Replace /dev/null by remote null-device in Tramp.

* lisp/net/tramp-adb.el (tramp-adb-get-ls-command)
(tramp-adb-handle-set-file-times, tramp-adb-handle-process-file):
Use `tramp-get-remote-null-device'.

* lisp/net/tramp-compat.el (tramp-tramp-file-p): Declare.
(tramp-compat-null-device): New defalias.

* lisp/net/tramp-sh.el (tramp-methods) <telnet, nc>:
(tramp-perl-encode-with-module, tramp-perl-decode-with-module)
(tramp-perl-encode, tramp-perl-decode, tramp-awk-decode):
Use "%n" marker.
(tramp-do-directory-files-and-attributes-with-stat)
(tramp-sh-handle-file-name-all-completions)
(tramp-do-copy-or-rename-file-out-of-band)
(tramp-sh-handle-insert-directory, tramp-sh-handle-process-file)
(tramp-set-remote-path, tramp-open-connection-setup-interactive-shell)
(tramp-find-inline-encoding, tramp-send-command-and-check)
(tramp-get-remote-path, tramp-get-ls-command, tramp-get-ls-command-with)
(tramp-get-remote-awk, tramp-get-remote-hexdump, tramp-get-remote-od)
(tramp-get-env-with-u-option): Use `tramp-get-remote-null-device'.
(tramp-remote-coding-commands, tramp-call-local-coding-command):
Adapt docstring.

* lisp/net/tramp-smb.el (tramp-smb-conf): Use `null-device'.
(tramp-smb-handle-file-acl): Use `tramp-get-remote-null-device'.

* lisp/net/tramp.el (tramp-methods): Adapt docstring.
(tramp-get-remote-null-device): New defun.
(tramp-interrupt-process): Use it.

5 files changed, 104 insertions, 46 deletions

diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index 750b735c1b9..51cb316249d 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -363,7 +363,8 @@ ARGUMENTS to pass to the OPERATION."
      ;; by GNU Coreutils. Force "ls" to print one column and set
      ;; time-style to imitate other "ls" flavors.
      ((tramp-adb-send-command-and-check
-       vec "ls --time-style=long-iso /dev/null")
+       vec (concat "ls --time-style=long-iso "
+                   (tramp-get-remote-null-device vec)))
       "ls -1 --time-style=long-iso")
      ;; Can't disable coloring explicitly for toybox ls command.  We
      ;; also must force "ls" to print just one column.
@@ -371,7 +372,8 @@ ARGUMENTS to pass to the OPERATION."
      ;; On CyanogenMod based system BusyBox is used and "ls" output
      ;; coloring is enabled by default.  So we try to disable it when
      ;; possible.
-     ((tramp-adb-send-command-and-check vec "ls --color=never -al /dev/null")
+     ((tramp-adb-send-command-and-check
+       vec (concat "ls --color=never -al " (tramp-get-remote-null-device vec)))
       "ls --color=never")
      (t "ls"))))
 
@@ -611,13 +613,13 @@ But handle the case, if the \"test\" command is not available."
       ;; (introduced in POSIX.1-2008) fails.
       (tramp-adb-send-command-and-check
        v (format
-	  (concat "touch -d %s %s %s 2>/dev/null || "
-		  "touch -d %s %s %s 2>/dev/null || "
+	  (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
+	  nofollow quoted-name (tramp-get-remote-null-device v)
 	  (format-time-string "%Y-%m-%dT%H:%M:%S" time t)
-	  nofollow quoted-name
+	  nofollow quoted-name (tramp-get-remote-null-device v)
 	  (format-time-string "%Y%m%d%H%M.%S" time t)
 	  nofollow quoted-name)))))
 
@@ -791,7 +793,7 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 			       (cons program args) " "))
       ;; Determine input.
       (if (null infile)
-	  (setq input "/dev/null")
+	  (setq input (tramp-get-remote-null-device v))
 	(setq infile (expand-file-name infile))
 	(if (tramp-equal-remote default-directory infile)
 	    ;; INFILE is on the same remote host.
@@ -833,7 +835,7 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 		  tmpstderr (tramp-make-tramp-file-name v stderr))))
 	 ;; stderr to be discarded.
 	 ((null (cadr destination))
-	  (setq stderr "/dev/null"))))
+	  (setq stderr (tramp-get-remote-null-device v)))))
        ;; 't
        (destination
 	(setq outbuf (current-buffer))))
diff --git a/lisp/net/tramp-compat.el b/lisp/net/tramp-compat.el
index 9a4e16efe20..7fae9ba7e2f 100644
--- a/lisp/net/tramp-compat.el
+++ b/lisp/net/tramp-compat.el
@@ -43,6 +43,7 @@
 
