 		     (if vec
 			 (tramp-get-remote-stat vec) (executable-find "stat"))
 		     (throw 'wont-work nil))))
-	    (tmp (when (string-match-p "\\(^\\|[^%]\\)%t" script)
+	    (tmp (when (string-match-p (rx (| bol (not (any "%"))) "%t") script)
 		   (or
 		    (if vec
 			(tramp-file-local-name (tramp-make-tramp-temp-name vec))
@@ -4061,7 +4070,7 @@ This function expects to be in the right *tramp* buffer."
       (unless (or ignore-path (tramp-check-remote-uname vec tramp-sunos-unames))
 	(tramp-send-command vec (format "which \\%s | wc -w" progname))
 	(goto-char (point-min))
-	(if (looking-at-p "^\\s-*1$")
+	(if (looking-at-p (rx bol (* space) "1" eol))
 	    (setq result (concat "\\" progname))))
       (unless result
 	(when ignore-tilde
@@ -4088,8 +4097,8 @@ This function expects to be in the right *tramp* buffer."
 	(when (search-backward "tramp_executable " nil t)
 	  (skip-chars-forward "^ ")
 	  (skip-chars-forward " ")
-          (setq result (buffer-substring (point) (line-end-position)))))
-      result)))
+	  (setq result (buffer-substring (point) (line-end-position)))))
+    result)))
 
 ;; On hydra.nixos.org, the $PATH environment variable is too long to
 ;; send it.  This is likely not due to PATH_MAX, but PIPE_BUF.  We
@@ -4101,7 +4110,8 @@ whether it exists and if so, it is added to the environment
 variable PATH."
   (let ((command
 	 (format
-	  "PATH=%s && export PATH" (string-join (tramp-get-remote-path vec) ":")))
+	  "PATH=%s && export PATH"
+	  (string-join (tramp-get-remote-path vec) ":")))
 	(pipe-buf
 	 (with-tramp-connection-property vec "pipe-buf"
 	   (tramp-send-command-and-read
@@ -4227,9 +4237,10 @@ file exists and nonzero exit status otherwise."
     ;; first.
     (tramp-send-command
      vec (format
-	  (concat
-	   "exec env TERM='%s' INSIDE_EMACS='%s' "
-	   "ENV=%s %s PROMPT_COMMAND='' PS1=%s PS2='' PS3='' %s %s -i")
+	  (eval-when-compile
+	    (concat
+	     "exec env TERM='%s' INSIDE_EMACS='%s' "
+	     "ENV=%s %s PROMPT_COMMAND='' PS1=%s PS2='' PS3='' %s %s -i"))
           tramp-terminal-type (tramp-inside-emacs)
           (or (getenv-internal "ENV" tramp-remote-process-environment) "")
 	  (if (stringp tramp-histfile-override)
@@ -4244,16 +4255,21 @@ file exists and nonzero exit status otherwise."
 
     ;; Sanity check.
     (tramp-barf-if-no-shell-prompt
-     (tramp-get-connection-process vec) 10
+     (tramp-get-connection-process vec) 60
      "Couldn't find remote shell prompt for %s" shell)
     (unless
 	(tramp-check-for-regexp
-	 (tramp-get-connection-process vec) (regexp-quote tramp-end-of-output))
+	 (tramp-get-connection-process vec) (rx (literal tramp-end-of-output)))
+      (tramp-wait-for-output (tramp-get-connection-process vec))
       (tramp-message vec 5 "Setting shell prompt")
       (tramp-send-command
        vec (format "PS1=%s PS2='' PS3='' PROMPT_COMMAND=''"
 		   (tramp-shell-quote-argument tramp-end-of-output))
-       t))
+       t t)
+      (tramp-barf-if-no-shell-prompt
+       (tramp-get-connection-process vec) 60
+       "Couldn't find remote shell prompt for %s" shell))
+    (tramp-wait-for-output (tramp-get-connection-process vec))
 
     ;; Check proper HISTFILE setting.  We give up when not working.
     (when (and (stringp tramp-histfile-override)
@@ -4284,7 +4300,8 @@ file exists and nonzero exit status otherwise."
 		(tramp-send-command
 		 vec (format "echo ~%s" tramp-root-id-string) t)
 		(if (or (string-match-p
-			 (format "^~%s$" tramp-root-id-string) (buffer-string))
+			 (rx bol "~" (literal tramp-root-id-string) eol)
+			 (buffer-string))
 			;; The default shell (ksh93) of OpenSolaris
 			;; and Solaris is buggy.  We've got reports
 			;; for "SunOS 5.10" and "SunOS 5.11" so far.
@@ -4299,9 +4316,10 @@ file exists and nonzero exit status otherwise."
 			    default-shell
 			  (tramp-message
 			   vec 2
-			   (concat
-			    "Couldn't find a remote shell which groks tilde "
-			    "expansion, using `%s'")
+			   (eval-when-compile
+			     (concat
+			      "Couldn't find a remote shell which groks tilde "
+			      "expansion, using `%s'"))
 			   default-shell)))
 
 		  default-shell)))
@@ -4322,8 +4340,9 @@ seconds.  If not, it produces an error message with the given ERROR-ARGS."
     (condition-case nil
 	(tramp-wait-for-regexp
 	 proc timeout
-	 (format
-	  "\\(%s\\|%s\\)\\'" shell-prompt-pattern tramp-shell-prompt-pattern))
+	 (rx (| (regexp shell-prompt-pattern)
+		(regexp tramp-shell-prompt-pattern))
+	     eos))
       (error
        (delete-process proc)
        (apply #'tramp-error-with-buffer
@@ -4392,7 +4411,8 @@ process to set up.  VEC specifies the connection."
 			 (string-prefix-p "Darwin" uname)
 			 (cons 'utf-8-hfs 'utf-8-hfs))
 		    (and (memq 'utf-8 (coding-system-list))
-			 (string-match-p "utf-?8" (tramp-get-remote-locale vec))
+			 (string-match-p
+			  (rx "utf" (? "-") "8") (tramp-get-remote-locale vec))
 			 (cons 'utf-8 'utf-8))
 		    (process-coding-system proc)
 		    (cons 'undecided 'undecided)))
@@ -4424,7 +4444,7 @@ process to set up.  VEC specifies the connection."
        (t
 	(tramp-message
 	 vec 5 "Checking remote host type for `send-process-string' bug")
-	(if (string-match-p "FreeBSD\\|DragonFly" uname) 500 0))))
+	(if (string-match-p (rx (| "FreeBSD" "DragonFly")) uname) 500 0))))
 
     ;; Set remote PATH variable.
     (tramp-set-remote-path vec)
@@ -4456,7 +4476,7 @@ process to set up.  VEC specifies the connection."
       (tramp-send-command vec "set +H" t))
 
     ;; Disable tab expansion.
-    (if (string-match-p "BSD\\|DragonFly\\|Darwin" uname)
+    (if (string-match-p (rx (| "BSD" "DragonFly" "Darwin")) uname)
 	(tramp-send-command vec "stty tabs" t)
       (tramp-send-command vec "stty tab0" t))
 
@@ -4682,7 +4702,7 @@ Goes through the list `tramp-local-coding-commands' and
 
 		  (with-current-buffer (tramp-get-connection-buffer vec)
 		    (goto-char (point-min))
-		    (unless (looking-at-p (regexp-quote magic))
+		    (unless (looking-at-p (rx (literal magic)))
 		      (throw 'wont-work-remote nil)))
 
 		  ;; `rem-enc' and `rem-dec' could be a string meanwhile.
@@ -4768,7 +4788,7 @@ Goes through the list `tramp-inline-compress-commands'."
 	              nil t))
               (throw 'next nil))
 	    (goto-char (point-min))
-	    (unless (looking-at-p (regexp-quote magic))
+	    (unless (looking-at-p (rx (literal magic)))
 	      (throw 'next nil)))
           (tramp-message
 	   vec 5
@@ -4779,7 +4799,7 @@ Goes through the list `tramp-inline-compress-commands'."
 	    (throw 'next nil))
 	  (with-current-buffer (tramp-get-buffer vec)
 	    (goto-char (point-min))
-	    (unless (looking-at-p (regexp-quote magic))
+	    (unless (looking-at-p (rx (literal magic)))
 	      (throw 'next nil)))
 	  (setq found t)))
 
@@ -4868,7 +4888,7 @@ Goes through the list `tramp-inline-compress-commands'."
 		(goto-char (point-min))
 		(unless
                     (search-forward-regexp
-                     "\\(illegal\\|unknown\\) option -- T" nil t)
+                     (rx (| "illegal" "unknown") " option -- T") nil t)
 		  (setq tramp-scp-strict-file-name-checking "-T")))))))
       tramp-scp-strict-file-name-checking)))
 
@@ -4895,7 +4915,7 @@ Goes through the list `tramp-inline-compress-commands'."
 		(goto-char (point-min))
 		(unless
                     (search-forward-regexp
-                     "\\(illegal\\|unknown\\) option -- O" nil t)
+                     (rx (| "illegal" "unknown") " option -- O") nil t)
 		  (setq tramp-scp-force-scp-protocol "-O")))))))
       tramp-scp-force-scp-protocol)))
 
@@ -4918,7 +4938,7 @@ Goes through the list `tramp-inline-compress-commands'."
 	     (tramp-call-process vec1 "scp" nil t nil "-R")
 	     (goto-char (point-min))
 	     (not (search-forward-regexp
-		   "\\(illegal\\|unknown\\) option -- R" nil 'noerror)))))
+		   (rx (| "illegal" "unknown") " option -- R") nil 'noerror)))))
 
        ;; Check, that RemoteCommand is not used.
        (with-tramp-connection-property
@@ -4959,7 +4979,10 @@ Goes through the list `tramp-inline-compress-commands'."
 		      (line-beginning-position) (line-end-position))
 		     string
 		     (and
-		      (string-match "^[^# ]+ \\S-+ \\(\\S-+\\)$" string)
+		      (string-match
+		       (rx bol (+ (not (any " #"))) " " (+ (not space)) " "
+			   (group (+ (not space))) eol)
+		       string)
 		      (match-string 1 string))
 		     found
 		     (and string
@@ -5264,20 +5287,22 @@ function waits for output unless NOOUTPUT is set."
 	   ;; Busyboxes built with the EDITING_ASK_TERMINAL config
 	   ;; option send also escape sequences, which must be
 	   ;; ignored.
-	   (regexp (format "[^#$\n]*%s\\(%s\\)?\r?$"
-			   (regexp-quote tramp-end-of-output)
-			   tramp-device-escape-sequence-regexp))
+	   (regexp (rx (* (not (any "#$\n")))
+		       (literal tramp-end-of-output)
+		       (? (regexp tramp-device-escape-sequence-regexp))
+		       (? "\r") eol))
 	   ;; Sometimes, the commands do not return a newline but a
 	   ;; null byte before the shell prompt, for example "git
 	   ;; ls-files -c -z ...".
-	   (regexp1 (format "\\(^\\|\000\\)%s" regexp))
+	   (regexp1 (rx (| bol "\000") (regexp regexp)))
 	   (found (tramp-wait-for-regexp proc timeout regexp1)))
       (if found
 	  (let ((inhibit-read-only t))
 	    ;; A simple-minded busybox has sent " ^H" sequences.
 	    ;; Delete them.
 	    (goto-char (point-min))
-            (when (re-search-forward "^\\(.\b\\)+$" (line-end-position) t)
+	    (when (re-search-forward
+		   (rx bol (+ nonl "\b") eol) (line-end-position) t)
 	      (forward-line 1)
 	      (delete-region (point-min) (point)))
 	    ;; Delete the prompt.
@@ -5308,7 +5333,9 @@ Optional argument EXIT-STATUS, if non-nil, triggers the return of
 the exit status."
   (let (cmd data)
     (if (and (stringp command)
-	     (string-match (format ".*<<'%s'.*" tramp-end-of-heredoc) command))
+	     (string-match
+	      (rx (* nonl) "<<'" (literal tramp-end-of-heredoc) "'" (* nonl))
+	      command))
 	(setq cmd (match-string 0 command)
 	      data (substring command (match-end 0)))
       (setq cmd command))
@@ -5324,7 +5351,7 @@ the exit status."
 	     (if subshell " )" "")
 	     data)))
   (with-current-buffer (tramp-get-connection-buffer vec)
-    (unless (tramp-search-regexp "tramp_exit_status [[:digit:]]+")
+    (unless (tramp-search-regexp (rx "tramp_exit_status " (+ digit)))
       (tramp-error
        vec 'file-error "Couldn't find exit status of `%s'" command))
     (skip-chars-forward "^ ")
@@ -5369,7 +5396,7 @@ raises an error."
 		     (unless noerror signal-hook-function)))
 		(read (current-buffer)))
 	    ;; Error handling.
-            (when (re-search-forward "\\S-" (line-end-position) t)
+	    (when (re-search-forward (rx (not space)) (line-end-position) t)
 	      (error nil)))
 	(error (unless noerror
 		 (tramp-error
@@ -5399,7 +5426,7 @@ raises an error."
     ;; This does not work for MS Windows scp, if there are characters
     ;; to be quoted.  OpenSSH 8 supports disabling of strict file name
     ;; checking in scp, we use it when available.
-    (unless (string-match-p "ftp$" method)
+    (unless (string-match-p (rx "ftp" eos) method)
       (setq localname (tramp-unquote-shell-quote-argument localname)))
     (cond
      ((tramp-get-method-parameter vec 'tramp-remote-copy-program)
@@ -5477,7 +5504,7 @@ Nonexistent directories are removed from spec."
 		    (tramp-get-method-parameter vec 'tramp-remote-shell-args)
 		    " ")
 		   (tramp-shell-quote-argument tramp-end-of-heredoc))
-		  'noerror (regexp-quote tramp-end-of-heredoc))
+		  'noerror (rx (literal tramp-end-of-heredoc)))
 		 (progn
 		   (tramp-message
 		    vec 2 "Could not retrieve `tramp-own-remote-path'")
@@ -5526,8 +5553,9 @@ Nonexistent directories are removed from spec."
       (with-current-buffer (tramp-get-connection-buffer vec)
 	(while candidates
 	  (goto-char (point-min))
-	  (if (string-match-p (format "^%s\r?$" (regexp-quote (car candidates)))
-			      (buffer-string))
+	  (if (string-match-p
+	       (rx bol (literal (car candidates))"%s" (? "\r") eol)
+	       (buffer-string))
 	      (setq locale (car candidates)
 		    candidates nil)
 	    (setq candidates (cdr candidates)))))
@@ -5557,7 +5585,7 @@ Nonexistent directories are removed from spec."
 				"%s --color=never -al %s"
 				result (tramp-get-remote-null-device vec)))
 			  (not (string-match-p
-				(regexp-quote "\e")
+				"\e"
 				(tramp-get-buffer-string
 				 (tramp-get-buffer vec)))))
 		 (setq result (concat result " --color=never")))
@@ -5605,7 +5633,7 @@ Nonexistent directories are removed from spec."
 	vec (format "( %s / -nt / )" (tramp-get-test-command vec)))
        (with-current-buffer (tramp-get-buffer vec)
 	 (goto-char (point-min))
-	 (when (looking-at-p (regexp-quote tramp-end-of-output))
+	 (when (looking-at-p (rx (literal tramp-end-of-output)))
 	   (format "%s %%s -nt %%s" (tramp-get-test-command vec)))))
      (progn
        (tramp-send-command
@@ -5670,7 +5698,9 @@ Nonexistent directories are removed from spec."
 		tmp (tramp-send-command-and-read
 		     vec (format "%s -c '(\"%%N\" %%s)' /" result) 'noerror))
 	  (unless (and (listp tmp) (stringp (car tmp))
-		       (string-match-p "^[\"`‘„”«「]/[\"'’“”»」]$" (car tmp))
+		       (string-match-p
+			(rx bol (any "\"`'‘„”«「") "/" (any "\"'’“”»」") eol)
+			(car tmp))
 		       (integerp (cadr tmp)))
 	    (setq result nil)))
 	result))))
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index ba0a1d3598f..9e63d532626 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -53,7 +53,7 @@
 ;;;###tramp-autoload
 (tramp--with-startup
  (add-to-list 'tramp-default-user-alist
-	      `(,(concat "\\`" tramp-smb-method "\\'") nil nil))
+	      `(,(rx bos (literal tramp-smb-method) eos) nil nil))
 
  ;; Add completion function for SMB method.
  (tramp-set-completion-function
@@ -92,10 +92,15 @@ this variable \"client min protocol=NT1\"."
   "Version string of the SMB client.")
 
 (defconst tramp-smb-server-version
-  "Domain=\\[[^]]*\\] OS=\\[[^]]*\\] Server=\\[[^]]*\\]"
+  (rx "Domain=[" (* (not (any "]"))) "] "
+      "OS=[" (* (not (any "]"))) "] "
+      "Server=[" (* (not (any "]"))) "]")
   "Regexp of SMB server identification.")
 
-(defconst tramp-smb-prompt "^\\(smb:\\|PS\\) .+> \\|^\\s-+Server\\s-+Comment$"
+(defconst tramp-smb-prompt
+  (rx bol (| (: (| "smb:" "PS") " " (+ nonl) "> ")
+	     (: (+ space) "Server"
+		(+ space) "Comment" eol)))
   "Regexp used as prompt in smbclient or powershell.")
 
 (defconst tramp-smb-wrong-passwd-regexp
@@ -105,66 +110,63 @@ this variable \"client min protocol=NT1\"."
   "Regexp for login error strings of SMB servers.")
 