 ;; `temporary-file-directory' as function is introduced with Emacs 26.1.
 (declare-function tramp-handle-temporary-file-directory "tramp")
+(declare-function tramp-tramp-file-p "tramp")
 (defvar tramp-temp-name-prefix)
 
 (defconst tramp-compat-emacs-compiled-version (eval-when-compile emacs-version)
@@ -333,6 +334,13 @@ A nil value for either argument stands for the current time."
 	   (null (tramp-compat-directory-files
 		  dir nil directory-files-no-dot-files-regexp t 1))))))
 
+;; Function `null-device' is new in Emacs 28.1.
+(defalias 'tramp-compat-null-device
+  (if (fboundp 'null-device)
+      #'null-device
+    (lambda ()
+      (if (tramp-tramp-file-p default-directory) "/dev/null" null-device))))
+
 (add-hook 'tramp-unload-hook
 	  (lambda ()
 	    (unload-feature 'tramp-loaddefs 'force)
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index f9b218a970a..d2265ed1dfa 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -244,14 +244,14 @@ The string is used in `tramp-methods'.")
  (add-to-list 'tramp-methods
               `("telnet"
                 (tramp-login-program        "telnet")
-                (tramp-login-args           (("%h") ("%p") ("2>/dev/null")))
+                (tramp-login-args           (("%h") ("%p") ("%n")))
                 (tramp-remote-shell         ,tramp-default-remote-shell)
                 (tramp-remote-shell-login   ("-l"))
                 (tramp-remote-shell-args    ("-c"))))
  (add-to-list 'tramp-methods
               `("nc"
                 (tramp-login-program        "telnet")
-                (tramp-login-args           (("%h") ("%p") ("2>/dev/null")))
+                (tramp-login-args           (("%h") ("%p") ("%n")))
                 (tramp-remote-shell         ,tramp-default-remote-shell)
                 (tramp-remote-shell-login   ("-l"))
                 (tramp-remote-shell-args    ("-c"))
@@ -262,8 +262,7 @@ The string is used in `tramp-methods'.")
                 ;; We use "-p" as required for newer busyboxes.  For older
                 ;; busybox/nc versions, the value must be (("-l") ("%r")).  This
                 ;; can be achieved by tweaking `tramp-connection-properties'.
-                (tramp-remote-copy-args     (("-l") ("-p" "%r")
-					     ("2>/dev/null")))))
+                (tramp-remote-copy-args     (("-l") ("-p" "%r") ("%n")))))
  (add-to-list 'tramp-methods
               `("su"
                 (tramp-login-program        "su")
@@ -763,7 +762,7 @@ This string is passed to `format', so percent characters need to be doubled.")
 
 ;; These two use base64 encoding.
 (defconst tramp-perl-encode-with-module
-  "%s -MMIME::Base64 -0777 -ne 'print encode_base64($_)' 2>/dev/null"
+  "%s -MMIME::Base64 -0777 -ne 'print encode_base64($_)' %n"
   "Perl program to use for encoding a file.
 Escape sequence %s is replaced with name of Perl binary.
 This string is passed to `format', so percent characters need to be doubled.
@@ -771,7 +770,7 @@ This implementation requires the MIME::Base64 Perl module to be installed
 on the remote host.")
 
 (defconst tramp-perl-decode-with-module
-  "%s -MMIME::Base64 -0777 -ne 'print decode_base64($_)' 2>/dev/null"
+  "%s -MMIME::Base64 -0777 -ne 'print decode_base64($_)' %n"
   "Perl program to use for decoding a file.
 Escape sequence %s is replaced with name of Perl binary.
 This string is passed to `format', so percent characters need to be doubled.
@@ -812,7 +811,7 @@ while (read STDIN, $data, 54) {
             (substr(unpack(q(B*), $data) . q(00000), 0, 432) =~ /....../g)),
               $pad,
                 qq(\\n);
-}' 2>/dev/null"
+}' %n"
   "Perl program to use for encoding a file.
 Escape sequence %s is replaced with name of Perl binary.
 This string is passed to `format', so percent characters need to be doubled.")
@@ -856,7 +855,7 @@ while (my $data = <STDIN>) {
         ((join q(), map {$trans{$_} || q()} split //, $chunk) =~ /......../g);
 
     last if $finished;
-}' 2>/dev/null"
+}' %n"
   "Perl program to use for decoding a file.
 Escape sequence %s is replaced with name of Perl binary.
 This string is passed to `format', so percent characters need to be doubled.")
@@ -938,7 +937,7 @@ BEGIN {
           if (o) {
             printf \"%%c\", o
           } else {
-            system(\"dd if=/dev/zero bs=1 count=1 2>/dev/null\")
+            system(\"dd if=/dev/zero bs=1 count=1 %n\")
           }
           obc=0; o=0
         }
@@ -1785,7 +1784,7 @@ ID-FORMAT valid values are `string' and `integer'."
      "cd %s && echo \"(\"; (%s %s -a | tr '\\n\\r' '\\000\\000' | "
      "xargs -0 %s -c "
      "'(%s%%n%s (%s%%N%s) %%h %s %s %%X %%Y %%Z %%s %s%%A%s t %%i -1)' "
-     "-- 2>/dev/null | sed -e 's/\"/\\\\\"/g' -e 's/%s/\"/g'); echo \")\"")
+     "-- 2>%s | sed -e 's/\"/\\\\\"/g' -e 's/%s/\"/g'); echo \")\"")
     (tramp-shell-quote-argument localname)
     (tramp-get-ls-command vec)
     ;; On systems which have no quoting style, file names with special
@@ -1801,6 +1800,7 @@ ID-FORMAT valid values are `string' and `integer'."
 	"%g"
       (eval-when-compile (concat tramp-stat-marker "%G" tramp-stat-marker)))
     tramp-stat-marker tramp-stat-marker
+    (tramp-get-remote-null-device vec)
     tramp-stat-quoted-marker)))
 
 ;; This function should return "foo/" for directories and "bar" for
@@ -1827,14 +1827,16 @@ ID-FORMAT valid values are `string' and `integer'."
 			  (tramp-shell-quote-argument localname)))
 
 	      (format (concat
-		       "(cd %s 2>&1 && %s -a 2>/dev/null"
+		       "(cd %s 2>&1 && %s -a 2>%s"
 		       " | while IFS= read f; do"
-		       " if %s -d \"$f\" 2>/dev/null;"
+		       " if %s -d \"$f\" 2>%s;"
 		       " then \\echo \"$f/\"; else \\echo \"$f\"; fi; done"
 		       " && \\echo ok) || \\echo fail")
 		      (tramp-shell-quote-argument localname)
 		      (tramp-get-ls-command v)
-		      (tramp-get-test-command v))))
+                      (tramp-get-remote-null-device v)
+		      (tramp-get-test-command v)
+                      (tramp-get-remote-null-device v))))
 
 	   ;; Now grab the output.
 	   (with-current-buffer (tramp-get-buffer v)
@@ -2362,7 +2364,8 @@ The method used must be an out-of-band method."
 	      options (format-spec (tramp-ssh-controlmaster-options v) spec)
 	      spec (format-spec-make
 		    ?h host ?u user ?p port ?r listener ?c options
-		    ?k (if keep-date " " ""))
+		    ?k (if keep-date " " "")
+                    ?n (concat "2>" (tramp-get-remote-null-device v)))
 	      copy-program (tramp-get-method-parameter v 'tramp-copy-program)
 	      copy-keep-date (tramp-get-method-parameter
 			      v 'tramp-copy-keep-date)
@@ -2629,12 +2632,13 @@ The method used must be an out-of-band method."
       (if full-directory-p
 	  (tramp-send-command
 	   v
-	   (format "%s %s %s 2>/dev/null"
+	   (format "%s %s %s 2>%s"
 		   (tramp-get-ls-command v)
 		   switches
 		   (if wildcard
 		       localname
-		     (tramp-shell-quote-argument (concat localname ".")))))
+		     (tramp-shell-quote-argument (concat localname ".")))
+                   (tramp-get-remote-null-device v)))
 	(tramp-barf-unless-okay
 	 v
 	 (format "cd %s" (tramp-shell-quote-argument
@@ -2645,7 +2649,7 @@ The method used must be an out-of-band method."
 	  (tramp-run-real-handler #'file-name-directory (list localname))))
 	(tramp-send-command
 	 v
-	 (format "%s %s %s 2>/dev/null"
+	 (format "%s %s %s 2>%s"
 		 (tramp-get-ls-command v)
 		 switches
 		 (if (or wildcard
@@ -2655,7 +2659,8 @@ The method used must be an out-of-band method."
 		     ""
 		   (tramp-shell-quote-argument
 		    (tramp-run-real-handler
-		     #'file-name-nondirectory (list localname)))))))
+                     #'file-name-nondirectory (list localname))))
+                 (tramp-get-remote-null-device v))))
 