 (defconst tramp-smb-errors
-  (mapconcat
-   #'identity
-   `(;; Connection error / timeout / unknown command.
-     "Connection\\( to \\S-+\\)? failed"
-     "Read from server failed, maybe it closed the connection"
-     "Call timed out: server did not respond"
-     "\\S-+: command not found"
-     "Server doesn't support UNIX CIFS calls"
-     ,(regexp-opt
-       '(;; Samba.
-	 "ERRDOS"
-	 "ERRHRD"
-	 "ERRSRV"
-	 "ERRbadfile"
-	 "ERRbadpw"
-	 "ERRfilexists"
-	 "ERRnoaccess"
-	 "ERRnomem"
-	 "ERRnosuchshare"
-	 ;; See /usr/include/samba-4.0/core/ntstatus.h.
-	 ;; Windows 4.0 (Windows NT), Windows 5.0 (Windows 2000),
-	 ;; Windows 5.1 (Windows XP), Windows 5.2 (Windows Server 2003),
-	 ;; Windows 6.0 (Windows Vista), Windows 6.1 (Windows 7),
-	 ;; Windows 6.3 (Windows Server 2012, Windows 10).
-	 "NT_STATUS_ACCESS_DENIED"
-	 "NT_STATUS_ACCOUNT_LOCKED_OUT"
-	 "NT_STATUS_BAD_NETWORK_NAME"
-	 "NT_STATUS_CANNOT_DELETE"
-	 "NT_STATUS_CONNECTION_DISCONNECTED"
-	 "NT_STATUS_CONNECTION_REFUSED"
-	 "NT_STATUS_CONNECTION_RESET"
-	 "NT_STATUS_DIRECTORY_NOT_EMPTY"
-	 "NT_STATUS_DUPLICATE_NAME"
-	 "NT_STATUS_FILE_IS_A_DIRECTORY"
-	 "NT_STATUS_HOST_UNREACHABLE"
-	 "NT_STATUS_IMAGE_ALREADY_LOADED"
-	 "NT_STATUS_INVALID_LEVEL"
-	 "NT_STATUS_INVALID_PARAMETER"
-	 "NT_STATUS_INVALID_PARAMETER_MIX"
-	 "NT_STATUS_IO_TIMEOUT"
-	 "NT_STATUS_LOGON_FAILURE"
-	 "NT_STATUS_NETWORK_ACCESS_DENIED"
-	 "NT_STATUS_NOT_IMPLEMENTED"
-	 "NT_STATUS_NO_LOGON_SERVERS"
-	 "NT_STATUS_NO_SUCH_FILE"
-	 "NT_STATUS_NO_SUCH_USER"
-	 "NT_STATUS_NOT_A_DIRECTORY"
-	 "NT_STATUS_NOT_SUPPORTED"
-	 "NT_STATUS_OBJECT_NAME_COLLISION"
-	 "NT_STATUS_OBJECT_NAME_INVALID"
-	 "NT_STATUS_OBJECT_NAME_NOT_FOUND"
-	 "NT_STATUS_OBJECT_PATH_SYNTAX_BAD"
-	 "NT_STATUS_PASSWORD_MUST_CHANGE"
-	 "NT_STATUS_RESOURCE_NAME_NOT_FOUND"
-	 "NT_STATUS_REVISION_MISMATCH"
-	 "NT_STATUS_SHARING_VIOLATION"
-	 "NT_STATUS_TRUSTED_RELATIONSHIP_FAILURE"
-	 "NT_STATUS_UNSUCCESSFUL"
-	 "NT_STATUS_WRONG_PASSWORD")))
-   "\\|")
+  (rx (| ;; Connection error / timeout / unknown command.
+       (: "Connection" (? " to " (+ (not space))) " failed")
+       "Read from server failed, maybe it closed the connection"
+       "Call timed out: server did not respond"
+       (: (+ (not space)) ": command not found")
+       "Server doesn't support UNIX CIFS calls"
+       (regexp (regexp-opt
+		'(;; Samba.
+		  "ERRDOS"
+		  "ERRHRD"
+		  "ERRSRV"
+		  "ERRbadfile"
+		  "ERRbadpw"
+		  "ERRfilexists"
+		  "ERRnoaccess"
+		  "ERRnomem"
+		  "ERRnosuchshare"
+		  ;; See /usr/include/samba-4.0/core/ntstatus.h.
+		  ;; Windows 4.0 (Windows NT), Windows 5.0 (Windows 2000),
+		  ;; Windows 5.1 (Windows XP), Windows 5.2 (Windows Server 2003),
+		  ;; Windows 6.0 (Windows Vista), Windows 6.1 (Windows 7),
+		  ;; Windows 6.3 (Windows Server 2012, Windows 10).
+		  "NT_STATUS_ACCESS_DENIED"
+		  "NT_STATUS_ACCOUNT_LOCKED_OUT"
+		  "NT_STATUS_BAD_NETWORK_NAME"
+		  "NT_STATUS_CANNOT_DELETE"
+		  "NT_STATUS_CONNECTION_DISCONNECTED"
+		  "NT_STATUS_CONNECTION_REFUSED"
+		  "NT_STATUS_CONNECTION_RESET"
+		  "NT_STATUS_DIRECTORY_NOT_EMPTY"
+		  "NT_STATUS_DUPLICATE_NAME"
+		  "NT_STATUS_FILE_IS_A_DIRECTORY"
+		  "NT_STATUS_HOST_UNREACHABLE"
+		  "NT_STATUS_IMAGE_ALREADY_LOADED"
+		  "NT_STATUS_INVALID_LEVEL"
+		  "NT_STATUS_INVALID_PARAMETER"
+		  "NT_STATUS_INVALID_PARAMETER_MIX"
+		  "NT_STATUS_IO_TIMEOUT"
+		  "NT_STATUS_LOGON_FAILURE"
+		  "NT_STATUS_NETWORK_ACCESS_DENIED"
+		  "NT_STATUS_NOT_IMPLEMENTED"
+		  "NT_STATUS_NO_LOGON_SERVERS"
+		  "NT_STATUS_NO_SUCH_FILE"
+		  "NT_STATUS_NO_SUCH_USER"
+		  "NT_STATUS_NOT_A_DIRECTORY"
+		  "NT_STATUS_NOT_SUPPORTED"
+		  "NT_STATUS_OBJECT_NAME_COLLISION"
+		  "NT_STATUS_OBJECT_NAME_INVALID"
+		  "NT_STATUS_OBJECT_NAME_NOT_FOUND"
+		  "NT_STATUS_OBJECT_PATH_SYNTAX_BAD"
+		  "NT_STATUS_PASSWORD_MUST_CHANGE"
+		  "NT_STATUS_RESOURCE_NAME_NOT_FOUND"
+		  "NT_STATUS_REVISION_MISMATCH"
+		  "NT_STATUS_SHARING_VIOLATION"
+		  "NT_STATUS_TRUSTED_RELATIONSHIP_FAILURE"
+		  "NT_STATUS_UNSUCCESSFUL"
+		  "NT_STATUS_WRONG_PASSWORD")))))
   "Regexp for possible error strings of SMB servers.
 Used instead of analyzing error codes of commands.")
 
@@ -727,7 +729,9 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
     ;; Dissect NAME.
     (with-parsed-tramp-file-name name nil
       ;; Tilde expansion if necessary.
-      (when (string-match "\\`~\\([^/]*\\)\\(.*\\)\\'" localname)
+      (when (string-match
+	     (rx bos "~" (group (* (not (any "/")))) (group (* nonl)) eos)
+	     localname)
 	(let ((uname (match-string 1 localname))
 	      (fname (match-string 2 localname))
 	      hname)
@@ -737,17 +741,17 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 	    (setq localname (concat hname fname)))))
       ;; Tilde expansion is not possible.
       (when (and (not tramp-tolerate-tilde)
-		 (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname))
+		 (string-prefix-p "~" localname))
 	(tramp-error v 'file-error "Cannot expand tilde in file `%s'" name))
       (unless (tramp-run-real-handler #'file-name-absolute-p (list localname))
 	(setq localname (concat "/" localname)))
      ;; Do not keep "/..".
-      (when (string-match-p "^/\\.\\.?$" localname)
+      (when (string-match-p (rx bos "/" (** 1 2 ".") eos) localname)
 	(setq localname "/"))
       ;; Do normal `expand-file-name' (this does "/./" and "/../"),
       ;; unless there are tilde characters in file name.
       (tramp-make-tramp-file-name
-       v (if (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname)
+       v (if (string-prefix-p "~" localname)
 	     localname
 	   (tramp-run-real-handler #'expand-file-name (list localname)))))))
 
@@ -765,10 +769,10 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
       (widen)
       (tramp-message vec 10 "\n%s" (buffer-string))
       (goto-char (point-min))
-      (while (and (not (eobp)) (not (looking-at-p "^REVISION:")))
+      (while (and (not (eobp)) (not (looking-at-p (rx bol "REVISION:"))))
 	(forward-line)
 	(delete-region (point-min) (point)))
-      (while (and (not (eobp)) (looking-at-p "^.+:.+"))
+      (while (and (not (eobp)) (looking-at-p (rx bol (+ nonl) ":" (+ nonl))))
  	(forward-line))
       (delete-region (point) (point-max))
       (throw 'tramp-action 'ok))))
@@ -882,29 +886,30 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 	  (while (not (eobp))
 	    (cond
 	     ((looking-at
-	       (concat
-		"Size:\\s-+\\([[:digit:]]+\\)\\s-+"
-		"Blocks:\\s-+[[:digit:]]+\\s-+\\(\\w+\\)"))
+	       (rx "Size:" (+ space) (group (+ digit)) (+ space)
+		   "Blocks:" (+ space) (+ digit) (+ space) (group (+ wordchar))))
 	      (setq size (string-to-number (match-string 1))
 		    id (if (string-equal "directory" (match-string 2)) t
 			 (if (string-equal "symbolic" (match-string 2)) ""))))
 	     ((looking-at
-	       "Inode:\\s-+\\([[:digit:]]+\\)\\s-+Links:\\s-+\\([[:digit:]]+\\)")
+	       (rx "Inode:" (+ space) (group (+ digit)) (+ space)
+		   "Links:" (+ space) (group (+ digit))))
 	      (setq inode (string-to-number (match-string 1))
 		    link (string-to-number (match-string 2))))
 	     ((looking-at
-	       (concat
-		"Access:\\s-+([[:digit:]]+/\\(\\S-+\\))\\s-+"
-		"Uid:\\s-+\\([[:digit:]]+\\)\\s-+"
-		"Gid:\\s-+\\([[:digit:]]+\\)"))
+	       (rx "Access:" (+ space)
+		   "(" (+ digit) "/" (group (+ (not space))) ")" (+ space)
+		   "Uid:" (+ space) (group (+ digit)) (+ whitespace)
+		   "Gid:" (+ space) (group (+ digit))))
 	      (setq mode (match-string 1)
 		    uid (match-string 2)
 		    gid (match-string 3)))
 	     ((looking-at
-	       (concat
-		"Access:\\s-+"
-		"\\([[:digit:]]+\\)-\\([[:digit:]]+\\)-\\([[:digit:]]+\\)\\s-+"
-		"\\([[:digit:]]+\\):\\([[:digit:]]+\\):\\([[:digit:]]+\\)"))
+	       (rx "Access:" (+ space)
+		   (group (+ digit)) "-" (group (+ digit)) "-"
+		   (group (+ digit)) (+ space)
+		   (group (+ digit)) ":" (group (+ digit)) ":"
+		   (group (+ digit))))
 	      (setq atime
 		    (encode-time
 		     (string-to-number (match-string 6)) ;; sec
@@ -914,10 +919,11 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 		     (string-to-number (match-string 2)) ;; month
 		     (string-to-number (match-string 1))))) ;; year
 	     ((looking-at
-	       (concat
-		"Modify:\\s-+"
-		"\\([[:digit:]]+\\)-\\([[:digit:]]+\\)-\\([[:digit:]]+\\)\\s-+"
-		"\\([[:digit:]]+\\):\\([[:digit:]]+\\):\\([[:digit:]]+\\)"))
+	       (rx "Modify:" (+ space)
+		   (group (+ digit)) "-" (group (+ digit)) "-"
+		   (group (+ digit)) (+ space)
+		   (group (+ digit)) ":" (group (+ digit)) ":"
+		   (group (+ digit))))
 	      (setq mtime
 		    (encode-time
 		     (string-to-number (match-string 6)) ;; sec
@@ -927,10 +933,11 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 		     (string-to-number (match-string 2)) ;; month
 		     (string-to-number (match-string 1))))) ;; year
 	     ((looking-at
-	       (concat
-		"Change:\\s-+"
-		"\\([[:digit:]]+\\)-\\([[:digit:]]+\\)-\\([[:digit:]]+\\)\\s-+"
-		"\\([[:digit:]]+\\):\\([[:digit:]]+\\):\\([[:digit:]]+\\)"))
+	       (rx "Change:" (+ space)
+		   (group (+ digit)) "-" (group (+ digit)) "-"
+		   (group (+ digit)) (+ space)
+		   (group (+ digit)) ":" (group (+ digit)) ":"
+		   (group (+ digit))))
 	      (setq ctime
 		    (encode-time
 		     (string-to-number (match-string 6)) ;; sec
@@ -948,7 +955,7 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 		      (format
 		       "readlink %s" (tramp-smb-shell-quote-localname vec))))
 	    (goto-char (point-min))
-	    (and (looking-at ".+ -> \\(.+\\)")
+	    (and (looking-at (rx (+ nonl) " -> " (group (+ nonl))))
 		 (setq id (match-string 1))))
 
 	  ;; Return the result.
@@ -1003,14 +1010,14 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 	    (goto-char (point-min))
 	    (forward-line)
 	    (when (looking-at
-		   (concat "[[:space:]]*\\([[:digit:]]+\\)"
-			   " blocks of size \\([[:digit:]]+\\)"
-			   "\\. \\([[:digit:]]+\\) blocks available"))
+		   (rx (* space) (group (+ digit))
+		       " blocks of size " (group (+ digit))
+		       ". " (group (+ digit)) " blocks available"))
 	      (setq blocksize (string-to-number (match-string 2))
 		    total (* blocksize (string-to-number (match-string 1)))
 		    avail (* blocksize (string-to-number (match-string 3)))))
 	    (forward-line)
-	    (when (looking-at "Total number of bytes: \\([[:digit:]]+\\)")
+	    (when (looking-at (rx "Total number of bytes: " (group (+ digit))))
 	      ;; The used number of bytes is not part of the result.
 	      ;; As side effect, we store it as file property.
 	      (tramp-set-file-property
@@ -1061,11 +1068,11 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 		(/ (tramp-get-file-property v localname "used-bytes" 0) 1024))))
 
 	  (when wildcard
-	    (string-match "\\." base)
+	    (string-match (rx ".") base)
 	    (setq base (replace-match "\\\\." nil nil base))
-	    (string-match "\\*" base)
+	    (string-match (rx "*") base)
 	    (setq base (replace-match ".*" nil nil base))
-	    (string-match "\\?" base)
+	    (string-match (rx "?") base)
 	    (setq base (replace-match ".?" nil nil base)))
 
 	  ;; Filter entries.
@@ -1076,7 +1083,8 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 		     ;; Check for matching entries.
 		     (mapcar
 		      (lambda (x)
-			(when (string-match-p (format "^%s" base) (nth 0 x)) x))
+			(when (string-match-p (rx bol (literal base)) (nth 0 x))
+			  x))
 		      entries)
 		   ;; We just need the only and only entry FILENAME.
 		   (list (assoc base entries)))))
@@ -1486,7 +1494,7 @@ component is used as the target of the symlink."
 		    ;; the function.  No error is propagated outside,
 		    ;; due to the `ignore-errors' closure.
 		    (unless
-			(tramp-search-regexp "tramp_exit_status [[:digit:]]+")
+			(tramp-search-regexp (rx "tramp_exit_status " (+ digit)))
 		      (tramp-error
 		       v 'file-error
 		       "Couldn't find exit status of `%s'"
@@ -1577,7 +1585,8 @@ errors for shares like \"C$/\", which are common in Microsoft Windows."
       filename
     (with-parsed-tramp-file-name filename nil
       ;; Ignore in LOCALNAME everything before "//".
-      (when (and (stringp localname) (string-match ".+?/\\(/\\|~\\)" localname))
+      (when (and (stringp localname)
+		 (string-match (rx (+? nonl) "/" (group (| "/" "~"))) localname))
 	(setq filename
 	      (concat (file-remote-p filename)
 		      (replace-match "\\1" nil nil localname)))))
@@ -1623,7 +1632,8 @@ VEC or USER, or if there is no home directory, return nil."
   "Return the share name of LOCALNAME."
   (save-match-data
     (let ((localname (tramp-file-name-unquote-localname vec)))
-      (when (string-match "^/?\\([^/]+\\)/" localname)
+      (when (string-match
+	     (rx bol (? "/") (group (+ (not (any "/")))) "/") localname)
 	(match-string 1 localname)))))
 
 (defun tramp-smb-get-localname (vec)
@@ -1633,7 +1643,8 @@ If VEC has no cifs capabilities, exchange \"/\" by \"\\\\\"."
     (let ((localname (tramp-file-name-unquote-localname vec)))
       (setq
        localname
-       (if (string-match "^/?[^/]+\\(/.*\\)" localname)
+       (if (string-match
+	    (rx bol (? "/") (+ (not (any "/"))) (group "/" (* nonl))) localname)
 	   ;; There is a share, separated by "/".
 	   (if (not (tramp-smb-get-cifs-capabilities vec))
 	       (mapconcat
@@ -1641,16 +1652,17 @@ If VEC has no cifs capabilities, exchange \"/\" by \"\\\\\"."
 		(match-string 1 localname) "")
 	     (match-string 1 localname))
 	 ;; There is just a share.
-	 (if (string-match "^/?\\([^/]+\\)$" localname)
+	 (if (string-match
+	      (rx bol (? "/") (group (+ (not (any "/")))) eol) localname)
 	     (match-string 1 localname)
 	   "")))
 
       ;; Sometimes we have discarded `substitute-in-file-name'.
-      (when (string-match "\\(\\$\\$\\)\\(/\\|$\\)" localname)
+      (when (string-match (rx (group "$$") (group (| "/" eol))) localname)
 	(setq localname (replace-match "$" nil nil localname 1)))
 
       ;; A trailing space is not supported.
-      (when (string-match-p " $" localname)
+      (when (string-match-p (rx " " eol) localname)
 	(tramp-error
 	 vec 'file-error
 	 "Invalid file name %s" (tramp-make-tramp-file-name vec localname)))
@@ -1769,7 +1781,8 @@ are listed.  Result is the list (LOCALNAME MODE SIZE MTIME)."
     (if (not share)
 
 	;; Read share entries.
-	(when (string-match "^Disk|\\([^|]+\\)|" line)
+	(when (string-match
+	       (rx bol "Disk|" (group (+ (not (any "|")))) "|") line)
 	  (setq localname (match-string 1 line)
 		mode "dr-xr-xr-x"
 		size 0))
@@ -1778,14 +1791,17 @@ are listed.  Result is the list (LOCALNAME MODE SIZE MTIME)."
       (cl-block nil
 
 	;; year.
-	(if (string-match "\\([[:digit:]]+\\)$" line)
+	(if (string-match (rx (group (+ digit)) eol) line)
 	    (setq year (string-to-number (match-string 1 line))
 		  line (substring line 0 -5))
 	  (cl-return))
 
 	;; time.
 	(if (string-match
-	     "\\([[:digit:]]+\\):\\([[:digit:]]+\\):\\([[:digit:]]+\\)$" line)
+	     (rx (group (+ digit)) ":"
+		 (group (+ digit)) ":"
+		 (group (+ digit)) eol)
+	     line)
 	    (setq hour (string-to-number (match-string 1 line))
 		  min  (string-to-number (match-string 2 line))
 		  sec  (string-to-number (match-string 3 line))
@@ -1793,28 +1809,28 @@ are listed.  Result is the list (LOCALNAME MODE SIZE MTIME)."
 	  (cl-return))
 
 	;; day.
-	(if (string-match "\\([[:digit:]]+\\)$" line)
+	(if (string-match (rx (group (+ digit)) eol) line)
 	    (setq day  (string-to-number (match-string 1 line))
 		  line (substring line 0 -3))
 	  (cl-return))
 
 	;; month.
-	(if (string-match "\\(\\w+\\)$" line)
+	(if (string-match (rx (group (+ wordchar)) eol) line)
 	    (setq month (match-string 1 line)
 		  line  (substring line 0 -4))
 	  (cl-return))
 
 	;; weekday.
-	(if (string-match-p "\\(\\w+\\)$" line)
+	(if (string-match-p (rx (group (+ wordchar)) eol) line)
 	    (setq line (substring line 0 -5))
 	  (cl-return))
 
 	;; size.
-	(if (string-match "\\([[:digit:]]+\\)$" line)
+	(if (string-match (rx (group (+ digit)) eol) line)
 	    (let ((length (- (max 10 (1+ (length (match-string 1 line)))))))
 	      (setq size (string-to-number (match-string 1 line)))
 	      (when (string-match
-		     "\\([ACDEHNORrsSTV]+\\)" (substring line length))
+		     (rx (+ (any "ACDEHNORSTVrs"))) (substring line length))
 		(setq length (+ length (match-end 0))))
 	      (setq line (substring line 0 length)))
 	  (cl-return))
@@ -1823,7 +1839,7 @@ are listed.  Result is the list (LOCALNAME MODE SIZE MTIME)."
 	;;       NONINDEXED, NORMAL, OFFLINE, READONLY,
 	;;       REPARSE_POINT, SPARSE, SYSTEM, TEMPORARY, VOLID.
 