       (save-restriction
 	(let ((beg (point)))
@@ -3146,7 +3151,7 @@ implementation will be used."
                (mapconcat #'tramp-shell-quote-argument uenv " ") command)))
       ;; Determine input.
       (if (null infile)
-	  (setq input "/dev/null")
+	  (setq input (tramp-get-remote-null-device v))
 	(setq infile (expand-file-name infile))
 	(if (tramp-equal-remote default-directory infile)
 	    ;; INFILE is on the same remote host.
@@ -3188,7 +3193,7 @@ implementation will be used."
 		  tmpstderr (tramp-make-tramp-file-name v stderr 'nohop))))
 	 ;; stderr to be discarded.
 	 ((null (cadr destination))
-	  (setq stderr "/dev/null"))))
+	  (setq stderr (tramp-get-remote-null-device v)))))
        ;; 't
        (destination
 	(setq outbuf (current-buffer))))
@@ -4117,7 +4122,10 @@ variable PATH."
 	(pipe-buf
 	 (with-tramp-connection-property vec "pipe-buf"
 	   (tramp-send-command-and-read
-	    vec "getconf PIPE_BUF / 2>/dev/null || echo 4096" 'noerror)))
+	    vec
+            (format "getconf PIPE_BUF / 2>%s || echo 4096"
+                    (tramp-get-remote-null-device vec))
+            'noerror)))
 	tmpfile chunk chunksize)
     (tramp-message vec 5 "Setting $PATH environment variable")
     (if (< (length command) pipe-buf)
@@ -4439,7 +4447,12 @@ process to set up.  VEC specifies the connection."
     (tramp-find-shell vec)
 
     ;; Disable unexpected output.
-    (tramp-send-command vec "mesg n 2>/dev/null; biff n 2>/dev/null" t)
+    (tramp-send-command
+     vec
+     (format "mesg n 2>%s; biff n 2>%s"
+             (tramp-get-remote-null-device vec)
+             (tramp-get-remote-null-device vec))
+     t)
 
     ;; IRIX64 bash expands "!" even when in single quotes.  This
     ;; destroys our shell functions, we must disable it.  See
@@ -4454,7 +4467,8 @@ process to set up.  VEC specifies the connection."
 
     ;; Set utf8 encoding.  Needed for macOS, for example.  This is
     ;; non-POSIX, so we must expect errors on some systems.
-    (tramp-send-command vec "stty iutf8 2>/dev/null" t)
+    (tramp-send-command
+     vec (concat "stty iutf8 2>" (tramp-get-remote-null-device vec)) t)
 
     ;; Set `remote-tty' process property.
     (let ((tty (tramp-send-command-and-read vec "echo \\\"`tty`\\\"" 'noerror)))
@@ -4570,7 +4584,8 @@ program will be transferred to the remote host, and it is
 available as shell function with the same name.  A \"%t\" format
 specifier in the variable value denotes a temporary file.
 \"%a\", \"%h\" and \"%o\" format specifiers are replaced by the
-respective `awk', `hexdump' and `od' commands.
+respective `awk', `hexdump' and `od' commands.  \"%n\" is
+replaced by \"2>/dev/null\".
 