-	(if (string-match "\\([ACDEHNORrsSTV]+\\)?$" line)
+	(if (string-match (rx (? (group (+ (any "ACDEHNORSTVrs")))) eol) line)
 	    (setq
 	     mode (or (match-string 1 line) "")
 	     mode (format
@@ -1838,7 +1854,11 @@ are listed.  Result is the list (LOCALNAME MODE SIZE MTIME)."
 	  (cl-return))
 
 	;; localname.
-	(if (string-match "^\\s-+\\(\\S-\\(.*\\S-\\)?\\)\\s-*$" line)
+	(if (string-match
+	     (rx bol (+ space)
+		 (group (not space) (? (group (* nonl) (not space))))
+		 (* space) eol)
+	     line)
 	    (setq localname (match-string 1 line))
 	  (cl-return))))
 
@@ -1877,7 +1897,8 @@ are listed.  Result is the list (LOCALNAME MODE SIZE MTIME)."
 		(member
 		 "pathnames"
 		 (split-string
-                  (buffer-substring (point) (line-end-position)) nil 'omit)))))))))
+		  (buffer-substring (point) (line-end-position))
+		  nil 'omit)))))))))
 
 (defun tramp-smb-get-stat-capability (vec)
   "Check whether the SMB server supports the `stat' command."
@@ -1927,7 +1948,7 @@ If ARGUMENT is non-nil, use it as argument for
 	  (setq tramp-smb-version (shell-command-to-string command))
 	  (tramp-message vec 6 command)
 	  (tramp-message vec 6 "\n%s" tramp-smb-version)
-	  (if (string-match "[ \t\n\r]+\\'" tramp-smb-version)
+	  (if (string-match (rx (+ (any " \t\n\r")) eos) tramp-smb-version)
 	      (setq tramp-smb-version
 		    (replace-match "" nil nil tramp-smb-version))))
 
diff --git a/lisp/net/tramp-sshfs.el b/lisp/net/tramp-sshfs.el
index 4e3b94277be..31720a605ec 100644
--- a/lisp/net/tramp-sshfs.el
+++ b/lisp/net/tramp-sshfs.el
@@ -215,7 +215,7 @@ arguments to pass to the OPERATION."
 	  (progn
 	    ;; Read the expression.
 	    (goto-char (point-min))
-            (buffer-substring (point) (line-end-position)))
+	    (buffer-substring (point) (line-end-position)))
 	  ":" 'omit))))
    ;; The equivalent to `exec-directory'.
    `(,(tramp-file-local-name (expand-file-name default-directory)))))
diff --git a/lisp/net/tramp-sudoedit.el b/lisp/net/tramp-sudoedit.el
index 643b5f35c0f..893afcdbbee 100644
--- a/lisp/net/tramp-sudoedit.el
+++ b/lisp/net/tramp-sudoedit.el
@@ -49,7 +49,8 @@
 		(tramp-password-previous-hop t)))
 
  (add-to-list 'tramp-default-user-alist
-	      `("\\`sudoedit\\'" nil ,tramp-root-id-string))
+	      `(,(rx bos (literal tramp-sudoedit-method) eos)
+		nil ,tramp-root-id-string))
 
  (tramp-set-completion-function
   tramp-sudoedit-method tramp-completion-function-alist-su))
@@ -374,7 +375,9 @@ the result will be a local, non-Tramp, file name."
       (setq localname "~"))
     (unless (file-name-absolute-p localname)
       (setq localname (format "~%s/%s" user localname)))
-    (when (string-match "\\`~\\([^/]*\\)\\(.*\\)\\'" localname)
+    (when (string-match
+	   (rx bos "~" (group (* (not (any "/")))) (group (* nonl)) eos)
+	   localname)
       (let ((uname (match-string 1 localname))
 	    (fname (match-string 2 localname))
 	    hname)
@@ -383,11 +386,11 @@ the result will be a local, non-Tramp, file name."
 	(when (setq hname (tramp-get-home-directory v uname))
 	  (setq localname (concat hname fname)))))
     ;; Do not keep "/..".
-    (when (string-match-p "^/\\.\\.?$" localname)
+    (when (string-match-p (rx bos "/" (** 1 2 ".") eos) localname)
       (setq localname "/"))
     ;; Do normal `expand-file-name' (this does "~user/", "/./" and "/../").
     (tramp-make-tramp-file-name
-     v (if (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname)
+     v (if (string-prefix-p "~" localname)
 	   localname
 	 (tramp-run-real-handler
 	  #'expand-file-name (list localname))))))
@@ -470,7 +473,7 @@ the result will be a local, non-Tramp, file name."
 	(delq
 	 nil
 	 (mapcar
-	  (lambda (l) (and (not (string-match-p "^[[:space:]]*$" l)) l))
+	  (lambda (l) (and (not (string-match-p (rx bol (* space) eol) l)) l))
 	  (split-string
 	   (tramp-get-buffer-string (tramp-get-connection-buffer v))
 	   "\n" 'omit))))))))
@@ -504,15 +507,17 @@ the result will be a local, non-Tramp, file name."
   (with-parsed-tramp-file-name filename nil
     (with-tramp-file-property v localname "file-selinux-context"
       (let ((context '(nil nil nil nil))
-	    (regexp (concat "\\([[:alnum:]_]+\\):" "\\([[:alnum:]_]+\\):"
-			    "\\([[:alnum:]_]+\\):" "\\([[:alnum:]_]+\\)")))
+	    (regexp (rx (group (+ (any "_" alnum))) ":"
+			(group (+ (any "_" alnum))) ":"
+			(group (+ (any "_" alnum))) ":"
+			(group (+ (any "_" alnum))))))
 	(when (and (tramp-sudoedit-remote-selinux-p v)
 		   (tramp-sudoedit-send-command
 		    v "ls" "-d" "-Z"
 		    (tramp-compat-file-name-unquote localname)))
 	  (with-current-buffer (tramp-get-connection-buffer v)
 	    (goto-char (point-min))
-            (when (re-search-forward regexp (line-end-position) t)
+	    (when (re-search-forward regexp (line-end-position) t)
 	      (setq context (list (match-string 1) (match-string 2)
 				  (match-string 3) (match-string 4))))))
 	;; Return the context.
@@ -530,9 +535,9 @@ the result will be a local, non-Tramp, file name."
 	  (goto-char (point-min))
 	  (forward-line)
 	  (when (looking-at
-		 (concat "[[:space:]]*\\([[:digit:]]+\\)"
-			 "[[:space:]]+\\([[:digit:]]+\\)"
-			 "[[:space:]]+\\([[:digit:]]+\\)"))
+		 (rx (* space) (group (+ digit))
+		     (+ space) (group (+ digit))
+		     (+ space) (group (+ digit))))
 	    (list (string-to-number (match-string 1))
 		  ;; The second value is the used size.  We need the
 		  ;; free size.
@@ -841,7 +846,7 @@ In case there is no valid Lisp expression, it raises an error."
       (condition-case nil
 	  (prog1 (read (current-buffer))
 	    ;; Error handling.
-            (when (re-search-forward "\\S-" (line-end-position) t)
+	    (when (re-search-forward (rx (not space)) (line-end-position) t)
 	      (error nil)))
 	(error (tramp-error
 		vec 'file-error
@@ -855,7 +860,7 @@ In case there is no valid Lisp expression, it raises an error."
       (tramp-message vec 6 "\n%s" (buffer-string))
       (goto-char (point-max))
       ;(delete-blank-lines)
-      (while (looking-back "[ \t\n]+" nil 'greedy)
+      (while (looking-back (rx (+ (any " \t\n"))) nil 'greedy)
 	(delete-region (match-beginning 0) (point)))
       (when (> (point-max) (point-min))
 	(substring-no-properties (buffer-string))))))
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 238ec50c40f..bb6eeaa7417 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -64,7 +64,8 @@
 (declare-function netrc-parse "netrc")
 (defvar auto-save-file-name-transforms)
 
-;; Reload `tramp-compat' when we reload `tramp-autoloads' of the GNU ELPA package.
+;; Reload `tramp-compat' when we reload `tramp-autoloads' of the GNU
+;; ELPA package.
 ;;;###autoload (when (featurep 'tramp-compat)
 ;;;###autoload   (load "tramp-compat" 'noerror 'nomessage))
 
@@ -514,10 +515,10 @@ interpreted as a regular expression which always matches."
 ;; <https://debbugs.gnu.org/cgi/bugreport.cgi?bug=38079#20>.
 (defcustom tramp-restricted-shell-hosts-alist
   (when (and (eq system-type 'windows-nt)
-             (not (string-match-p "sh$" tramp-encoding-shell)))
-    (list (format "\\`\\(%s\\|%s\\)\\'"
-		  (regexp-quote (downcase tramp-system-name))
-		  (regexp-quote (upcase tramp-system-name)))))
+             (not (string-match-p (rx "sh" eol) tramp-encoding-shell)))
+    (list (rx bos (group (| (literal (downcase tramp-system-name))
+			    (literal (upcase tramp-system-name))))
+	      eos)))
   "List of hosts, which run a restricted shell.
 This is a list of regular expressions, which denote hosts running
 a restricted shell like \"rbash\".  Those hosts can be used as
@@ -528,12 +529,11 @@ host runs a restricted shell, it shall be added to this list, too."
 
 ;;;###tramp-autoload
 (defcustom tramp-local-host-regexp
-  (concat
-   "\\`"
-   (regexp-opt
-    `("localhost" "localhost4" "localhost6" ,tramp-system-name "127.0.0.1" "::1")
-    t)
-   "\\'")
+  (rx bos
+      (regexp (regexp-opt
+	       `("localhost" "localhost4" "localhost6"
+		 ,tramp-system-name "127.0.0.1" "::1")))
+      eos)
   "Host names which are regarded as local host.
 If the local host runs a chrooted environment, set this to nil."
   :version "29.1"
@@ -580,8 +580,9 @@ followed by an equal number of backspaces to erase them will
 usually suffice.")
 
 (defconst tramp-echoed-echo-mark-regexp
-  (format "%s\\(\b\\( \b\\)?\\)\\{%d\\}"
-	  tramp-echo-mark-marker tramp-echo-mark-marker-length)
+  (rx-to-string
+   `(: ,tramp-echo-mark-marker
+       (= ,tramp-echo-mark-marker-length (group "\b" (? " \b")))))
   "Regexp which matches `tramp-echo-mark' as it gets echoed by \
 the remote shell.")
 
@@ -598,7 +599,7 @@ if you need to change this."
   :type 'string)
 
 (defcustom tramp-login-prompt-regexp
-  ".*\\(user\\|login\\)\\( .*\\)?: *"
+  (rx (* nonl) (group (| "user" "login")) (? (group " " (* nonl))) ":" (* " "))
   "Regexp matching login-like prompts.
 The regexp should match at end of buffer.
 
@@ -610,8 +611,11 @@ Sometimes the prompt is reported to look like \"login as:\"."
   ;; displayed at the beginning of the line (and Zsh uses it).
   ;; Allow also [] style prompts.  They can appear only during
   ;; connection initialization; Tramp redefines the prompt afterwards.
-  (concat "\\(?:^\\|\r\\)"
-	  "[^]#$%>\n]*#?[]#$%>] *\\(\e\\[[[:digit:];]*[[:alpha:]] *\\)*")
+  (rx (| bol "\r")
+      (* (not (any "\n#$%>]")))
+      (? "#") (any "#$%>]") (* space)
+      ;; Escape characters.
+      (* "[" (* (any ";" digit)) alpha (* space)))
   "Regexp to match prompts from remote shell.
 Normally, Tramp expects you to configure `shell-prompt-pattern'
 correctly, but sometimes it happens that you are connecting to a
@@ -626,7 +630,9 @@ This regexp must match both `tramp-initial-end-of-output' and
   :type 'regexp)
 
 (defcustom tramp-password-prompt-regexp
-  (format "^.*\\(%s\\).*:\^@? *" (regexp-opt password-word-equivalents))
+  (rx bol (* nonl)
+      (group (regexp (regexp-opt password-word-equivalents)))
+      (* nonl) ":" (? "\^@") (* space))
   "Regexp matching password-like prompts.
 The regexp should match at end of buffer.
 
@@ -640,36 +646,26 @@ The `sudo' program appears to insert a `^@' character into the prompt."
   :type 'regexp)
 
 (defcustom tramp-wrong-passwd-regexp
-  (concat "^.*"
-	  ;; These strings should be on the last line
-	  (regexp-opt '("Permission denied"
-			"Login incorrect"
-			"Login Incorrect"
-			"Connection refused"
-			"Connection closed"
-			"Timeout, server not responding."
-			"Sorry, try again."
-			"Name or service not known"
-			"Host key verification failed."
-			"No supported authentication methods left to try!")
-		      t)
-	  ".*"
-	  "\\|"
-	  "^.*\\("
-	  ;; Here comes a list of regexes, separated by \\|
-	  "Received signal [[:digit:]]+"
-	  "\\).*")
+  (rx bol (* nonl)
+      (| "Permission denied"
+	 "Login [Ii]ncorrect"
+	 "Connection refused"
+	 "Connection closed"
+	 "Timeout, server not responding."
+	 "Sorry, try again."
+	 "Name or service not known"
+	 "Host key verification failed."
+	 "No supported authentication methods left to try!"
+	 (: "Received signal " (+ digit)))
+      (* nonl))
   "Regexp matching a `login failed' message.
 The regexp should match at end of buffer."
   :type 'regexp)
 
 (defcustom tramp-yesno-prompt-regexp
-  (concat
-   (regexp-opt
-    '("Are you sure you want to continue connecting (yes/no)?"
-      "Are you sure you want to continue connecting (yes/no/[fingerprint])?")
-    t)
-   "\\s-*")
+  (rx "Are you sure you want to continue connecting (yes/no"
+      (? "/[fingerprint]") ")?"
+      (* space))
   "Regular expression matching all yes/no queries which need to be confirmed.
 The confirmation should be done with yes or no.
 The regexp should match at end of buffer.
@@ -677,11 +673,9 @@ See also `tramp-yn-prompt-regexp'."
   :type 'regexp)
 
 (defcustom tramp-yn-prompt-regexp
-  (concat
-   (regexp-opt '("Store key in cache? (y/n)"
-		 "Update cached key? (y/n, Return cancels connection)")
-               t)
-   "\\s-*")
+  (rx (| "Store key in cache? (y/n)"
+	 "Update cached key? (y/n, Return cancels connection)")
+      (* space))
   "Regular expression matching all y/n queries which need to be confirmed.
 The confirmation should be done with y or n.
 The regexp should match at end of buffer.
@@ -698,11 +692,10 @@ files conditionalize this setup based on the TERM environment variable."
   :type 'string)
 
 (defcustom tramp-terminal-prompt-regexp
-  (concat "\\("
-	  "TERM = (.*)"
-	  "\\|"
-	  "Terminal type\\? \\[.*\\]"
-	  "\\)\\s-*")
+  (rx (group
+       (| (: "TERM = (" (* nonl) ")")
+	  (: "Terminal type? [" (* nonl) "]")))
+      (* space))
   "Regular expression matching all terminal setting prompts.
 The regexp should match at end of buffer.
 The answer will be provided by `tramp-action-terminal', which see."
@@ -713,7 +706,7 @@ The answer will be provided by `tramp-action-terminal', which see."
 ;; "-no-antispoof".  However, since we don't know which PuTTY
 ;; version is installed, we must react interactively.
 (defcustom tramp-antispoof-regexp
-  (regexp-quote "Access granted. Press Return to begin session. ")
+  (rx (literal "Access granted. Press Return to begin session. "))
   "Regular expression matching plink's anti-spoofing message.
 The regexp should match at end of buffer."
   :version "27.1"
@@ -723,42 +716,42 @@ The regexp should match at end of buffer."
 ;; with their finger.  We must tell it to the user.
 ;; Added in OpenSSH 8.2.  I've tested it with yubikey.
 (defcustom tramp-security-key-confirm-regexp
-  "^\r*Confirm user presence for key .*[\r\n]*"
+  (rx bol (* "\r") "Confirm user presence for key " (* nonl) (* (any "\r\n")))
   "Regular expression matching security key confirmation message.
 The regexp should match at end of buffer."
   :version "28.1"
   :type 'regexp)
 
 (defcustom tramp-security-key-confirmed-regexp
-  "^\r*User presence confirmed[\r\n]*"
+  (rx bol (* "\r") "User presence confirmed" (* (any "\r\n")))
   "Regular expression matching security key confirmation message.
 The regexp should match at end of buffer."
   :version "28.1"
   :type 'regexp)
 
 (defcustom tramp-security-key-timeout-regexp
-  "^\r*sign_and_send_pubkey: signing failed for .*[\r\n]*"
+  (rx bol (* "\r") "sign_and_send_pubkey: signing failed for "
+      (* nonl) (* (any "\r\n")))
   "Regular expression matching security key timeout message.
 The regexp should match at end of buffer."
   :version "28.1"
   :type 'regexp)
 
 (defcustom tramp-operation-not-permitted-regexp
-  (concat "\\(" "preserving times.*" "\\|" "set mode" "\\)" ":\\s-*"
-	  (regexp-opt '("Operation not permitted") t))
+  (rx (| (: "preserving times" (* nonl)) "set mode") ":" (* space)
+      "Operation not permitted")
   "Regular expression matching keep-date problems in (s)cp operations.
 Copying has been performed successfully already, so this message can
 be ignored safely."
   :type 'regexp)
 
 (defcustom tramp-copy-failed-regexp
-  (concat "\\(.+: "
-          (regexp-opt '("Permission denied"
-                        "not a regular file"
-                        "is a directory"
-                        "No such file or directory")
-                      t)
-          "\\)\\s-*")
+  (rx (+ nonl) ": "
+      (| "No such file or directory"
+	 "Permission denied"
+	 "is a directory"
+	 "not a regular file")
+      (* space))
   "Regular expression matching copy problems in (s)cp operations."
   :type 'regexp)
 
@@ -809,6 +802,23 @@ Customize.  See also `tramp-change-syntax'."
   :initialize #'custom-initialize-default
   :set #'tramp-set-syntax)
 
+(defvar tramp-prefix-format)
+(defvar tramp-prefix-regexp)
+(defvar tramp-method-regexp)
+(defvar tramp-postfix-method-format)
+(defvar tramp-postfix-method-regexp)
+(defvar tramp-prefix-ipv6-format)
+(defvar tramp-prefix-ipv6-regexp)
+(defvar tramp-postfix-ipv6-format)
+(defvar tramp-postfix-ipv6-regexp)
+(defvar tramp-postfix-host-format)
+(defvar tramp-postfix-host-regexp)
+(defvar tramp-remote-file-name-spec-regexp)
+(defvar tramp-file-name-structure)
+(defvar tramp-file-name-regexp)
+(defvar tramp-completion-method-regexp)
+(defvar tramp-completion-file-name-regexp)
+
 (defun tramp-set-syntax (symbol value)
   "Set SYMBOL to value VALUE.
 Used in user option `tramp-syntax'.  There are further variables
@@ -822,24 +832,25 @@ to be set, depending on VALUE."
   ;; Set the value:
   (set-default symbol value)
   ;; Reset the depending variables.
-  (with-no-warnings
-    (setq tramp-prefix-format (tramp-build-prefix-format)
-	  tramp-prefix-regexp (tramp-build-prefix-regexp)
-	  tramp-method-regexp (tramp-build-method-regexp)
-	  tramp-postfix-method-format (tramp-build-postfix-method-format)
-	  tramp-postfix-method-regexp (tramp-build-postfix-method-regexp)
-	  tramp-prefix-ipv6-format (tramp-build-prefix-ipv6-format)
-	  tramp-prefix-ipv6-regexp (tramp-build-prefix-ipv6-regexp)
-	  tramp-postfix-ipv6-format (tramp-build-postfix-ipv6-format)
-	  tramp-postfix-ipv6-regexp (tramp-build-postfix-ipv6-regexp)
-	  tramp-postfix-host-format (tramp-build-postfix-host-format)
-	  tramp-postfix-host-regexp (tramp-build-postfix-host-regexp)
-	  tramp-remote-file-name-spec-regexp
-	  (tramp-build-remote-file-name-spec-regexp)
-	  tramp-file-name-structure (tramp-build-file-name-structure)
-	  tramp-file-name-regexp (tramp-build-file-name-regexp)
-	  tramp-completion-file-name-regexp
-          (tramp-build-completion-file-name-regexp)))
+  (setq tramp-prefix-format (tramp-build-prefix-format)
+	tramp-prefix-regexp (tramp-build-prefix-regexp)
+	tramp-method-regexp (tramp-build-method-regexp)
+	tramp-postfix-method-format (tramp-build-postfix-method-format)
+	tramp-postfix-method-regexp (tramp-build-postfix-method-regexp)
+	tramp-prefix-ipv6-format (tramp-build-prefix-ipv6-format)
+	tramp-prefix-ipv6-regexp (tramp-build-prefix-ipv6-regexp)
+	tramp-postfix-ipv6-format (tramp-build-postfix-ipv6-format)
+	tramp-postfix-ipv6-regexp (tramp-build-postfix-ipv6-regexp)
+	tramp-postfix-host-format (tramp-build-postfix-host-format)
+	tramp-postfix-host-regexp (tramp-build-postfix-host-regexp)
+	tramp-remote-file-name-spec-regexp
+	(tramp-build-remote-file-name-spec-regexp)
+	tramp-file-name-structure (tramp-build-file-name-structure)
+	tramp-file-name-regexp (tramp-build-file-name-regexp)
+	tramp-completion-method-regexp
+        (tramp-build-completion-method-regexp)
+	tramp-completion-file-name-regexp
+        (tramp-build-completion-file-name-regexp))
   ;; Rearrange file name handlers.
   (tramp-register-file-name-handlers))
 
@@ -872,30 +883,31 @@ Raise an error if it is invalid."
   "Return `tramp-prefix-format' according to `tramp-syntax'."
   (tramp-lookup-syntax tramp-prefix-format-alist))
 
-(defvar tramp-prefix-format nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-prefix-format nil ; Initialized when defining `tramp-syntax'!
   "String matching the very beginning of Tramp file names.
 Used in `tramp-make-tramp-file-name'.")
 
 (defun tramp-build-prefix-regexp ()
   "Return `tramp-prefix-regexp'."
-  (concat "^" (regexp-quote tramp-prefix-format)))
+  (rx bol (literal (tramp-build-prefix-format))))
 
-(defvar tramp-prefix-regexp nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-prefix-regexp nil ; Initialized when defining `tramp-syntax'!
   "Regexp matching the very beginning of Tramp file names.
 Should always start with \"^\".  Derived from `tramp-prefix-format'.")
 
 (defconst tramp-method-regexp-alist
-  '((default    . "[[:alnum:]-]+")
+  `((default . ,(rx (| (literal tramp-default-method-marker) (>= 2 alnum))))
     (simplified . "")
-    (separate   . "[[:alnum:]-]*"))
+    (separate
+     . ,(rx (? (| (literal tramp-default-method-marker) (>= 2 alnum))))))
   "Alist mapping Tramp syntax to regexps matching methods identifiers.")
 
 (defun tramp-build-method-regexp ()
   "Return `tramp-method-regexp' according to `tramp-syntax'."
   (tramp-lookup-syntax tramp-method-regexp-alist))
 
-(defvar tramp-method-regexp nil ;Initialized when defining `tramp-syntax'!
-  "Regexp matching methods identifiers.
+(defvar tramp-method-regexp nil ; Initialized when defining `tramp-syntax'!
+  "Regexp matching method identifiers.
 The `ftp' syntax does not support methods.")
 
 (defconst tramp-postfix-method-format-alist
@@ -908,47 +920,47 @@ The `ftp' syntax does not support methods.")
   "Return `tramp-postfix-method-format' according to `tramp-syntax'."
   (tramp-lookup-syntax tramp-postfix-method-format-alist))
 
-(defvar tramp-postfix-method-format nil ;Init'd when defining `tramp-syntax'!
+(defvar tramp-postfix-method-format nil ; Init'd when defining `tramp-syntax'!
   "String matching delimiter between method and user or host names.
 The `ftp' syntax does not support methods.
 Used in `tramp-make-tramp-file-name'.")
 
 (defun tramp-build-postfix-method-regexp ()
   "Return `tramp-postfix-method-regexp'."
-  (regexp-quote tramp-postfix-method-format))
+  (rx (literal (tramp-build-postfix-method-format))))
 
-(defvar tramp-postfix-method-regexp nil ;Init'd when defining `tramp-syntax'!
+(defvar tramp-postfix-method-regexp nil ; Init'd when defining `tramp-syntax'!
   "Regexp matching delimiter between method and user or host names.
 Derived from `tramp-postfix-method-format'.")
 
-(defconst tramp-user-regexp "[^/|: \t]+"
+(defconst tramp-user-regexp (rx (+ (not (any "/:|" space))))
   "Regexp matching user names.")
 
 (defconst tramp-prefix-domain-format "%"
   "String matching delimiter between user and domain names.")
 
-(defconst tramp-prefix-domain-regexp (regexp-quote tramp-prefix-domain-format)
+(defconst tramp-prefix-domain-regexp (rx (literal tramp-prefix-domain-format))
   "Regexp matching delimiter between user and domain names.
 Derived from `tramp-prefix-domain-format'.")
 
-(defconst tramp-domain-regexp "[[:alnum:]_.-]+"
+(defconst tramp-domain-regexp (rx (+ (any "._-" alnum)))
   "Regexp matching domain names.")
 
 (defconst tramp-user-with-domain-regexp
-  (concat "\\(" tramp-user-regexp "\\)"
-	        tramp-prefix-domain-regexp
-	  "\\(" tramp-domain-regexp "\\)")
+  (rx (group (regexp tramp-user-regexp))
+             (regexp tramp-prefix-domain-regexp)
+      (group (regexp tramp-domain-regexp)))
   "Regexp matching user names with domain names.")
 
 (defconst tramp-postfix-user-format "@"
   "String matching delimiter between user and host names.
 Used in `tramp-make-tramp-file-name'.")
 
-(defconst tramp-postfix-user-regexp (regexp-quote tramp-postfix-user-format)
+(defconst tramp-postfix-user-regexp (rx (literal tramp-postfix-user-format))
   "Regexp matching delimiter between user and host names.
 Derived from `tramp-postfix-user-format'.")
 
-(defconst tramp-host-regexp "[[:alnum:]_.%-]+"
+(defconst tramp-host-regexp (rx (+ (any "%._-" alnum)))
   "Regexp matching host names.")
 
 (defconst tramp-prefix-ipv6-format-alist
@@ -961,22 +973,22 @@ Derived from `tramp-postfix-user-format'.")
   "Return `tramp-prefix-ipv6-format' according to `tramp-syntax'."
   (tramp-lookup-syntax tramp-prefix-ipv6-format-alist))
 
-(defvar tramp-prefix-ipv6-format nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-prefix-ipv6-format nil ; Initialized when defining `tramp-syntax'!
   "String matching left hand side of IPv6 addresses.
 Used in `tramp-make-tramp-file-name'.")
 
 (defun tramp-build-prefix-ipv6-regexp ()
   "Return `tramp-prefix-ipv6-regexp'."
-  (regexp-quote tramp-prefix-ipv6-format))
+  (rx (literal tramp-prefix-ipv6-format)))
 
-(defvar tramp-prefix-ipv6-regexp nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-prefix-ipv6-regexp nil ; Initialized when defining `tramp-syntax'!
   "Regexp matching left hand side of IPv6 addresses.
 Derived from `tramp-prefix-ipv6-format'.")
 
 ;; The following regexp is a bit sloppy.  But it shall serve our
 ;; purposes.  It covers also IPv4 mapped IPv6 addresses, like in
 ;; "::ffff:192.168.0.1".
-(defconst tramp-ipv6-regexp "\\(?:[[:alnum:]]*:\\)+[[:alnum:].]+"
+(defconst tramp-ipv6-regexp (rx (+ (* alnum) ":") (* (any "." alnum)))
   "Regexp matching IPv6 addresses.")
 
 (defconst tramp-postfix-ipv6-format-alist
@@ -989,38 +1001,38 @@ Derived from `tramp-prefix-ipv6-format'.")
   "Return `tramp-postfix-ipv6-format' according to `tramp-syntax'."
   (tramp-lookup-syntax tramp-postfix-ipv6-format-alist))
 
-(defvar tramp-postfix-ipv6-format nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-postfix-ipv6-format nil ; Initialized when defining `tramp-syntax'!
   "String matching right hand side of IPv6 addresses.
 Used in `tramp-make-tramp-file-name'.")
 
 (defun tramp-build-postfix-ipv6-regexp ()
   "Return `tramp-postfix-ipv6-regexp'."
-  (regexp-quote tramp-postfix-ipv6-format))
+  (rx (literal tramp-postfix-ipv6-format)))
 
-(defvar tramp-postfix-ipv6-regexp nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-postfix-ipv6-regexp nil ; Initialized when defining `tramp-syntax'!
   "Regexp matching right hand side of IPv6 addresses.
 Derived from `tramp-postfix-ipv6-format'.")
 
 (defconst tramp-prefix-port-format "#"
   "String matching delimiter between host names and port numbers.")
 
-(defconst tramp-prefix-port-regexp (regexp-quote tramp-prefix-port-format)
+(defconst tramp-prefix-port-regexp (rx (literal tramp-prefix-port-format))
   "Regexp matching delimiter between host names and port numbers.
 Derived from `tramp-prefix-port-format'.")
 
-(defconst tramp-port-regexp "[[:digit:]]+"
+(defconst tramp-port-regexp (rx (+ digit))
   "Regexp matching port numbers.")
 
 (defconst tramp-host-with-port-regexp
-  (concat "\\(" tramp-host-regexp "\\)"
-	        tramp-prefix-port-regexp
-	  "\\(" tramp-port-regexp "\\)")
+  (rx (group (regexp tramp-host-regexp))
+             (regexp tramp-prefix-port-regexp)
+      (group (regexp tramp-port-regexp)))
   "Regexp matching host names with port numbers.")
 
 (defconst tramp-postfix-hop-format "|"
   "String matching delimiter after ad-hoc hop definitions.")
 
-(defconst tramp-postfix-hop-regexp (regexp-quote tramp-postfix-hop-format)
+(defconst tramp-postfix-hop-regexp (rx (literal tramp-postfix-hop-format))
   "Regexp matching delimiter after ad-hoc hop definitions.
 Derived from `tramp-postfix-hop-format'.")
 
@@ -1034,19 +1046,19 @@ Derived from `tramp-postfix-hop-format'.")
   "Return `tramp-postfix-host-format' according to `tramp-syntax'."
   (tramp-lookup-syntax tramp-postfix-host-format-alist))
 
-(defvar tramp-postfix-host-format nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-postfix-host-format nil ; Initialized when defining `tramp-syntax'!
   "String matching delimiter between host names and localnames.
 Used in `tramp-make-tramp-file-name'.")
 
 (defun tramp-build-postfix-host-regexp ()
   "Return `tramp-postfix-host-regexp'."
-  (regexp-quote tramp-postfix-host-format))
+  (rx (literal tramp-postfix-host-format)))
 
-(defvar tramp-postfix-host-regexp nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-postfix-host-regexp nil ; Initialized when defining `tramp-syntax'!
   "Regexp matching delimiter between host names and localnames.
 Derived from `tramp-postfix-host-format'.")
 
-(defconst tramp-localname-regexp "[^\n\r]*\\'"
+(defconst tramp-localname-regexp (rx (* (not (any "\r\n"))) eos)
   "Regexp matching localnames.")
 
 (defconst tramp-unknown-id-string "UNKNOWN"
@@ -1067,16 +1079,20 @@ Derived from `tramp-postfix-host-format'.")
 (defun tramp-build-remote-file-name-spec-regexp ()
   "Construct a regexp matching a Tramp file name for a Tramp syntax.
 It is expected, that `tramp-syntax' has the proper value."
-  (concat
-           "\\("   tramp-method-regexp "\\)" tramp-postfix-method-regexp
-   "\\(?:" "\\("   tramp-user-regexp   "\\)" tramp-postfix-user-regexp   "\\)?"
-   "\\("   "\\(?:" tramp-host-regexp   "\\|"
-	           tramp-prefix-ipv6-regexp  "\\(?:" tramp-ipv6-regexp "\\)?"
-					     tramp-postfix-ipv6-regexp "\\)"
-	   "\\(?:" tramp-prefix-port-regexp  tramp-port-regexp "\\)?" "\\)?"))
+  (rx ;; Method.
+      (group (regexp tramp-method-regexp)) (regexp tramp-postfix-method-regexp)
+      ;; Optional user.
+      (? (group (regexp tramp-user-regexp)) (regexp tramp-postfix-user-regexp))
+      ;; Optional host.
+      (? (group (| (regexp tramp-host-regexp)
+                   (: (regexp tramp-prefix-ipv6-regexp)
+		      (? (regexp tramp-ipv6-regexp))
+		      (regexp tramp-postfix-ipv6-regexp)))
+      ;; Optional port.
+      (? (regexp tramp-prefix-port-regexp) (regexp tramp-port-regexp))))))
 
 (defvar tramp-remote-file-name-spec-regexp
-   nil ;Initialized when defining `tramp-syntax'!
+  nil ; Initialized when defining `tramp-syntax'!
   "Regular expression matching a Tramp file name between prefix and postfix.")
 
 (defun tramp-build-file-name-structure ()
@@ -1084,15 +1100,15 @@ It is expected, that `tramp-syntax' has the proper value."
 It is expected, that `tramp-syntax' has the proper value.
 See `tramp-file-name-structure'."
   (list
-   (concat
-    tramp-prefix-regexp
-    "\\(" "\\(?:" tramp-remote-file-name-spec-regexp
-                  tramp-postfix-hop-regexp "\\)+" "\\)?"
-    tramp-remote-file-name-spec-regexp tramp-postfix-host-regexp
-    "\\(" tramp-localname-regexp "\\)")
+   (rx (regexp tramp-prefix-regexp)
+       (? (group (+ (regexp tramp-remote-file-name-spec-regexp)
+		    (regexp tramp-postfix-hop-regexp))))
+       (regexp tramp-remote-file-name-spec-regexp)
+       (regexp tramp-postfix-host-regexp)
+       (group (regexp tramp-localname-regexp)))
    5 6 7 8 1))
 
-(defvar tramp-file-name-structure nil ;Initialized when defining `tramp-syntax'!
+(defvar tramp-file-name-structure nil ; Initialized when defining `tramp-syntax'!
   "List detailing the Tramp file name structure.
 This is a list of six elements (REGEXP METHOD USER HOST FILE HOP).
 