 The optional TEST command can be used for further tests, whether
 ENCODING and DECODING are applicable.")
@@ -4657,6 +4672,8 @@ Goes through the list `tramp-local-coding-commands' and
 			       (format-spec-make
 				?a (tramp-get-remote-awk vec)
 				?h (tramp-get-remote-hexdump vec)
+				?n (concat
+                                    "2>" (tramp-get-remote-null-device vec))
 				?o (tramp-get-remote-od vec)))
 			      value (replace-regexp-in-string "%" "%%" value)))
 		      (tramp-maybe-send-script vec value name)
@@ -4665,7 +4682,10 @@ Goes through the list `tramp-local-coding-commands' and
 		   vec 5
 		   "Checking remote encoding command `%s' for sanity" rem-enc)
 		  (unless (tramp-send-command-and-check
-			   vec (format "%s </dev/null" rem-enc) t)
+			   vec
+                           (format
+                            "%s <%s" rem-enc (tramp-get-remote-null-device vec))
+                           t)
 		    (throw 'wont-work-remote nil))
 
 		  (unless (stringp rem-dec)
@@ -4681,6 +4701,8 @@ Goes through the list `tramp-local-coding-commands' and
 			       (format-spec-make
 				?a (tramp-get-remote-awk vec)
 				?h (tramp-get-remote-hexdump vec)
+				?n (concat
+                                    "2>" (tramp-get-remote-null-device vec))
 				?o (tramp-get-remote-od vec)))
 			      value (replace-regexp-in-string "%" "%%" value)))
 		      (when (string-match-p "\\(^\\|[^%]\\)%t" value)
@@ -4727,7 +4749,7 @@ Goes through the list `tramp-local-coding-commands' and
   "Call the local encoding or decoding command.
 If CMD contains \"%s\", provide input file INPUT there in command.
 Otherwise, INPUT is passed via standard input.
-INPUT can also be nil which means `/dev/null'.
+INPUT can also be nil which means `null-device'.
 OUTPUT can be a string (which specifies a file name), or t (which
 means standard output and thus the current buffer), or nil (which
 means discard it)."
@@ -5199,14 +5221,17 @@ status is 0, and nil otherwise.
 
 If the optional argument SUBSHELL is non-nil, the command is
 executed in a subshell, ie surrounded by parentheses.  If
-DONT-SUPPRESS-ERR is non-nil, stderr won't be sent to /dev/null.
+DONT-SUPPRESS-ERR is non-nil, stderr won't be sent to \"/dev/null\".
 Optional argument EXIT-STATUS, if non-nil, triggers the return of
 the exit status."
   (tramp-send-command
    vec
    (concat (if subshell "( " "")
 	   command
-	   (if command (if dont-suppress-err "; " " 2>/dev/null; ") "")
+	   (if command
+               (if dont-suppress-err
+                   "; " (format " 2>%s; " (tramp-get-remote-null-device vec)))
+             "")
 	   "echo tramp_exit_status $?"
 	   (if subshell " )" "")))
   (with-current-buffer (tramp-get-connection-buffer vec)
@@ -5416,7 +5441,11 @@ Nonexistent directories are removed from spec."
 	       (when elt1
 		 (or
 		  (tramp-send-command-and-read
-		   vec "echo \\\"`getconf PATH 2>/dev/null`\\\"" 'noerror)
+		   vec
+                   (format
+                    "echo \\\"`getconf PATH 2>%s`\\\""
+                    (tramp-get-remote-null-device vec))
+                   'noerror)
 		  ;; Default if "getconf" is not available.
 		  (progn
 		    (tramp-message
@@ -5520,7 +5549,8 @@ Nonexistent directories are removed from spec."
 		    vec (format "%s -lnd /" result))
 	       (when (tramp-send-command-and-check
 		      vec (format
-			   "%s --color=never -al /dev/null" result))
+			   "%s --color=never -al %s"
+                           result (tramp-get-remote-null-device vec)))
 		 (setq result (concat result " --color=never")))
 	       (throw 'ls-found result))
 	     (setq dl (cdr dl))))))
@@ -5541,7 +5571,9 @@ Nonexistent directories are removed from spec."
        (format
 	"%s --help 2>&1 | grep -iq busybox" (tramp-get-ls-command vec))))
      (tramp-send-command-and-check
-      vec (format "%s %s -al /dev/null" (tramp-get-ls-command vec) option))
+      vec (format
+           "%s %s -al %s"
+           (tramp-get-ls-command vec) option (tramp-get-remote-null-device vec)))
      option)))
 
 (defun tramp-get-test-command (vec)
@@ -5820,7 +5852,7 @@ This command is returned only if `delete-by-moving-to-trash' is non-nil."
 	       (command (format "%s %s" busybox "awk")))
 	  (and busybox
 	       (tramp-send-command-and-check
-		vec (concat command " {} </dev/null"))
+		vec (concat command " {} <" (tramp-get-remote-null-device vec)))
 	       command)))))
 