@@ -1117,7 +1133,8 @@ See also `tramp-file-name-regexp'.")
   (car tramp-file-name-structure))
 
 ;;;###autoload
-(defconst tramp-initial-file-name-regexp "\\`/[^/:]+:[^/:]*:"
+(defconst tramp-initial-file-name-regexp
+  (rx bos "/" (+ (not (any "/:"))) ":" (* (not (any "/:"))) ":")
   "Value for `tramp-file-name-regexp' for autoload.
 It must match the initial `tramp-syntax' settings.")
 
@@ -1134,78 +1151,56 @@ initial value is overwritten by the car of `tramp-file-name-structure'.")
   :version "27.1"
   :type '(choice (const nil) regexp))
 
-(defconst tramp-completion-file-name-regexp-default
-  (concat
-   "\\`"
-   ;; `file-name-completion' uses absolute paths for matching.  This
-   ;; means that on W32 systems, something like "/ssh:host:~/path"
-   ;; becomes "c:/ssh:host:~/path".  See also `tramp-drop-volume-letter'.
-   (when (eq system-type 'windows-nt)
-       "\\(?:[[:alpha:]]:\\)?")
-   "/\\("
-   ;; Optional multi hop.
-   "\\([^/|:]+:[^/|:]*|\\)*"
-   ;; Last hop.
-   (if (memq system-type '(cygwin windows-nt))
-       ;; The method is either "-", or at least two characters.
-       "\\(-\\|[^/|:]\\{2,\\}\\)"
-     ;; At least one character for method.
-     "[^/|:]+")
-   ;; Method separator, user name and host name.
-   "\\(:[^/|:]*\\)?"
-   "\\)?\\'")
-  "Value for `tramp-completion-file-name-regexp' for default remoting.
-See `tramp-file-name-structure' for more explanations.
-
-On W32 systems, the volume letter must be ignored.")
-
-(defconst tramp-completion-file-name-regexp-simplified
-  (concat
-   "\\`"
-   ;; Allow the volume letter at the beginning of the path.  See the
-   ;; comment in `tramp-completion-file-name-regexp-default' for more
-   ;; details.
-   (when (eq system-type 'windows-nt)
-     "\\(?:[[:alpha:]]:\\)?")
-   "/\\("
-   ;; Optional multi hop.
-   "\\([^/|:]*|\\)*"
-   ;; Last hop.
-   (if (memq system-type '(cygwin windows-nt))
-       ;; At least two characters.
-       "[^/|:]\\{2,\\}"
-     ;; At least one character.
-     "[^/|:]+")
-   "\\)?\\'")
-  "Value for `tramp-completion-file-name-regexp' for simplified style remoting.
-See `tramp-file-name-structure' for more explanations.
-
-On W32 systems, the volume letter must be ignored.")
-
-(defconst tramp-completion-file-name-regexp-separate
-  (concat
-   "\\`"
-   ;; Allow the volume letter at the beginning of the path.  See the
-   ;; comment in `tramp-completion-file-name-regexp-default' for more
-   ;; details.
-   (when (eq system-type 'windows-nt)
-     "\\(?:[[:alpha:]]:\\)?")
-   "/\\(\\[[^]]*\\)?\\'")
-  "Value for `tramp-completion-file-name-regexp' for separate remoting.
-See `tramp-file-name-structure' for more explanations.")
-
-(defconst tramp-completion-file-name-regexp-alist
-  `((default    . ,tramp-completion-file-name-regexp-default)
-    (simplified . ,tramp-completion-file-name-regexp-simplified)
-    (separate   . ,tramp-completion-file-name-regexp-separate))
-  "Alist mapping incomplete Tramp file names.")
+(defconst tramp-volume-letter-regexp
+  (if (eq system-type 'windows-nt)
+      (rx bos alpha ":") "")
+  "Volume letter on MS Windows.")
+
+;; `tramp-method-regexp' needs at least two characters, in order to
+;; distinguish from volume letter.  This is in the way when completing.
+(defconst tramp-completion-method-regexp-alist
+  `((default    . ,(rx (| (literal tramp-default-method-marker) (+ alnum))))
+    (simplified . "")
+    (separate   . ,(rx (| (literal tramp-default-method-marker) (* alnum)))))
+  "Alist mapping Tramp syntax to regexps matching completion methods.")
+
+(defun tramp-build-completion-method-regexp ()
+  "Return `tramp-completion-method-regexp' according to `tramp-syntax'."
+  (tramp-lookup-syntax tramp-completion-method-regexp-alist))
+
+(defvar tramp-completion-method-regexp
+  nil ; Initialized when defining `tramp-syntax'!
+  "Regexp matching completion method identifiers.
+The `ftp' syntax does not support methods.")
 
 (defun tramp-build-completion-file-name-regexp ()
   "Return `tramp-completion-file-name-regexp' according to `tramp-syntax'."
-  (tramp-lookup-syntax tramp-completion-file-name-regexp-alist))
+  (if (eq tramp-syntax 'separate)
+      ;; FIXME: This shouldn't be necessary.
+      (rx bos "/" (? (group "[" (* (not (any "]"))))) eos)
+  (rx bos
+      ;; `file-name-completion' uses absolute paths for matching.
+      ;; This means that on W32 systems, something like
+      ;; "/ssh:host:~/path" becomes "c:/ssh:host:~/path".  See also
+      ;; `tramp-drop-volume-letter'.
+      (? (regexp tramp-volume-letter-regexp))
+      (regexp tramp-prefix-regexp)
+
+      ;; Optional multi hops.
+      (* (regexp tramp-remote-file-name-spec-regexp)
+         (regexp tramp-postfix-hop-regexp))
+
+      ;; Last hop.
+      (? (regexp tramp-completion-method-regexp)
+	 ;; Method separator, user name and host name.
+	 (? (regexp tramp-postfix-method-regexp)
+	    ;; This is a little bit lax, but it serves.
+	    (? (regexp tramp-host-regexp))))
+
+      eos)))
 
 (defvar tramp-completion-file-name-regexp
-   nil ;Initialized when defining `tramp-syntax'!
+   nil ; Initialized when defining `tramp-syntax'!
   "Regular expression matching file names handled by Tramp completion.
 This regexp should match partial Tramp file names only.
 
@@ -1218,14 +1213,8 @@ Also see `tramp-file-name-structure'.")
 
 ;;;###autoload
 (defconst tramp-autoload-file-name-regexp
-  (concat
-   "\\`/"
-   (if (memq system-type '(cygwin windows-nt))
-       ;; The method is either "-", or at least two characters.
-       "\\(-\\|[^/|:]\\{2,\\}\\)"
-     ;; At least one character for method.
-     "[^/|:]+")
-   ":")
+  ;; The method is either "-", or at least two characters.
+  (rx bos "/" (| "-" (>= 2 (not (any "/:|")))) ":")
   "Regular expression matching file names handled by Tramp autoload.
 It must match the initial `tramp-syntax' settings.  It should not
 match file names at root of the underlying local file system,
@@ -1528,7 +1517,7 @@ If VEC is a vector, check first in connection properties.
 Afterwards, check in `tramp-methods'.  If the `tramp-methods'
 entry does not exist, return nil."
   (let ((hash-entry
-	 (replace-regexp-in-string "^tramp-" "" (symbol-name param))))
+	 (replace-regexp-in-string (rx bos "tramp-") "" (symbol-name param))))
     (if (tramp-connection-property-p vec hash-entry)
 	;; We use the cached property.
 	(tramp-get-connection-property vec hash-entry)
@@ -1548,10 +1537,7 @@ entry does not exist, return nil."
   "Return t if NAME is a string with Tramp file name syntax."
   (and tramp-mode (stringp name)
        ;; No "/:" and "/c:".  This is not covered by `tramp-file-name-regexp'.
-       (not (string-match-p
-	     (if (memq system-type '(cygwin windows-nt))
-		 "^/[[:alpha:]]?:" "^/:")
-	     name))
+       (not (string-match-p (rx bos "/" (? alpha) ":") name))
        ;; Excluded file names.
        (or (null tramp-ignored-file-name-regexp)
 	   (not (string-match-p tramp-ignored-file-name-regexp name)))
@@ -1744,7 +1730,7 @@ See `tramp-dissect-file-name' for details."
   (let ((v (tramp-dissect-file-name
 	    (concat tramp-prefix-format
 		    (replace-regexp-in-string
-		     (concat tramp-postfix-hop-regexp "$")
+		     (rx (regexp tramp-postfix-hop-regexp) eos)
 		     tramp-postfix-host-format name))
 	    nodefault)))
     ;; Only some methods from tramp-sh.el do support multi-hops.
@@ -1797,7 +1783,7 @@ the form (METHOD USER DOMAIN HOST PORT LOCALNAME &optional HOP)."
 	;; Assure that the hops are in `tramp-default-proxies-alist'.
 	;; In tramp-archive.el, the slot `hop' is used for the archive
 	;; file name.
-	(unless (string-equal method "archive")
+	(unless (string-equal method tramp-archive-method)
 	  (tramp-add-hops (car args)))))
 
      (t (setq method (nth 0 args)
@@ -1840,7 +1826,7 @@ the form (METHOD USER DOMAIN HOST PORT LOCALNAME &optional HOP)."
    (replace-regexp-in-string
     tramp-prefix-regexp ""
     (replace-regexp-in-string
-     (concat tramp-postfix-host-regexp "$") tramp-postfix-hop-format
+     (rx (regexp tramp-postfix-host-regexp) eos) tramp-postfix-hop-format
      (tramp-make-tramp-file-name vec 'noloc)))))
 
 (defun tramp-completion-make-tramp-file-name (method user host localname)
@@ -1955,10 +1941,12 @@ of `current-buffer'."
 (put #'tramp-debug-buffer-name 'tramp-suppress-trace t)
 
 (defconst tramp-debug-outline-regexp
-  (concat
-   "[[:digit:]]+:[[:digit:]]+:[[:digit:]]+\\.[[:digit:]]+ " ;; Timestamp.
-   "\\(?:\\(#<thread .+>\\) \\)?" ;; Thread.
-   "[[:alnum:]-]+ (\\([[:digit:]]+\\)) #") ;; Function name, verbosity.
+  (rx ;; Timestamp.
+      (+ digit) ":" (+ digit) ":" (+ digit) "." (+ digit) " "
+      ;; Thread.
+      (? (group "#<thread " (+ nonl) ">") " ")
+       ;; Function name, verbosity.
+      (+ (any "-" alnum)) " (" (group (group (+ digit))) ") #")
   "Used for highlighting Tramp debug buffers in `outline-mode'.")
 
 (defconst tramp-debug-font-lock-keywords
@@ -1967,7 +1955,7 @@ of `current-buffer'."
   ;; Also, in `font-lock-defaults' you can specify a function name for
   ;; the "KEYWORDS" part, so font-lock calls it to get the actual keywords!
   '(list
-    (concat "^\\(?:" tramp-debug-outline-regexp "\\).+")
+    (rx bol (regexp tramp-debug-outline-regexp) (+ nonl))
     '(1 font-lock-warning-face t t)
     '(0 (outline-font-lock-face) keep t))
   "Used for highlighting Tramp debug buffers in `outline-mode'.")
@@ -2421,13 +2409,16 @@ letter into the file name.  This function removes it."
   (save-match-data
     (let ((quoted (tramp-compat-file-name-quoted-p name 'top))
 	  (result (tramp-compat-file-name-unquote name 'top)))
-      (setq result (if (string-match "\\`[[:alpha:]]:/" result)
-		     (replace-match "/" nil t result) result))
+      (setq result
+	    (if (string-match
+		 (rx (regexp tramp-volume-letter-regexp) "/") result)
+		(replace-match "/" nil t result) result))
       (if quoted (tramp-compat-file-name-quote result 'top) result))))
 
 ;;; Config Manipulation Functions:
 
-(defconst tramp-dns-sd-service-regexp "^_[-[:alnum:]]+\\._tcp$"
+(defconst tramp-dns-sd-service-regexp
+  (rx bol "_" (+ (any "-" alnum)) "._tcp" eol)
   "DNS-SD service regexp.")
 
 ;;;###tramp-autoload
@@ -2530,7 +2521,7 @@ coding system might not be determined.  This function repairs it."
 	;; We found a matching entry in `file-coding-system-alist'.
 	;; So we add a similar entry, but with the temporary file name
 	;; as regexp.
-	(push (cons (regexp-quote tmpname) (cdr elt)) result)))))
+	(push (cons (rx (literal tmpname)) (cdr elt)) result)))))
 
 (defun tramp-run-real-handler (operation args)
   "Invoke normal file name handler for OPERATION.
@@ -2808,14 +2799,12 @@ This avoids problems during autoload, when `load-path' contains
 remote file names."
   ;; We expect all other Tramp files in the same directory as tramp.el.
   (let* ((dir (expand-file-name (file-name-directory (locate-library "tramp"))))
-	 (files-regexp
-	  (format
-	   "^%s$"
-	   (regexp-opt
-	    (mapcar
-	     #'file-name-sans-extension
-	     (directory-files dir nil "\\`tramp.+\\.elc?\\'"))
-	    'paren))))
+	 (files (delete-dups
+		 (mapcar
+		  #'file-name-sans-extension
+		  (directory-files
+		   dir nil (rx bos "tramp" (+ nonl) ".el" (? "c") eos)))))
+	 (files-regexp (rx bol (: (regexp (regexp-opt files))) eol)))
     (mapatoms
      (lambda (atom)
        (when (and (functionp atom)
@@ -2960,11 +2949,9 @@ not in completion mode."
 
     ;; Suppress hop from completion.
     (when (string-match
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" "\\(" tramp-remote-file-name-spec-regexp
-	                tramp-postfix-hop-regexp
-	    "\\)+" "\\)")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (+ (regexp tramp-remote-file-name-spec-regexp)
+			 (regexp tramp-postfix-hop-regexp))))
 	   fullname)
       (setq hop (match-string 1 fullname)
 	    fullname (replace-match "" nil nil fullname 1)))
@@ -3046,68 +3033,62 @@ not in completion mode."
 ;; ["x" nil "" nil]     ["x" nil "y" nil]    ["x" nil "y" ""]
 ;; ["x" "" nil nil]     ["x" "y" nil nil]
 
-;; "/x:y@""/[x/y@"      "/x:y@z" "/[x/y@z"   "/x:y@z:" "/[x/y@z]"
-;;["x" "y" nil nil]     ["x" "y" "z" nil]    ["x" "y" "z" ""]
+;; "/x:y@" "/[x/y@"     "/x:y@z" "/[x/y@z"   "/x:y@z:" "/[x/y@z]"
+;; ["x" "y" nil nil]    ["x" "y" "z" nil]    ["x" "y" "z" ""]
 (defun tramp-completion-dissect-file-name (name)
   "Return a list of `tramp-file-name' structures for NAME.
 They are collected by `tramp-completion-dissect-file-name1'."
-  (let* ((x-nil "\\|\\(\\)")
-	 (tramp-completion-ipv6-regexp
-	  (format
-	   "[^%s]*"
-	   (if (zerop (length tramp-postfix-ipv6-format))
-	       tramp-postfix-host-format
-	     tramp-postfix-ipv6-format)))
-	 ;; "/method" "/[method"
+  (let* (;; "/method" "/[method"
 	 (tramp-completion-file-name-structure1
 	  (list
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" tramp-method-regexp x-nil "\\)$")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (? (regexp tramp-completion-method-regexp))) eol)
 	   1 nil nil nil))
 	 ;; "/method:user" "/[method/user"
 	 (tramp-completion-file-name-structure2
 	  (list
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
-	    "\\(" tramp-user-regexp x-nil   "\\)$")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (regexp tramp-method-regexp))
+	       (regexp tramp-postfix-method-regexp)
+	       (group (? (regexp tramp-user-regexp))) eol)
 	   1 2 nil nil))
 	 ;; "/method:host" "/[method/host"
 	 (tramp-completion-file-name-structure3
 	  (list
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
-	    "\\(" tramp-host-regexp x-nil   "\\)$")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (regexp tramp-method-regexp))
+	       (regexp tramp-postfix-method-regexp)
+	       (group (? (regexp tramp-host-regexp))) eol)
 	   1 nil 2 nil))
 	 ;; "/method:[ipv6" "/[method/ipv6"
 	 (tramp-completion-file-name-structure4
 	  (list
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
-	    tramp-prefix-ipv6-regexp
-	    "\\(" tramp-completion-ipv6-regexp x-nil "\\)$")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (regexp tramp-method-regexp))
+	       (regexp tramp-postfix-method-regexp)
+	       (regexp tramp-prefix-ipv6-regexp)
+	       (group (? (regexp tramp-ipv6-regexp))) eol)
 	   1 nil 2 nil))
 	 ;; "/method:user@host" "/[method/user@host"
 	 (tramp-completion-file-name-structure5
 	  (list
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
-	    "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp
-	    "\\(" tramp-host-regexp x-nil   "\\)$")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (regexp tramp-method-regexp))
+	       (regexp tramp-postfix-method-regexp)
+	       (group (regexp tramp-user-regexp))
+	       (regexp tramp-postfix-user-regexp)
+	       (group (? (regexp tramp-host-regexp))) eol)
 	   1 2 3 nil))
 	 ;; "/method:user@[ipv6" "/[method/user@ipv6"
 	 (tramp-completion-file-name-structure6
 	  (list
-	   (concat
-	    tramp-prefix-regexp
-	    "\\(" tramp-method-regexp "\\)" tramp-postfix-method-regexp
-	    "\\(" tramp-user-regexp "\\)"   tramp-postfix-user-regexp
-	    tramp-prefix-ipv6-regexp
-	    "\\(" tramp-completion-ipv6-regexp x-nil "\\)$")
+	   (rx (regexp tramp-prefix-regexp)
+	       (group (regexp tramp-method-regexp))
+	       (regexp tramp-postfix-method-regexp)
+	       (group (regexp tramp-user-regexp))
+	       (regexp tramp-postfix-user-regexp)
+	       (regexp tramp-prefix-ipv6-regexp)
+	       (group (? (regexp tramp-ipv6-regexp))) eol)
 	   1 2 3 nil)))
     (delq
      nil
@@ -3233,11 +3214,10 @@ Either user or host may be nil."
 Either user or host may be nil."
    (let (result
 	 (regexp
-	  (concat
-	   "^\\(" tramp-host-regexp "\\)"
-	   "\\([ \t]+" "\\(" tramp-user-regexp "\\)" "\\)?")))
+	  (rx bol (group (regexp tramp-host-regexp))
+	      (? (+ space) (group (regexp tramp-user-regexp))))))
      (when (re-search-forward regexp (line-end-position) t)
-       (setq result (append (list (match-string 3) (match-string 1)))))
+       (setq result (append (list (match-string 2) (match-string 1)))))
      (forward-line 1)
      result))
 
@@ -3249,7 +3229,7 @@ User is always nil."
 (defun tramp-parse-shosts-group ()
    "Return a (user host) tuple allowed to access.
 User is always nil."
-   (tramp-parse-group (concat "^\\(" tramp-host-regexp "\\)") 1 ","))
+   (tramp-parse-group (rx bol (group (regexp tramp-host-regexp))) 1 ","))
 
 (defun tramp-parse-sconfig (filename)
   "Return a list of (user host) tuples allowed to access.
@@ -3260,9 +3240,10 @@ User is always nil."
    "Return a (user host) tuple allowed to access.
 User is always nil."
    (tramp-parse-group
-    (concat "\\(?:^[ \t]*Host\\)" "\\|" "\\(?:^.+\\)"
-	    "\\|" "\\(" tramp-host-regexp "\\)")
-    1 " \t"))
+    (rx (| (: bol (* space) "Host")
+	   (: bol (+ nonl)) ;; ???
+	   (group (regexp tramp-host-regexp))))
+    1 (rx space)))
 
 ;; Generic function.
 (defun tramp-parse-shostkeys-sknownhosts (dirname regexp)
@@ -3274,21 +3255,24 @@ User is always nil."
 	 (files (and (file-directory-p dirname) (directory-files dirname))))
     (cl-loop
      for f in files
-     when (and (not (string-match "^\\.\\.?$" f)) (string-match regexp f))
+     when (and (not (string-match-p (rx bol (** 1 2 ".") eol) f))
+	       (string-match regexp f))
      collect (list nil (match-string 1 f)))))
 
 (defun tramp-parse-shostkeys (dirname)
   "Return a list of (user host) tuples allowed to access.
 User is always nil."
   (tramp-parse-shostkeys-sknownhosts
-   dirname (concat "^key_[[:digit:]]+_\\(" tramp-host-regexp "\\)\\.pub$")))
+   dirname
+   (rx bol "key_" (+ digit) "_" (group (regexp tramp-host-regexp)) ".pub" eol)))
 
 (defun tramp-parse-sknownhosts (dirname)
   "Return a list of (user host) tuples allowed to access.
 User is always nil."
   (tramp-parse-shostkeys-sknownhosts
    dirname
-   (concat "^\\(" tramp-host-regexp "\\)\\.ssh-\\(dss\\|rsa\\)\\.pub$")))
+   (rx bol (group (regexp tramp-host-regexp))
+       ".ssh-" (| "dss" "rsa") ".pub" eol)))
 
 (defun tramp-parse-hosts (filename)
   "Return a list of (user host) tuples allowed to access.
@@ -3299,7 +3283,8 @@ User is always nil."
    "Return a (user host) tuple allowed to access.
 User is always nil."
    (tramp-parse-group
-    (concat "^\\(" tramp-ipv6-regexp "\\|" tramp-host-regexp "\\)") 1 " \t"))
+    (rx bol (group (| (regexp tramp-ipv6-regexp) (regexp tramp-host-regexp))))
+    1 (rx space)))
 
 (defun tramp-parse-passwd (filename)
   "Return a list of (user host) tuples allowed to access.
@@ -3317,7 +3302,7 @@ Host is always \"localhost\"."
    "Return a (user host) tuple allowed to access.
 Host is always \"localhost\"."
    (let (result
-	 (regexp (concat "^\\(" tramp-user-regexp "\\):")))
+	 (regexp (rx bol (group (regexp tramp-user-regexp)) ":")))
      (when (re-search-forward regexp (line-end-position) t)
        (setq result (list (match-string 1) "localhost")))
      (forward-line 1)
@@ -3339,7 +3324,8 @@ Host is always \"localhost\"."
    "Return a (group host) tuple allowed to access.
 Host is always \"localhost\"."
    (let (result
-         (split (split-string (buffer-substring (point) (line-end-position)) ":")))
+	 (split
+	  (split-string (buffer-substring (point) (line-end-position)) ":")))
      (when (member (user-login-name) (split-string (nth 3 split) "," 'omit))
        (setq result (list (nth 0 split) "localhost")))
      (forward-line 1)
@@ -3367,13 +3353,13 @@ User is always nil."
 		     (tramp-parse-putty-group registry-or-dirname)))))
     ;; UNIX case.
     (tramp-parse-shostkeys-sknownhosts
-     registry-or-dirname (concat "^\\(" tramp-host-regexp "\\)$"))))
+     registry-or-dirname (rx bol (group (regexp tramp-host-regexp)) eol))))
 
 (defun tramp-parse-putty-group (registry)
    "Return a (user host) tuple allowed to access.
 User is always nil."
    (let (result
-	 (regexp (concat (regexp-quote registry) "\\\\\\(.+\\)")))
+	 (regexp (rx (literal registry) "\\" (group (+ nonl)))))
      (when (re-search-forward regexp (line-end-position) t)
        (setq result (list nil (match-string 1))))
      (forward-line 1)
@@ -3773,7 +3759,9 @@ Let-bind it when necessary.")
       ;; Expand tilde.  Usually, the methods applying this handler do
       ;; not support tilde expansion.  But users could declare a
       ;; respective connection property.  (Bug#53847)
-      (when (string-match "\\`~\\([^/]*\\)\\(.*\\)\\'" localname)
+      (when (string-match
+	     (rx bos "~" (group (* (not (any "/")))) (group (* nonl)) eos)
+	     localname)
 	(let ((uname (match-string 1 localname))
 	      (fname (match-string 2 localname))
 	      hname)
@@ -3783,10 +3771,10 @@ Let-bind it when necessary.")
 	    (setq localname (concat hname fname)))))
       ;; Tilde expansion is not possible.
       (when (and (not tramp-tolerate-tilde)
-		 (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname))
+		 (string-prefix-p "~" localname))
 	(tramp-error v 'file-error "Cannot expand tilde in file `%s'" name))
       ;; Do not keep "/..".
-      (when (string-match-p "^/\\.\\.?$" localname)
+      (when (string-match-p (rx bos "/" (** 1 2 ".") eos) localname)
 	(setq localname "/"))
       ;; Do normal `expand-file-name' (this does "/./" and "/../").
       ;; `default-directory' is bound, because on Windows there would
@@ -3794,7 +3782,7 @@ Let-bind it when necessary.")
       (let ((default-directory tramp-compat-temporary-file-directory))
 	(tramp-make-tramp-file-name
 	 v (tramp-drop-volume-letter
-	    (if (string-match-p "\\`\\(~[^/]*\\)\\(.*\\)\\'" localname)
+	    (if (string-prefix-p "~" localname)
 		localname
 	      (tramp-run-real-handler #'expand-file-name (list localname)))))))))
 
@@ -3805,7 +3793,10 @@ Let-bind it when necessary.")
 
 (defun tramp-handle-file-directory-p (filename)
   "Like `file-directory-p' for Tramp files."
-  (eq (file-attribute-type (file-attributes (file-truename filename))) t))
+  ;; `file-truename' could raise an error, for example due to a cyclic
+  ;; symlink.
+  (ignore-errors
+    (eq (file-attribute-type (file-attributes (file-truename filename))) t)))
 
 (defun tramp-handle-file-equal-p (filename1 filename2)
   "Like `file-equalp-p' for Tramp files."
@@ -3890,7 +3881,7 @@ Let-bind it when necessary.")
 		  ;; lower case letters.  This avoids us to create a
 		  ;; temporary file.
 		  (while (and (string-match-p
-			       "[[:lower:]]" (tramp-file-local-name candidate))
+			       (rx lower) (tramp-file-local-name candidate))
 			      (not (file-exists-p candidate)))
 		    (setq candidate
 			  (directory-file-name
@@ -3898,7 +3889,7 @@ Let-bind it when necessary.")
 		  ;; Nothing found, so we must use a temporary file
 		  ;; for comparison.
 		  (unless (string-match-p
-			   "[[:lower:]]" (tramp-file-local-name candidate))
+			   (rx lower) (tramp-file-local-name candidate))
 		    (setq tmpfile
 			  (let ((default-directory
 				 (file-name-directory filename)))
@@ -3933,7 +3924,8 @@ Let-bind it when necessary.")
 	   (and
 	    completion-ignored-extensions
 	    (string-match-p
-	     (concat (regexp-opt completion-ignored-extensions 'paren) "$") x)
+	     (rx (regexp (regexp-opt completion-ignored-extensions)) eos)
+	     x)
 	    ;; We remember the hit.
 	    (push x hits-ignored-extensions))))))
      ;; No match.  So we try again for ignored files.
@@ -3975,7 +3967,8 @@ Let-bind it when necessary.")
 	  ;; links.
 	  (when-let ((symlink (file-symlink-p filename)))
 	    (and (stringp symlink)
-		 (file-readable-p (concat (file-remote-p filename) symlink))))))))
+		 (file-readable-p
+		  (concat (file-remote-p filename) symlink))))))))
 
 (defun tramp-handle-file-regular-p (filename)
   "Like `file-regular-p' for Tramp files."
@@ -4111,9 +4104,10 @@ Let-bind it when necessary.")
 		   (not (with-tramp-connection-property
 			    (tramp-get-process v) "unsafe-temporary-file"
 			  (yes-or-no-p
-			   (concat
-			    "Backup file on local temporary directory, "
-			    "do you want to continue?")))))
+			   (eval-when-compile
+			     (concat
+			      "Backup file on local temporary directory, "
+			      "do you want to continue?"))))))
 	  (tramp-error v 'file-error "Unsafe backup file name"))))))
 
 (defun tramp-handle-insert-directory
@@ -4142,12 +4136,13 @@ Let-bind it when necessary.")
 	    (goto-char (point-min))
 	    (while (setq start
 			 (text-property-not-all
-                          (point) (line-end-position) 'dired-filename t))
+			  (point) (line-end-position) 'dired-filename t))
 	      (delete-region
 	       start
-               (or (text-property-any start (line-end-position) 'dired-filename t)
-                   (line-end-position)))
-              (if (= (line-beginning-position) (line-end-position))
+	       (or (text-property-any
+		    start (line-end-position) 'dired-filename t)
+		   (line-end-position)))
+	      (if (= (line-beginning-position) (line-end-position))
 		  ;; Empty line.
 		  (delete-region (point) (progn (forward-line) (point)))
 		(forward-line)))))))))
@@ -4269,15 +4264,13 @@ Let-bind it when necessary.")
 (defun tramp-ps-time ()
   "Read printed time oif \"ps\" in format \"[[DD-]hh:]mm:ss\".
 Return it as number of seconds.  Used in `tramp-process-attributes-ps-format'."
-  (search-forward-regexp "\\s-+")
-  (search-forward-regexp
-   (concat
-    "\\(?:" "\\(?:" "\\([0-9]+\\)-" "\\)?"
-                    "\\([0-9]+\\):" "\\)?"
-                    "\\([0-9]+\\):"
-                    ;; Seconds can also be a floating point number.
-                    "\\([0-9.]+\\)")
-   (line-end-position) 'noerror)
+  (search-forward-regexp (rx (+ space)))
+  (search-forward-regexp (rx (? (? (group (+ digit)) "-")
+				   (group (+ digit)) ":")
+			           (group (+ digit)) ":"
+			           ;; Seconds can also be a floating point num.
+			           (group (+ (any "." digit))))
+			 (line-end-position) 'noerror)
   (+ (* 24 60 60 (string-to-number (or (match-string 1) "0")))
         (* 60 60 (string-to-number (or (match-string 2) "0")))
            (* 60 (string-to-number (or (match-string 3) "0")))
@@ -4382,7 +4375,7 @@ It is not guaranteed, that all process attributes as described in
                 ;;  "%s" (buffer-substring (point) (line-end-position)))
                 (when (save-excursion
                         (search-forward-regexp
-                         "[[:digit:]]" (line-end-position) 'noerror))
+			 (rx digit) (line-end-position) 'noerror))
                   (setq res nil)
                   (dolist (elt tramp-process-attributes-ps-format)
                     (push
@@ -4391,16 +4384,17 @@ It is not guaranteed, that all process attributes as described in
                       (cond
                        ((eq (cdr elt) 'number) (read (current-buffer)))
                        ((eq (cdr elt) 'string)
-                        (search-forward-regexp "\\S-+")
+                        (search-forward-regexp (rx (+ (not space))))
                         (match-string 0))
                        ((numberp (cdr elt))
-                        (search-forward-regexp "\\s-+")
-                        (search-forward-regexp ".+" (+ (point) (cdr elt)))
+                        (search-forward-regexp (rx (+ space)))
+                        (search-forward-regexp
+			 (rx (+ nonl)) (+ (point) (cdr elt)))
                         (string-trim (match-string 0)))
                        ((fboundp (cdr elt))
                         (funcall (cdr elt)))
                        ((null (cdr elt))
-                        (search-forward-regexp "\\s-+")
+                        (search-forward-regexp (rx (+ whitespace)))
                         (buffer-substring (point) (line-end-position)))))
                      res))
                   ;; `nice' could be `-'.
@@ -4442,7 +4436,10 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
 
 (defconst tramp-lock-file-info-regexp
   ;; USER@HOST.PID[:BOOT_TIME]
-  "\\`\\(.+\\)@\\(.+\\)\\.\\([[:digit:]]+\\)\\(?::\\([[:digit:]]+\\)\\)?\\'"
+  (rx bos (group (+ nonl))
+      "@" (group (+ nonl))
+      "." (group (+ digit))
+      (? ":" (group (+ digit))) eos)
   "The format of a lock file.")
 
 (defun tramp-handle-file-locked-p (file)
@@ -4497,9 +4494,10 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
 		     (not (with-tramp-connection-property
 			      (tramp-get-process v) "unsafe-temporary-file"
 			    (yes-or-no-p
-			     (concat
-			      "Lock file on local temporary directory, "
-			      "do you want to continue?")))))
+			     (eval-when-compile
+			       (concat
+				"Lock file on local temporary directory, "
+				"do you want to continue?"))))))
 	    (tramp-error v 'file-error "Unsafe lock file name")))
 
 	;; Do the lock.
@@ -4538,7 +4536,7 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
       ;; The first condition is always true for absolute file names.
       ;; Included for safety's sake.
       (unless (or (file-name-directory file)
-		  (string-match-p "\\.elc?\\'" file))
+		  (string-match-p (rx ".el" (? "c") eos) file))
 	(tramp-error
 	 v 'file-error
 	 "File `%s' does not include a `.el' or `.elc' suffix" file)))
@@ -4571,9 +4569,9 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
 		     tramp-prefix-format proxy tramp-postfix-host-format))
 	     (entry
 	      (list (and (stringp host-port)
-			 (concat "^" (regexp-quote host-port) "$"))
+			 (rx bol (literal host-port) eol))
 		    (and (stringp user-domain)
-			 (concat "^" (regexp-quote user-domain) "$"))
+			 (rx bol (literal user-domain) eol))
 		    (propertize proxy 'tramp-ad-hoc t))))
 	(tramp-message vec 5 "Add %S to `tramp-default-proxies-alist'" entry)
 	;; Add the hop.
@@ -4652,7 +4650,7 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
 	    (setq tramp-default-proxies-alist saved-tdpa)
 	    (tramp-user-error
 	     vec "Host name `%s' does not match `%s'" host previous-host))
-	  (setq previous-host (concat "^" (regexp-quote host) "$")))))
+	  (setq previous-host (rx bol (literal host) eol)))))
 
     ;; Result.
     target-alist))
@@ -4841,7 +4839,7 @@ support symbolic links."
 