 (defun tramp-get-remote-hexdump (vec)
@@ -5831,7 +5863,8 @@ This command is returned only if `delete-by-moving-to-trash' is non-nil."
 	(let* ((busybox (tramp-get-remote-busybox vec))
 	       (command (format "%s %s" busybox "hexdump")))
 	  (and busybox
-	       (tramp-send-command-and-check vec (concat command " </dev/null"))
+	       (tramp-send-command-and-check
+                vec (concat command " <" (tramp-get-remote-null-device vec)))
 	       command)))))
 
 (defun tramp-get-remote-od (vec)
@@ -5843,7 +5876,8 @@ This command is returned only if `delete-by-moving-to-trash' is non-nil."
 	       (command (format "%s %s" busybox "od")))
 	  (and busybox
 	       (tramp-send-command-and-check
-		vec (concat command " -A n </dev/null"))
+		vec
+                (concat command " -A n <" (tramp-get-remote-null-device vec)))
 	       command)))))
 
 (defun tramp-get-remote-chmod-h (vec)
@@ -5865,7 +5899,9 @@ This command is returned only if `delete-by-moving-to-trash' is non-nil."
     (tramp-message vec 5 "Checking, whether `env -u' works")
     ;; Option "-u" is a GNU extension.
     (tramp-send-command-and-check
-     vec "env FOO=foo env -u FOO 2>/dev/null | grep -qv FOO" t)))
+     vec (format "env FOO=foo env -u FOO 2>%s | grep -qv FOO"
+                 (tramp-get-remote-null-device vec))
+     t)))
 
 ;; Some predefined connection properties.
 (defun tramp-get-inline-compress (vec prop size)
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index 8a48ffc09b8..cafa97cec09 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -74,7 +74,7 @@
   :version "24.4")
 
 ;;;###tramp-autoload
-(defcustom tramp-smb-conf "/dev/null"
+(defcustom tramp-smb-conf null-device
   "Path of the \"smb.conf\" file.
 If it is nil, no \"smb.conf\" will be added to the `tramp-smb-program'
 call, letting the SMB client use the default one."
@@ -797,7 +797,7 @@ PRESERVE-UID-GID and PRESERVE-EXTENDED-ATTRIBUTES are completely ignored."
 	    (setq
 	     args
 	     (append args (list (tramp-unquote-shell-quote-argument localname)
-				"2>/dev/null")))
+				(concat "2>" (tramp-get-remote-null-device v)))))
 
 	    (unwind-protect
 		(with-temp-buffer
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index a98d478bc1a..d40f9a5927c 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -238,6 +238,7 @@ pair of the form (KEY VALUE).  The following KEYs are defined:
     - \"%k\" indicates the keep-date parameter of a program, if exists.
     - \"%c\" adds additional `tramp-ssh-controlmaster-options'
       options for the first hop.
+    - \"%n\" expands to \"2>/dev/null\".
 
     The existence of `tramp-login-args', combined with the
     absence of `tramp-copy-args', is an indication that the
@@ -5325,7 +5326,9 @@ name of a process or buffer, or nil to default to the current buffer."
 	(tramp-compat-funcall
 	 'tramp-send-command
 	 (process-get proc 'vector)
-	 (format "(\\kill -2 -%d || \\kill -2 %d) 2>/dev/null" pid pid))
+	 (format "(\\kill -2 -%d || \\kill -2 %d) 2>%s"
+                 pid pid
+                 (tramp-get-remote-null-device (process-get proc 'vector))))
 	;; Wait, until the process has disappeared.  If it doesn't,
 	;; fall back to the default implementation.
         (while (tramp-accept-process-output proc 0))
@@ -5339,6 +5342,15 @@ name of a process or buffer, or nil to default to the current buffer."
    (lambda ()
      (remove-hook 'interrupt-process-functions #'tramp-interrupt-process))))
 
+(defun tramp-get-remote-null-device (vec)
+  "Return null device on the remote host identified by VEC.
+If VEC is nil, return local null device."
+  (if (null vec)
+      null-device
+    (with-tramp-connection-property vec "null-device"
+      (let ((default-directory (tramp-make-tramp-file-name vec)))
+        (tramp-compat-null-device)))))
+
 (defmacro tramp-skeleton-delete-directory (directory recursive trash &rest body)
   "Skeleton for `tramp-*-handle-delete-directory'.
 BODY is the backend specific code."