 (defun tramp-handle-shell-command (command &optional output-buffer error-buffer)
   "Like `shell-command' for Tramp files."
-  (let* ((asynchronous (string-match-p "[ \t]*&[ \t]*\\'" command))
+  (let* ((asynchronous (string-match-p (rx (* space) "&" (* space) eos) command))
 	 (command (substring command 0 asynchronous))
 	 current-buffer-p
 	 (output-buffer-p output-buffer)
@@ -5024,14 +5022,14 @@ BUFFER might be a list, in this case STDERR is separated."
       (let (process-environment)
 	;; Ignore in LOCALNAME everything before "//" or "/~".
 	(when (stringp localname)
-	  (if (string-match "//\\(/\\|~\\)" localname)
+	  (if (string-match-p (rx "//" (| "/" "~")) localname)
 	      (setq filename
                     (replace-regexp-in-string
-                     "\\`/+" "/" (substitute-in-file-name localname)))
+                     (rx bos (+ "/")) "/" (substitute-in-file-name localname)))
 	    (setq filename
 		  (concat (file-remote-p filename)
 			  (replace-regexp-in-string
-                           "\\`/+" "/"
+                           (rx bos (+ "/")) "/"
 			   ;; We must disable cygwin-mount file name
 			   ;; handlers and alike.
 			   (tramp-run-real-handler
@@ -5278,7 +5276,8 @@ Wait, until the connection buffer changes."
       (ignore set-message-function clear-message-function)
       (tramp-message vec 6 "\n%s" (buffer-string))
       (tramp-check-for-regexp proc tramp-process-action-regexp)
-      (with-temp-message (replace-regexp-in-string "[\r\n]" "" (match-string 0))
+      (with-temp-message
+	  (replace-regexp-in-string (rx (any "\r\n")) "" (match-string 0))
 	;; Hide message in buffer.
 	(narrow-to-region (point-max) (point-max))
 	;; Wait for new output.
@@ -5614,7 +5613,7 @@ the remote host use line-endings as defined in the variable
         (tramp-flush-directory-properties vec "/"))
       (when (buffer-live-p buf)
 	(with-current-buffer buf
-          (when (and prompt (tramp-search-regexp (regexp-quote prompt)))
+          (when (and prompt (tramp-search-regexp (rx (literal prompt))))
 	    (delete-region (point) (point-max))))))))
 
 (defun tramp-get-inode (vec)
@@ -5818,7 +5817,7 @@ VEC is used for tracing."
 	  (while candidates
 	    (goto-char (point-min))
 	    (if (string-match-p
-		 (format "^%s\r?$" (regexp-quote (car candidates)))
+		 (rx bol (literal (car candidates)) (? "\r") eol)
 		 (buffer-string))
 		(setq locale (car candidates)
 		      candidates nil)
@@ -5926,7 +5925,9 @@ to cache the result.  Return the modified ATTR."
 		 (when (consp (car attr))
 		   (setcar attr
 			   (and (stringp (caar attr))
-				(string-match ".+ -> .\\(.+\\)." (caar attr))
+				(string-match
+				 (rx (+ nonl) " -> " nonl (group (+ nonl)) nonl)
+				 (caar attr))
 				(decode-coding-string
 				 (match-string 1 (caar attr)) 'utf-8))))
 		 ;; Set file's gid change bit.
@@ -6111,9 +6112,10 @@ this file, if that variable is non-nil."
 		   (not (with-tramp-connection-property
 			    (tramp-get-process v) "unsafe-temporary-file"
 			  (yes-or-no-p
-			   (concat
-			    "Autosave file on local temporary directory, "
-			    "do you want to continue?")))))
+			   (eval-when-compile
+			     (concat
+			      "Autosave file on local temporary directory, "
+			      "do you want to continue?"))))))
 	  (tramp-error v 'file-error "Unsafe autosave file name"))))))
 
 (defun tramp-subst-strs-in-string (alist string)
@@ -6124,7 +6126,7 @@ ALIST is of the form ((FROM . TO) ...)."
       (let* ((pr (car alist))
              (from (car pr))
              (to (cdr pr)))
-        (while (string-match (regexp-quote from) string)
+        (while (string-match (rx (literal from)) string)
           (setq string (replace-match to t t string)))
         (setq alist (cdr alist))))
     string))
@@ -6226,7 +6228,7 @@ verbosity of 6."
 	      (apply #'process-lines program args)
 	    (error
 	     (tramp-error vec (car err) (cdr err)))))
-    (tramp-message vec 6 "%s" result)
+    (tramp-message vec 6 "\n%s" (mapconcat #'identity result "\n"))
     result))
 
 (defun tramp-process-running-p (process-name)
diff --git a/test/lisp/net/tramp-archive-tests.el b/test/lisp/net/tramp-archive-tests.el
index f51037aabb4..964404b4bf7 100644
--- a/test/lisp/net/tramp-archive-tests.el
+++ b/test/lisp/net/tramp-archive-tests.el
@@ -40,7 +40,8 @@
       "Format for `ert-resource-directory'.")
     (defvar ert-resource-directory-trim-left-regexp ""
       "Regexp for `string-trim' (left) used by `ert-resource-directory'.")
-    (defvar ert-resource-directory-trim-right-regexp "\\(-tests?\\)?\\.el"
+    (defvar ert-resource-directory-trim-right-regexp
+      (rx (? "-test" (? "s")) ".el")
       "Regexp for `string-trim' (right) used by `ert-resource-directory'.")
 
     (defmacro ert-resource-directory ()
@@ -615,13 +616,13 @@ This checks also `file-name-as-directory', `file-name-directory',
 	    (insert-directory tramp-archive-test-archive nil)
 	    (goto-char (point-min))
 	    (should
-	     (looking-at-p (regexp-quote tramp-archive-test-archive))))
+	     (looking-at-p (rx (literal tramp-archive-test-archive)))))
 	  (with-temp-buffer
 	    (insert-directory tramp-archive-test-archive "-al")
 	    (goto-char (point-min))
 	    (should
 	     (looking-at-p
-	      (format "^.+ %s$" (regexp-quote tramp-archive-test-archive)))))
+	      (rx bol (+ nonl) " " (literal tramp-archive-test-archive) eol))))
 	  (with-temp-buffer
 	    (insert-directory
 	     (file-name-as-directory tramp-archive-test-archive)
@@ -629,15 +630,17 @@ This checks also `file-name-as-directory', `file-name-directory',
 	    (goto-char (point-min))
 	    (should
 	     (looking-at-p
-	      (concat
-	       ;; There might be a summary line.
-	       "\\(total.+[[:digit:]]+ ?[kKMGTPEZY]?i?B?\n\\)?"
-	       ;; We don't know in which order the files appear.
-	       (format
-		"\\(.+ %s\\( ->.+\\)?\n\\)\\{%d\\}"
-		(regexp-opt (directory-files tramp-archive-test-archive))
-		(length (directory-files tramp-archive-test-archive)))))))
-
+	      (rx-to-string
+	       `(:
+		 ;; There might be a summary line.
+		 (? "total" (+ nonl) (+ digit) (? " ")
+		    (? (any "EGKMPTYZk")) (? "i") (? "B") "\n")
+		 ;; We don't know in which order the files appear.
+		 (= ,(length (directory-files tramp-archive-test-archive))
+		    (+ nonl) " "
+		    (regexp
+		     ,(regexp-opt (directory-files tramp-archive-test-archive)))
+		    (? " ->" (one-or-more nonl)) "\n"))))))
 	  ;; Check error case.
 	  (with-temp-buffer
 	    (should-error
@@ -727,7 +730,7 @@ This tests also `access-file', `file-readable-p' and `file-regular-p'."
 	  (setq attr (directory-files-and-attributes tmp-name 'full))
 	  (dolist (elt attr)
 	    (should (equal (file-attributes (car elt)) (cdr elt))))
-	  (setq attr (directory-files-and-attributes tmp-name nil "\\`b"))
+	  (setq attr (directory-files-and-attributes tmp-name nil (rx bos "b")))
 	  (should (equal (mapcar #'car attr) '("bar"))))
 
       ;; Cleanup.
@@ -914,11 +917,14 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
 	(dolist (file `("/mock::foo" ,(concat tramp-archive-test-archive "foo")))
           (should
            (string-match
-	    (format
-	     "tramp-archive loaded: %s[[:ascii:]]+tramp-archive loaded: %s"
-	     (tramp-archive-file-name-p default-directory)
-	     (or (tramp-archive-file-name-p default-directory)
-		 (and enabled (tramp-archive-file-name-p file))))
+	    (rx "tramp-archive loaded: "
+		(literal (symbol-name
+			  (tramp-archive-file-name-p default-directory)))
+		(+ ascii)
+		"tramp-archive loaded: "
+		(literal (symbol-name
+			  (or (tramp-archive-file-name-p default-directory)
+			     (and enabled (tramp-archive-file-name-p file))))))
 	    (shell-command-to-string
 	     (format
 	      "%s -batch -Q -L %s --eval %s --eval %s"
@@ -955,9 +961,9 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
     (dolist (tae '(t nil))
       (should
        (string-match
-	(format
-	 "tramp-archive loaded: nil[[:ascii:]]+tramp-archive loaded: nil[[:ascii:]]+tramp-archive loaded: %s"
-	 tae)
+	(rx "tramp-archive loaded: nil" (+ ascii)
+	    "tramp-archive loaded: nil" (+ ascii)
+	    "tramp-archive loaded: " (literal (symbol-name tae)))
         (shell-command-to-string
          (format
 	  "%s -batch -Q -L %s --eval %s"
@@ -1005,7 +1011,8 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
 	     (apply
 	      'append
 	      (mapcar
-	       (lambda (x) (directory-files (concat dir x) 'full "uu\\'" 'sort))
+	       (lambda (x)
+		 (directory-files (concat dir x) 'full (rx "uu" eos) 'sort))
 	       '("~/src/libarchive-3.2.2/libarchive/test"
 		 "~/src/libarchive-3.2.2/cpio/test"
 		 "~/src/libarchive-3.2.2/tar/test"))))
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 3e318a729d1..bc67ff2ace7 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -91,7 +91,8 @@
       "Format for `ert-resource-directory'.")
     (defvar ert-resource-directory-trim-left-regexp ""
       "Regexp for `string-trim' (left) used by `ert-resource-directory'.")
-    (defvar ert-resource-directory-trim-right-regexp "\\(-tests?\\)?\\.el"
+    (defvar ert-resource-directory-trim-right-regexp
+      (rx (? "-test" (? "s")) ".el")
       "Regexp for `string-trim' (right) used by `ert-resource-directory'.")
 
     (defmacro ert-resource-directory ()
@@ -204,7 +205,7 @@ being the result.")
     ;; Remove old test files.
     (dolist (dir `(,temporary-file-directory
 		   ,ert-remote-temporary-file-directory))
-      (dolist (file (directory-files dir 'full "\\`\\(\\.#\\)?tramp-test"))
+      (dolist (file (directory-files dir 'full (rx bos (? ".#") "tramp-test")))
 	(ignore-errors
 	  (if (file-directory-p file)
 	      (delete-directory file 'recursive)
@@ -387,15 +388,17 @@ Also see `ignore'."
 	  ;; `tramp-ignored-file-name-regexp' suppresses Tramp.
 	  (let ((tramp-ignored-file-name-regexp "^/method:user@host:"))
 	    (should-not (tramp-tramp-file-p "/method:user@host:")))
-	  ;; Methods shall be at least two characters on MS Windows,
-	  ;; except the default method.
+	  ;; Methods shall be at least two characters, except the
+	  ;; default method.
 	  (let ((system-type 'windows-nt))
 	    (should-not (tramp-tramp-file-p "/c:/path/to/file"))
 	    (should-not (tramp-tramp-file-p "/c::/path/to/file"))
-	    (should (tramp-tramp-file-p "/-::/path/to/file")))
+	    (should (tramp-tramp-file-p "/-::/path/to/file"))
+	    (should (tramp-tramp-file-p "/mm::/path/to/file")))
 	  (let ((system-type 'gnu/linux))
+	    (should-not (tramp-tramp-file-p "/m::/path/to/file"))
 	    (should (tramp-tramp-file-p "/-:h:/path/to/file"))
-	    (should (tramp-tramp-file-p "/m::/path/to/file"))))
+	    (should (tramp-tramp-file-p "/mm::/path/to/file"))))
 
       ;; Exit.
       (tramp-change-syntax syntax))))
@@ -1064,8 +1067,7 @@ Also see `ignore'."
 		   (file-remote-p "/user@email@host:")
 		   (format "/%s@%s:" "user@email" "host")))
 	  (should (string-equal
-		   (file-remote-p
-		    "/user@email@host:" 'method) "default-method"))
+		   (file-remote-p "/user@email@host:" 'method) "default-method"))
 	  (should (string-equal
 		   (file-remote-p "/user@email@host:" 'user) "user@email"))
 	  (should (string-equal
@@ -1474,11 +1476,10 @@ Also see `ignore'."
 		   (file-remote-p "/[method/user@email@host]")
 		   (format "/[%s/%s@%s]" "method" "user@email" "host")))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[method/user@email@host]" 'method) "method"))
+		   (file-remote-p "/[method/user@email@host]" 'method) "method"))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[method/user@email@host]" 'user) "user@email"))
+		   (file-remote-p "/[method/user@email@host]" 'user)
+		   "user@email"))
 	  (should (string-equal
 		   (file-remote-p "/[method/user@email@host]" 'host) "host"))
 	  (should (string-equal
@@ -1505,11 +1506,10 @@ Also see `ignore'."
 		   (file-remote-p "/[/user@host#1234]")
 		   (format "/[%s/%s@%s]" "default-method" "user" "host#1234")))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[/user@host#1234]" 'method) "default-method"))
+		   (file-remote-p "/[/user@host#1234]" 'method)
+		   "default-method"))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[/user@host#1234]" 'user) "user"))
+		   (file-remote-p "/[/user@host#1234]" 'user) "user"))
 	  (should (string-equal
 		   (file-remote-p "/[/user@host#1234]" 'host) "host#1234"))
 	  (should (string-equal
@@ -1535,11 +1535,10 @@ Also see `ignore'."
 		   (file-remote-p "/[-/user@host#1234]")
 		   (format "/[%s/%s@%s]" "default-method" "user" "host#1234")))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[-/user@host#1234]" 'method) "default-method"))
+		   (file-remote-p "/[-/user@host#1234]" 'method)
+		   "default-method"))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[-/user@host#1234]" 'user) "user"))
+		   (file-remote-p "/[-/user@host#1234]" 'user) "user"))
 	  (should (string-equal
 		   (file-remote-p "/[-/user@host#1234]" 'host) "host#1234"))
 	  (should (string-equal
@@ -1569,8 +1568,7 @@ Also see `ignore'."
 	  (should (string-equal
 		   (file-remote-p "/[method/user@host#1234]" 'user) "user"))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[method/user@host#1234]" 'host) "host#1234"))
+		   (file-remote-p "/[method/user@host#1234]" 'host) "host#1234"))
 	  (should (string-equal
 		   (file-remote-p "/[method/user@host#1234]" 'localname) ""))
 	  (should (string-equal
@@ -1595,8 +1593,7 @@ Also see `ignore'."
 		   (file-remote-p "/[/user@1.2.3.4]")
 		   (format "/[%s/%s@%s]" "default-method" "user" "1.2.3.4")))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[/user@1.2.3.4]" 'method) "default-method"))
+		   (file-remote-p "/[/user@1.2.3.4]" 'method) "default-method"))
 	  (should (string-equal
 		   (file-remote-p "/[/user@1.2.3.4]" 'user) "user"))
 	  (should (string-equal
@@ -1624,8 +1621,7 @@ Also see `ignore'."
 		   (file-remote-p "/[-/user@1.2.3.4]")
 		   (format "/[%s/%s@%s]" "default-method" "user" "1.2.3.4")))
 	  (should (string-equal
-		   (file-remote-p
-		    "/[-/user@1.2.3.4]" 'method) "default-method"))
+		   (file-remote-p "/[-/user@1.2.3.4]" 'method) "default-method"))
 	  (should (string-equal
 		   (file-remote-p "/[-/user@1.2.3.4]" 'user) "user"))
 	  (should (string-equal
@@ -2299,9 +2295,9 @@ This checks also `file-name-as-directory', `file-name-directory',
 
     ;; Check `directory-abbrev-alist' abbreviation.
     (let ((directory-abbrev-alist
-           `((,(concat "\\`" (regexp-quote home-dir) "/foo")
+           `((,(rx bos (literal home-dir) "/foo")
               . ,(concat home-dir "/f"))
-             (,(concat "\\`" (regexp-quote remote-host) "/nowhere")
+             (,(rx bos (literal remote-host) "/nowhere")
               . ,(concat remote-host "/nw")))))
       (should (equal (abbreviate-file-name (concat home-dir "/foo/bar"))
                      (concat remote-host-nohop "~/f/bar")))
@@ -2514,8 +2510,8 @@ This checks also `file-name-as-directory', `file-name-directory',
 		     (string-match-p
 		      (if (and (null noninteractive)
 			       (or (eq visit t) (null visit) (stringp visit)))
-			  (format "^Wrote %s\n\\'" (regexp-quote tmp-name))
-			"^\\'")
+			  (rx bol "Wrote " (literal tmp-name) "\n" eos)
+			(rx bos))
 		      tramp--test-messages))))))
 
 	    ;; We do not test lockname here.  See
@@ -3215,38 +3211,40 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 	    (with-temp-buffer
 	      (insert-directory tmp-name1 nil)
 	      (goto-char (point-min))
-	      (should (looking-at-p (regexp-quote tmp-name1))))
+	      (should (looking-at-p (rx (literal tmp-name1)))))
 	    (with-temp-buffer
 	      (insert-directory (file-name-as-directory tmp-name1) nil)
 	      (goto-char (point-min))
 	      (should
                (looking-at-p
-                (regexp-quote (file-name-as-directory tmp-name1)))))
+                (rx (literal (file-name-as-directory tmp-name1))))))
 	    (with-temp-buffer
 	      (insert-directory tmp-name1 "-al")
 	      (goto-char (point-min))
 	      (should
-	       (looking-at-p (format "^.+ %s$" (regexp-quote tmp-name1)))))
+	       (looking-at-p (rx bol (+ nonl) " " (literal tmp-name1) eol))))
 	    (with-temp-buffer
 	      (insert-directory (file-name-as-directory tmp-name1) "-al")
 	      (goto-char (point-min))
 	      (should
-	       (looking-at-p (format "^.+ %s/$" (regexp-quote tmp-name1)))))
-	    (let ((directory-files (directory-files tmp-name1)))
-	      (with-temp-buffer
-		(insert-directory
-		 (file-name-as-directory tmp-name1) "-al" nil 'full-directory-p)
-		(goto-char (point-min))
-		(should
-		 (looking-at-p
-		  (concat
+	       (looking-at-p
+		(rx bol (+ nonl) " " (literal tmp-name1) "/" eol))))
+	    (with-temp-buffer
+	      (insert-directory
+	       (file-name-as-directory tmp-name1) "-al" nil 'full-directory-p)
+	      (goto-char (point-min))
+	      (should
+	       (looking-at-p
+		(rx-to-string
+		 `(:
 		   ;; There might be a summary line.
-		   "\\(total.+[[:digit:]]+ ?[kKMGTPEZY]?i?B?\n\\)?"
+		   (? "total" (+ nonl) (+ digit) (? " ")
+		      (? (any "EGKMPTYZk")) (? "i") (? "B") "\n")
 		   ;; We don't know in which order ".", ".." and "foo" appear.
-		   (format
-		    "\\(.+ %s\\( ->.+\\)?\n\\)\\{%d\\}"
-		    (regexp-opt directory-files)
-		    (length directory-files)))))))
+		   (= ,(length (directory-files tmp-name1))
+		      (+ nonl) " "
+		      (regexp ,(regexp-opt (directory-files tmp-name1)))
+		      (? " ->" (+ nonl)) "\n"))))))
 
 	    ;; Check error cases.
 	    (when (and (tramp--test-supports-set-file-modes-p)
@@ -3274,7 +3272,8 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 (ert-deftest tramp-test17-dired-with-wildcards ()
   "Check `dired' with wildcards."
   ;; `separate' syntax and IPv6 host name syntax do not work.
-  (skip-unless (not (string-match-p "\\[" ert-remote-temporary-file-directory)))
+  (skip-unless
+   (not (string-match-p (rx "[") ert-remote-temporary-file-directory)))
   (skip-unless (tramp--test-enabled))
   (skip-unless (tramp--test-sh-p))
   (skip-unless (not (tramp--test-rsync-p)))
@@ -3313,15 +3312,15 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 	      (goto-char (point-min))
 	      (should
 	       (re-search-forward
-		(regexp-quote
-		 (file-relative-name
-		  tmp-name1 ert-remote-temporary-file-directory))))
+		(rx (literal
+		     (file-relative-name
+		      tmp-name1 ert-remote-temporary-file-directory)))))
 	      (goto-char (point-min))
 	      (should
 	       (re-search-forward
-		(regexp-quote
-		 (file-relative-name
-		  tmp-name2 ert-remote-temporary-file-directory)))))
+		(rx (literal
+		     (file-relative-name
+		      tmp-name2 ert-remote-temporary-file-directory))))))
 	    (kill-buffer buffer)
 
 	    ;; Check for expanded directory and file names.
@@ -3333,16 +3332,16 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 	      (goto-char (point-min))
 	      (should
 	       (re-search-forward
-		(regexp-quote
-		 (file-relative-name
-		  tmp-name3 ert-remote-temporary-file-directory))))
+		(rx (literal
+		     (file-relative-name
+		      tmp-name3 ert-remote-temporary-file-directory)))))
 	      (goto-char (point-min))
 	      (should
 	       (re-search-forward
-		(regexp-quote
-		 (file-relative-name
-		  tmp-name4
-		  ert-remote-temporary-file-directory)))))
+		(rx (literal
+		     (file-relative-name
+		      tmp-name4
+		      ert-remote-temporary-file-directory))))))
 	    (kill-buffer buffer)
 
 	    ;; Check for special characters.
@@ -3361,16 +3360,16 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 	      (goto-char (point-min))
 	      (should
 	       (re-search-forward
-		(regexp-quote
-		 (file-relative-name
-		  tmp-name3 ert-remote-temporary-file-directory))))
+		(rx (literal
+		     (file-relative-name
+		      tmp-name3 ert-remote-temporary-file-directory)))))
 	      (goto-char (point-min))
 	      (should
 	       (re-search-forward
-		(regexp-quote
-		 (file-relative-name
-		  tmp-name4
-		  ert-remote-temporary-file-directory)))))
+		(rx (literal
+		     (file-relative-name
+		      tmp-name4
+		      ert-remote-temporary-file-directory))))))
 	    (kill-buffer buffer))
 
 	;; Cleanup.
@@ -3420,7 +3419,7 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 	       (string-equal
 		(dired-get-filename 'no-dir 'no-error)
 		(file-name-nondirectory tmp-name2)))
-	      (should-not (re-search-forward "dired" nil t))
+	      (should-not (search-forward "dired" nil t))
 	      ;; The copied file has been inserted the line before.
 	      (forward-line -1)
 	      (should
@@ -3766,14 +3765,15 @@ They might differ only in time attributes or directory size."
 	       (tramp--test-file-attributes-equal-p
 		(file-attributes (car elt)) (cdr elt))))
 
-	    (setq attr (directory-files-and-attributes tmp-name2 nil "\\`b"))
+	    (setq attr (directory-files-and-attributes
+			tmp-name2 nil (rx bos "b")))
 	    (should (equal (mapcar #'car attr) '("bar" "boz")))
 
 	    ;; Check the COUNT arg.  It exists since Emacs 28.
 	    (when (tramp--test-emacs28-p)
 	      (with-no-warnings
 		(setq attr (directory-files-and-attributes
-			    tmp-name2 nil "\\`b" nil nil 1))
+			    tmp-name2 nil (rx bos "b") nil nil 1))
 		(should (equal (mapcar #'car attr) '("bar"))))))
 
 	;; Cleanup.
@@ -3879,8 +3879,8 @@ This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
   `(condition-case err
        (progn ,@body)
      (file-error
-      (unless (string-match-p "^error with add-name-to-file"
-			      (error-message-string err))
+      (unless (string-prefix-p "error with add-name-to-file"
+			       (error-message-string err))
 	(signal (car err) (cdr err))))))
 
 (ert-deftest tramp-test21-file-links ()
@@ -4653,7 +4653,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
 	      (let ((process-file-return-signal-string t))
 		(should
 		 (string-match-p
-		  "Interrupt\\|Signal 2"
+		  (rx (| "Interrupt" "Signal 2"))
 		  (process-file
 		   (tramp--test-shell-file-name)
 		   nil nil nil "-c" "kill -2 $$")))))
@@ -4733,7 +4733,8 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
 		(insert-file-contents tmp-name)
 		(should
 		 (string-match-p
-		  "cat:.* No such file or directory" (buffer-string)))
+		  (rx "cat:" (* nonl) " No such file or directory")
+		  (buffer-string)))
 		(should-not (get-buffer-window (current-buffer) t))
 		(delete-file tmp-name))))
 
@@ -4883,8 +4884,8 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
                       ;; On macOS, there is always newline conversion.
 		      ;; "telnet" converts \r to <CR><NUL> if `crlf'
 		      ;; flag is FALSE.  See telnet(1) man page.
-		      "66\n6F\n6F\n0D\\(\n00\\)?\n0A\n"
-		    "66\n6F\n6F\n0A\\(\n00\\)?\n0A\n")
+		      (rx "66\n6F\n6F\n0D" (? "\n00") "\n0A\n")
+		    (rx "66\n6F\n6F\n0A" (? "\n00") "\n0A\n"))
 		  (buffer-string))))
 
 	    ;; Cleanup.
@@ -5081,7 +5082,9 @@ If UNSTABLE is non-nil, the test is tagged as `:unstable'."
 	    (with-timeout (10 (tramp--test-timeout-handler))
 	      (while (accept-process-output proc 0 nil t)))
 	    ;; On some MS Windows systems, it returns "unknown signal".
-	    (should (string-match-p "unknown signal\\|killed" (buffer-string))))
+	    (should
+	     (string-match-p
+	      (rx (| "unknown signal" "killed")) (buffer-string))))
 
 	;; Cleanup.
 	(ignore-errors (delete-process proc)))
@@ -5114,7 +5117,8 @@ If UNSTABLE is non-nil, the test is tagged as `:unstable'."
 		  (delete-process proc)
 		  (should
 		   (string-match-p
-		    "cat:.* No such file or directory" (buffer-string)))))
+		    (rx "cat:" (* nonl) " No such file or directory")
+		    (buffer-string)))))
 
 	    ;; Cleanup.
 	    (ignore-errors (delete-process proc))
@@ -5141,7 +5145,8 @@ If UNSTABLE is non-nil, the test is tagged as `:unstable'."
 		(insert-file-contents tmp-name)
 		(should
 		 (string-match-p
-		  "cat:.* No such file or directory" (buffer-string)))))
+		  (rx "cat:" (* nonl) " No such file or directory")
+		  (buffer-string)))))
 
 	  ;; Cleanup.
 	  (ignore-errors (delete-process proc))
@@ -5192,8 +5197,8 @@ If UNSTABLE is non-nil, the test is tagged as `:unstable'."
                         ;; On macOS, there is always newline conversion.
 			;; "telnet" converts \r to <CR><NUL> if `crlf'
 			;; flag is FALSE.  See telnet(1) man page.
-			"66\n6F\n6F\n0D\\(\n00\\)?\n0A\n"
-		      "66\n6F\n6F\n0A\\(\n00\\)?\n0A\n")
+			(rx "66\n6F\n6F\n0D" (? "\n00") "\n0A\n")
+		      (rx "66\n6F\n6F\n0A" (? "\n00") "\n0A\n"))
 		    (buffer-string))))
 
 	      ;; Cleanup.
@@ -5672,7 +5677,7 @@ INPUT, if non-nil, is a string sent to the process."
 	;; Variable is set.
 	(should
 	 (string-match-p
-	  (regexp-quote envvar)
+	  (rx (literal envvar))
 	  (funcall this-shell-command-to-string "set"))))
 
       (unless (tramp-direct-async-process-p)
@@ -5699,7 +5704,7 @@ INPUT, if non-nil, is a string sent to the process."
 	    ;; Variable is unset.
 	    (should-not
 	     (string-match-p
-	      (regexp-quote envvar)
+	      (rx (literal envvar))
 	      ;; We must remove PS1, the output is truncated otherwise.
 	      ;; We must suppress "_=VAR...".
 	      (funcall
@@ -5851,7 +5856,7 @@ INPUT, if non-nil, is a string sent to the process."
 	    (with-timeout (10)
 	      (while (accept-process-output
 		      (get-buffer-process (current-buffer)) nil nil t)))
-	    (should (string-match-p "^foo$" (buffer-string)))))
+	    (should (string-match-p (rx bol "foo" eol) (buffer-string)))))
 
       ;; Cleanup.
       (put 'explicit-shell-file-name 'permanent-local nil)
@@ -6369,7 +6374,7 @@ INPUT, if non-nil, is a string sent to the process."
 	    ;; When `lock-file-name-transforms' is set, another lock
 	    ;; file is used.
 	    (tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)
-	    (let ((lock-file-name-transforms `((".*" ,tmp-name2))))
+	    (let ((lock-file-name-transforms `((,(rx (* nonl)) ,tmp-name2))))
 	      (should
 	       (string-equal
 		(with-no-warnings (make-lock-file-name tmp-name1))
@@ -6495,10 +6500,12 @@ INPUT, if non-nil, is a string sent to the process."
 		      (insert "bar")
 		      (when create-lockfiles
 			(should (string-match-p
-				 (format
-				  "^%s changed on disk; really edit the buffer\\?"
-				  (if (tramp--test-crypt-p)
-				      ".+" (file-name-nondirectory tmp-name)))
+				 (rx-to-string
+				  `(: bol
+				      ,(if (tramp--test-crypt-p)
+					   '(+ nonl)
+					 (file-name-nondirectory tmp-name))
+				      " changed on disk; really edit the buffer?"))
 				 captured-messages))
 			(should (file-locked-p tmp-name)))))
 
@@ -6589,7 +6596,7 @@ This is used in tests which we don't want to tag
                          :body nil :tags '(:tramp-asynchronous-processes))))
    ;; tramp-adb.el cannot apply multi-byte commands.
    (not (and (tramp--test-adb-p)
-	     (string-match-p "[[:multibyte:]]" default-directory)))))
+	     (string-match-p (rx multibyte) default-directory)))))
 
 (defun tramp--test-crypt-p ()
   "Check, whether the remote directory is encrypted."
@@ -6614,8 +6621,8 @@ completely."
   "Check, whether an FTP-like method is used.
 This does not support globbing characters in file names (yet)."
   ;; Globbing characters are ??, ?* and ?\[.
-  (string-match-p
-   "ftp$" (file-remote-p ert-remote-temporary-file-directory 'method)))
+  (string-suffix-p
+   "ftp" (file-remote-p ert-remote-temporary-file-directory 'method)))
 
 (defun tramp--test-fuse-p ()
   "Check, whether an FUSE file system isused."
@@ -6638,7 +6645,7 @@ If optional METHOD is given, it is checked first."
 Several special characters do not work properly there."
   ;; We must refill the cache.  `file-truename' does it.
   (file-truename ert-remote-temporary-file-directory)
-  (ignore-errors (tramp-check-remote-uname tramp-test-vec "^HP-UX")))
+  (ignore-errors (tramp-check-remote-uname tramp-test-vec (rx bol "HP-UX"))))
 
 (defun tramp--test-ksh-p ()
   "Check, whether the remote shell is ksh.
@@ -6646,8 +6653,9 @@ ksh93 makes some strange conversions of non-latin characters into
 a $'' syntax."
   ;; We must refill the cache.  `file-truename' does it.
   (file-truename ert-remote-temporary-file-directory)
-  (string-match-p
-   "ksh$" (tramp-get-connection-property tramp-test-vec "remote-shell" "")))
+  (string-suffix-p
+   "ksh"
+   (tramp-get-connection-property tramp-test-vec "remote-shell" "")))
 
 (defun tramp--test-macos-p ()
   "Check, whether the remote host runs macOS."
@@ -6695,7 +6703,7 @@ Additionally, ls does not support \"--dired\"."
   "Check, whether the method needs a share."
   (and (tramp--test-gvfs-p)
        (string-match-p
-	"^\\(afp\\|davs?\\|smb\\)$"
+	(rx bol (or "afp" (: "dav" (opt "s")) "smb") eol)
 	(file-remote-p ert-remote-temporary-file-directory 'method))))
 
 (defun tramp--test-sshfs-p ()
@@ -6747,7 +6755,7 @@ This requires restrictions of file name syntax."
       ;; Not all tramp-gvfs.el methods support changing the file mode.
       (and
        (tramp--test-gvfs-p)
-       (string-match-p
+       (string-suffix-p
 	"ftp" (file-remote-p ert-remote-temporary-file-directory 'method)))))
 
 (defun tramp--test-check-files (&rest files)
@@ -6896,14 +6904,14 @@ This requires restrictions of file name syntax."
 		    (should
 		     (string-equal
 		      (caar (directory-files-and-attributes
-			     file1 nil (regexp-quote elt1)))
+			     file1 nil (rx (literal elt1))))
 		      elt1))
 		    (should
 		     (string-equal
 		      (funcall
 		       (if quoted #'tramp-compat-file-name-quote #'identity)
 		       (cadr (car (directory-files-and-attributes
-				   file1 nil (regexp-quote elt1)))))
+				   file1 nil (rx (literal elt1))))))
 		      (file-remote-p (file-truename file2) 'localname)))
 		    (delete-file file3)
 		    (should-not (file-exists-p file3))))
@@ -6958,10 +6966,8 @@ This requires restrictions of file name syntax."
 		    (goto-char (point-min))
 		    (should
 		     (re-search-forward
-		      (format
-		       "^%s=%s$"
-		       (regexp-quote envvar)
-		       (regexp-quote (getenv envvar))))))))))
+		      (rx bol (literal envvar)
+			  "=" (literal (getenv envvar)) eol))))))))
 
 	;; Cleanup.
 	(ignore-errors (kill-buffer buffer))
@@ -7093,7 +7099,7 @@ This requires restrictions of file name syntax."
 	     ;; ?\n and ?/ shouldn't be part of any file name.  ?\t,
 	     ;; ?. and ?? do not work for "smb" method.  " " does not
 	     ;; work at begin or end of the string for MS Windows.
-	     (replace-regexp-in-string "[ \t\n/.?]" "" x)))
+	     (replace-regexp-in-string (rx (any " \t\n/.?")) "" x)))
 	  language-info-alist)))))))
 
 (tramp--test-deftest-with-stat tramp-test42-utf8)
@@ -7476,7 +7482,7 @@ process sentinels.  They shall not disturb each other."
 	  ert-remote-temporary-file-directory)))
     (should
      (string-match-p
-      "Tramp loaded: t[\n\r]+"
+      (rx "Tramp loaded: t" (+ (any "\n\r")))
       (shell-command-to-string
        (format
 	"%s -batch -Q -L %s --eval %s"
@@ -7503,9 +7509,9 @@ process sentinels.  They shall not disturb each other."
     (dolist (tm '(t nil))
       (should
        (string-match-p
-	(format
-       "Tramp loaded: nil[\n\r]+Tramp loaded: nil[\n\r]+Tramp loaded: %s[\n\r]+"
-	 tm)
+	(rx "Tramp loaded: nil" (+ (any "\n\r"))
+	    "Tramp loaded: nil" (+ (any "\n\r"))
+	    "Tramp loaded: " (literal (symbol-name tm)) (+ (any "\n\r")))
 	(shell-command-to-string
 	 (format
 	  "%s -batch -Q -L %s --eval %s"
@@ -7550,11 +7556,10 @@ process sentinels.  They shall not disturb each other."
 	    (tramp-cleanup-all-connections))"))
     (should
      (string-match-p
-      (format
-       "Loading %s"
-       (regexp-quote
-        (expand-file-name
-         "tramp-cmds" (file-name-directory (locate-library "tramp")))))
+      (rx "Loading "
+	  (literal
+           (expand-file-name
+            "tramp-cmds" (file-name-directory (locate-library "tramp")))))
       (shell-command-to-string
        (format
 	"%s -batch -Q -L %s -l tramp-sh --eval %s"
@@ -7595,11 +7600,13 @@ Since it unloads Tramp, it shall be the last test to run."
      (and (or (and (boundp x) (null (local-variable-if-set-p x)))
 	      (and (functionp x) (null (autoloadp (symbol-function x))))
 	      (macrop x))
-	  (string-match-p "^tramp" (symbol-name x))
+	  (string-prefix-p "tramp" (symbol-name x))
 	  ;; `tramp-completion-mode' is autoloaded in Emacs < 28.1.
 	  (not (eq 'tramp-completion-mode x))
-	  (not (string-match-p "^tramp\\(-archive\\)?--?test" (symbol-name x)))
-	  (not (string-match-p "unload-hook$" (symbol-name x)))
+	  (not (string-match-p
+		(rx bol "tramp" (? "-archive") (** 1 2 "-") "test")
+		(symbol-name x)))
+	  (not (string-suffix-p "unload-hook" (symbol-name x)))
 	  (not (get x 'tramp-autoload))
 	  (ert-fail (format "`%s' still bound" x)))))
 
@@ -7609,7 +7616,7 @@ Since it unloads Tramp, it shall be the last test to run."
   (mapatoms
    (lambda (x)
      (and (functionp x) (null (autoloadp (symbol-function x)))
-          (string-match-p "tramp-file-name" (symbol-name x))
+          (string-prefix-p "tramp-file-name" (symbol-name x))
           (ert-fail (format "Structure function `%s' still exists" x)))))
 
   ;; There shouldn't be left a hook function containing a Tramp
@@ -7617,8 +7624,9 @@ Since it unloads Tramp, it shall be the last test to run."
   (mapatoms
    (lambda (x)
      (and (boundp x)
-	  (string-match-p "-\\(hook\\|function\\)s?$" (symbol-name x))
-	  (not (string-match-p "unload-hook$" (symbol-name x)))
+	  (string-match-p
+	   (rx "-" (| "hook" "function") (? "s") eol) (symbol-name x))
+	  (not (string-suffix-p "unload-hook" (symbol-name x)))
 	  (consp (symbol-value x))
 	  (ignore-errors (all-completions "tramp" (symbol-value x)))
 	  (ert-fail (format "Hook `%s' still contains Tramp function" x)))))
@@ -7629,7 +7637,7 @@ Since it unloads Tramp, it shall be the last test to run."
      (and (functionp x)
 	  (advice-mapc
 	   (lambda (fun _symbol)
-	     (and (string-match-p "^tramp" (symbol-name fun))
+	     (and (string-prefix-p "tramp" (symbol-name fun))
 		  (ert-fail
 		   (format "Function `%s' still contains Tramp advice" x))))
 	   x))))
@@ -7646,7 +7654,7 @@ If INTERACTIVE is non-nil, the tests are run interactively."
   (interactive "p")
   (funcall
    (if interactive #'ert-run-tests-interactively #'ert-run-tests-batch)
-   "^tramp"))
+   (rx bol "tramp")))
 
 ;; TODO: