@c This is part of the Emacs manual.
@c Copyright (C) 1985--1987, 1993--1995, 1997, 2000--2025 Free Software
@c Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Dired
@chapter Dired, the Directory Editor
@c This node is referenced in the tutorial.  When renaming or deleting
@c it, the tutorial needs to be adjusted.
@cindex Dired
@cindex file management

  Dired makes an Emacs buffer containing a listing of a directory, and
optionally some of its subdirectories as well.  You can use the normal
Emacs commands to move around in this buffer, and special Dired
commands to operate on the listed files.  Dired works with both local
and remote directories.

  The Dired buffer is normally read-only, and inserting text in it is
not allowed (however, the Wdired mode allows that, @pxref{Wdired}).
Ordinary printing characters such as @kbd{d} and @kbd{x} are
redefined for special Dired commands.  Some Dired commands @dfn{mark}
or @dfn{flag} the @dfn{current file} (that is, the file on the current
line); other commands operate on the marked files or on the flagged
files.  You first mark certain files in order to operate on all of
them with one command.

  The Dired-X package provides various extra features for Dired mode.
@xref{Top, Dired-X,,dired-x, Dired Extra User's Manual}.

  You can also view a list of files in a directory with @kbd{C-x C-d}
(@code{list-directory}).  Unlike Dired, this command does not allow
you to operate on the listed files.  @xref{Directories}.

@menu
* Enter: Dired Enter.         How to invoke Dired.
* Navigation: Dired Navigation.   Special motion commands in the Dired buffer.
* Deletion: Dired Deletion.   Deleting files with Dired.
* Flagging Many Files::       Flagging files based on their names.
* Visit: Dired Visiting.      Other file operations through Dired.
* Marks vs Flags::            Flagging for deletion vs marking.
* Operating on Files::        How to copy, rename, print, compress, etc.
                                either one file or several files.
* Shell Commands in Dired::   Running a shell command on the marked files.
* Shell Command Guessing::    Guessing shell commands for files.
* Transforming File Names::   Using patterns to rename multiple files.
* Comparison in Dired::       Running @code{diff} by way of Dired.
* Subdirectories in Dired::   Adding subdirectories to the Dired buffer.
@ifnottex
* Subdir Switches::           Subdirectory switches in Dired.
@end ifnottex
* Subdirectory Motion::       Moving across subdirectories, and up and down.
* Hiding Subdirectories::     Making subdirectories visible or invisible.
* Updating: Dired Updating.   Discarding lines for files of no interest.
* Find: Dired and Find.       Using @code{find} to choose the files for Dired.
* Wdired::                    Operating on files by editing the Dired buffer.
* Image-Dired::               Viewing image thumbnails in Dired.
* Misc: Misc Dired Features.  Various other features.
@end menu

@node Dired Enter
@section Entering Dired

@findex dired
@kindex C-x d
@vindex dired-listing-switches
  To invoke Dired, type @kbd{C-x d} (@code{dired}).  This reads a
directory's name using the minibuffer, and opens a @dfn{Dired buffer}
listing the files in that directory.  You can also supply a wildcard
file name pattern as the minibuffer argument, in which case the Dired
buffer lists all files matching that pattern.  A wildcard may appear
in the directory part as well.
For instance,

@example
C-x d  ~/foo/*.el  @key{RET}
C-x d  ~/foo/*/*.el  @key{RET}
@end example

The former lists all the files with extension @samp{.el} in directory
@samp{foo}.  The latter lists the files with extension @samp{.el}
in all the subdirectories of @samp{foo}.

@cindex globstar, in Dired
On Posix systems, when the system shell supports @dfn{globstar}, a
recursive globbing feature, and that support is enabled, you can use
recursive globbing in Dired:

@example
C-x d  ~/foo/**/*.el  @key{RET}
@end example

This command produces a directory listing with all the files with
extension @samp{.el}, descending recursively in all the subdirectories
of @samp{foo}.  Note that there are small differences in the
implementation of globstar between different shells.  Check your shell
manual to know the expected behavior.

@vindex dired-maybe-use-globstar
@vindex dired-enable-globstar-in-shell
If the shell supports globstar, but that support is disabled by
default, you can still let Dired use this feature by customizing
@code{dired-maybe-use-globstar} to a non-@code{nil} value; then Dired
will enable globstar for those shells for which it knows how (see
@code{dired-enable-globstar-in-shell} for the list of those shells).

The usual history and completion commands can be used in the minibuffer;
in particular, @kbd{M-n} puts the name of the visited file (if any) in
the minibuffer (@pxref{Minibuffer History}).

  You can also invoke Dired by giving @kbd{C-x C-f} (@code{find-file})
a directory's name.

@findex dired-jump
@findex dired-jump-other-window
@kindex C-x C-j
@kindex C-x 4 C-j
  You can ask Emacs to invoke Dired on the default-directory
(@pxref{File Names, default-directory}) of any buffer, by typing
@kbd{C-x C-j} (@code{dired-jump}).  If the buffer visits a file, this
command will move point to that file's line in the Dired buffer it
shows; otherwise, point will end up on the first file in the directory
listing.  As an exception, if you type @kbd{C-x C-j} in a Dired
buffer, Emacs displays the directory listing of the parent directory
and places point on the line that corresponds to the directory where
you invoked @code{dired-jump}.  Typing @kbd{C-x 4 C-j}
(@code{dired-jump-other-window}) has the same effect, but displays the
Dired buffer in a new window.

  The variable @code{dired-listing-switches} specifies the options to
give to @command{ls} for listing the directory; this string
@emph{must} contain @samp{-l}.  If you use a prefix argument with the
@code{dired} command, you can specify the @command{ls} switches with the
minibuffer before you enter the directory specification.  No matter
how they are specified, the @command{ls} switches can include short
options (that is, single characters) requiring no arguments, and long
options (starting with @samp{--}) whose arguments are specified with
@samp{=}.

  Dired does not handle files that have names with embedded newline
characters well.  If you have many such files, you may consider adding
@samp{-b} to @code{dired-listing-switches}.  This will quote all
special characters and allow Dired to handle them better.  (You can
also use the @kbd{C-u C-x d} command to add @samp{-b} temporarily.)

@code{dired-listing-switches} can be declared as connection-local
variable to adjust it to match what a remote system expects
(@pxref{Connection Variables}).

@vindex dired-switches-in-mode-line
  Dired displays in the mode line an indication of what were the
switches used to invoke @command{ls}.  By default, Dired will try to
determine whether the switches indicate sorting by name or date, and
will say so in the mode line.  If the @code{dired-switches-in-mode-line}
variable is @code{as-is}, the switches will be shown verbatim.  If
this variable's value is an integer, the switch display will be
truncated to that length.  This variable can also be a function, which
will be called with @code{dired-actual-switches} as the only
parameter, and should return a string to display in the mode line.

@vindex dired-use-ls-dired
  If your @command{ls} program supports the @samp{--dired} option,
Dired automatically passes it that option; this causes @command{ls} to
emit special escape sequences for certain unusual file names, without
which Dired will not be able to parse those names.  The first time you
run Dired in an Emacs session, it checks whether @command{ls} supports
the @samp{--dired} option by calling it once with that option.  If the
exit code is 0, Dired will subsequently use the @samp{--dired} option;
otherwise it will not.  You can inhibit this check by customizing the
variable @code{dired-use-ls-dired}.  The value @code{unspecified} (the
default) means to perform the check; any other non-@code{nil} value
means to use the @samp{--dired} option; and @code{nil} means not to
use the @samp{--dired} option.

  On MS-Windows and MS-DOS systems, and also on some remote systems,
Emacs emulates @command{ls}.  @xref{ls in Lisp}, for options and
peculiarities of this emulation.

@findex dired-other-window
@kindex C-x 4 d
@findex dired-other-frame
@kindex C-x 5 d
  To display the Dired buffer in another window, use @kbd{C-x 4 d}
(@code{dired-other-window}).  @kbd{C-x 5 d}
(@code{dired-other-frame}) displays the Dired buffer in a separate
frame.

@kindex q @r{(Dired)}
@findex quit-window@r{, in Dired buffers}
  Typing @kbd{q} (@code{quit-window}) buries the Dired buffer, and
deletes its window if the window was created just for that buffer.

@node Dired Navigation
@section Navigation in the Dired Buffer

@kindex C-n @r{(Dired)}
@kindex C-p @r{(Dired)}
@findex dired-next-line
@findex dired-previous-line
  All the usual Emacs cursor motion commands are available in Dired
buffers.  The keys @kbd{C-n} and @kbd{C-p} are redefined to run
@code{dired-next-line} and @code{dired-previous-line}, respectively,
and they put the cursor at the beginning of the file name on the line,
rather than at the beginning of the line.

@kindex SPC @r{(Dired)}
  For extra convenience, @key{SPC} and @kbd{n} in Dired are equivalent
to @kbd{C-n}.  @kbd{p} is equivalent to @kbd{C-p}.  (Moving by lines
is so common in Dired that it deserves to be easy to type.)  @key{DEL}
(move up and unflag) is also often useful simply for moving up
(@pxref{Dired Deletion}).

@findex dired-goto-file
@kindex j @r{(Dired)}
  @kbd{j} (@code{dired-goto-file}) prompts for a file name using the
minibuffer, and moves point to the line in the Dired buffer describing
that file.

@cindex searching Dired buffers
@findex dired-isearch-filenames
@vindex dired-isearch-filenames
@findex dired-isearch-filenames-regexp
@kindex M-s f C-s @r{(Dired)}
@kindex M-s f M-C-s @r{(Dired)}
  @kbd{M-s f C-s} (@code{dired-isearch-filenames}) performs a forward
incremental search in the Dired buffer, looking for matches only
amongst the file names and ignoring the rest of the text in the
buffer.  @kbd{M-s f M-C-s} (@code{dired-isearch-filenames-regexp})
does the same, using a regular expression search.  If you change the
variable @code{dired-isearch-filenames} to @code{t}, then the
usual search commands also limit themselves to the file names; for
instance, @kbd{C-s} behaves like @kbd{M-s f C-s}.  If the value is
@code{dwim}, then search commands match the file names only when point
was on a file name initially.  @xref{Search}, for information about
incremental search.

  Some additional navigation commands are available when the Dired
buffer includes several directories.  @xref{Subdirectory Motion}.

@node Dired Deletion
@section Deleting Files with Dired
@cindex flagging files (in Dired)
@cindex deleting files (in Dired)

  One of the most frequent uses of Dired is to first @dfn{flag} files for
deletion, then delete the files that were flagged.

@table @kbd
@item d
Flag this file for deletion (@code{dired-flag-file-deletion}).
@item u
Remove the deletion flag (@code{dired-unmark}).
@item @key{DEL}
Move point to previous line and remove the deletion flag on that line
(@code{dired-unmark-backward}).
@item x
Delete files flagged for deletion (@code{dired-do-flagged-delete}).
@end table

@kindex d @r{(Dired)}
@findex dired-flag-file-deletion
  You can flag a file for deletion by moving to the line describing
the file and typing @kbd{d} (@code{dired-flag-file-deletion}).  The
deletion flag is visible as a @samp{D} at the beginning of the line.
This command moves point to the next line, so that repeated @kbd{d}
commands flag successive files.  A numeric prefix argument serves as a
repeat count; a negative count means to flag preceding files.

  If the region is active, the @kbd{d} command flags all files in the
region for deletion; in this case, the command does not move point,
and ignores any prefix argument.

@kindex u @r{(Dired deletion)}
@kindex DEL @r{(Dired)}
  The reason for flagging files for deletion, rather than deleting
files immediately, is to reduce the danger of deleting a file
accidentally.  Until you direct Dired to delete the flagged files, you
can remove deletion flags using the commands @kbd{u} and @key{DEL}.
@kbd{u} (@code{dired-unmark}) works just like @kbd{d}, but removes
flags rather than making flags.  @key{DEL}
(@code{dired-unmark-backward}) moves upward, removing flags; it is
like @kbd{u} with argument @minus{}1.  A numeric prefix argument to
either command serves as a repeat count, with a negative count meaning
to unflag in the opposite direction.  If the region is active, these
commands instead unflag all files in the region, without moving point.

@kindex x @r{(Dired)}
@findex dired-do-flagged-delete
  To delete flagged files, type @kbd{x}
(@code{dired-do-flagged-delete}).  This command displays a list of all
the file names flagged for deletion, and requests confirmation with
@kbd{yes}.  If you confirm, Dired deletes the flagged files, then
deletes their lines from the text of the Dired buffer.  The Dired
buffer, with somewhat fewer lines, remains selected.

  If you answer @kbd{no} or quit with @kbd{C-g} when asked to confirm, you
return immediately to Dired, with the deletion flags still present in
the buffer, and no files actually deleted.

@cindex recursive deletion
@vindex dired-recursive-deletes
  You can delete empty directories just like other files, but normally
Dired cannot delete directories that are nonempty.  However, if the
variable @code{dired-recursive-deletes} is non-@code{nil}, then Dired
is allowed to delete nonempty directories including all their
contents.  That can be somewhat risky.  If the value of the variable
is @code{always}, Dired will delete nonempty directories recursively,
which is even more risky.

Even if you have set @code{dired-recursive-deletes} to @code{nil}, you
might want sometimes to delete directories recursively without being
asked for confirmation for all of them.  For example, you may want
that when you have marked many directories for deletion and you are
very sure that all of them can safely be deleted.  For every nonempty
directory you are asked for confirmation to delete, if you answer
@code{all}, then all the remaining directories will be deleted without
any further questions.

@vindex delete-by-moving-to-trash@r{, and Dired}
  If you change the variable @code{delete-by-moving-to-trash} to
@code{t}, the above deletion commands will move the affected files or
directories into the operating system's Trash, instead of deleting
them outright.  @xref{Misc File Ops}.

  An alternative way of deleting files is to mark them with @kbd{m}
and delete with @kbd{D}, see @ref{Operating on Files}.

@node Flagging Many Files
@section Flagging Many Files at Once
@cindex flagging many files for deletion (in Dired)

  The @kbd{#}, @kbd{~}, @kbd{.}, @kbd{% &}, and @kbd{% d} commands
flag many files for deletion, based on their file names:

@table @kbd
@item #
Flag all auto-save files (files whose names start and end with @samp{#})
for deletion (@pxref{Auto Save}).

@item ~
Flag all backup files (files whose names end with @samp{~}) for deletion
(@pxref{Backup}).

@item .@: @r{(Period)}
Flag excess numeric backup files for deletion.  The oldest and newest
few backup files of any one file are exempt; the middle ones are
flagged.

@item % &
Flag for deletion all files with certain kinds of names which suggest
you could easily create those files again.

@item % d @var{regexp} @key{RET}
Flag for deletion all files whose names match the regular expression
@var{regexp}.
@end table

@kindex # @r{(Dired)}
@findex dired-flag-auto-save-files
@cindex deleting auto-save files
  @kbd{#} (@code{dired-flag-auto-save-files}) flags all files whose
names look like auto-save files---that is, files whose names begin and
end with @samp{#}.  @xref{Auto Save}.

@kindex ~ @r{(Dired)}
@findex dired-flag-backup-files
  @kbd{~} (@code{dired-flag-backup-files}) flags all files whose names
say they are backup files---that is, files whose names end in
@samp{~}.  @xref{Backup}.

@kindex . @r{(Dired)}
@vindex dired-kept-versions
@findex dired-clean-directory
  @kbd{.} (period, @code{dired-clean-directory}) flags just some of
the backup files for deletion: all but the oldest few and newest few
backups of any one file.  Normally, the number of newest versions kept
for each file is given by the variable @code{dired-kept-versions}
(@emph{not} @code{kept-new-versions}; that applies only when saving).
The number of oldest versions to keep is given by the variable
@code{kept-old-versions}.

  Period with a positive numeric argument, as in @kbd{C-u 3 .},
specifies the number of newest versions to keep, overriding
@code{dired-kept-versions}.  A negative numeric argument overrides
@code{kept-old-versions}, using minus the value of the argument to
specify the number of oldest versions of each file to keep.

@kindex % & @r{(Dired)}
@findex dired-flag-garbage-files
@vindex dired-garbage-files-regexp
@cindex deleting some backup files
  @kbd{% &} (@code{dired-flag-garbage-files}) flags files whose names
match the regular expression specified by the variable
@code{dired-garbage-files-regexp}.  By default, this matches certain
files produced by @TeX{}, @samp{.bak} files, and the @samp{.orig} and
@samp{.rej} files produced by @code{patch}.

@findex dired-flag-files-regexp
@kindex % d @r{(Dired)}
  @kbd{% d} flags all files whose names match a specified regular
expression (@code{dired-flag-files-regexp}).  Only the non-directory
part of the file name is used in matching.  You can use @samp{^} and
@samp{$} to anchor matches.  You can exclude certain subdirectories
from marking by hiding them while you use @kbd{% d}.  @xref{Hiding
Subdirectories}.

@node Dired Visiting
@section Visiting Files in Dired

  There are several Dired commands for visiting or examining the files
listed in the Dired buffer.  All of them apply to the current line's
file; if that file is really a directory, these commands invoke Dired on
that subdirectory (making a separate Dired buffer).

@table @kbd
@item f
@kindex f @r{(Dired)}
@findex dired-find-file
Visit the file described on the current line, like typing @kbd{C-x C-f}
and supplying that file name (@code{dired-find-file}).  @xref{Visiting}.

@item @key{RET}
@itemx e
@kindex RET @r{(Dired)}
@kindex e @r{(Dired)}
Equivalent to @kbd{f}.

@ignore  @c This command seems too risky to document at all.
@item a
@kindex a @r{(Dired)}
@findex dired-find-alternate-file
Like @kbd{f}, but replaces the contents of the Dired buffer with
that of an alternate file or directory (@code{dired-find-alternate-file}).
@end ignore

@item o
@kindex o @r{(Dired)}
@findex dired-find-file-other-window
Like @kbd{f}, but uses another window to display the file's buffer
(@code{dired-find-file-other-window}).  The Dired buffer remains visible
in the first window.  This is like using @kbd{C-x 4 C-f} to visit the
file.  @xref{Windows}.

@item C-o
@kindex C-o @r{(Dired)}
@findex dired-display-file
Visit the file described on the current line, and display the buffer in
another window, but do not select that window (@code{dired-display-file}).

@item mouse-1
@itemx mouse-2
@findex dired-mouse-find-file-other-window
Visit the file whose name you clicked on
(@code{dired-mouse-find-file-other-window}).  This uses another window
to display the file, like the @kbd{o} command.

@item v
@kindex v @r{(Dired)}
@findex dired-view-file
View the file described on the current line, with View mode
(@code{dired-view-file}).  View mode provides convenient commands to
navigate the buffer but forbids changing it; @xref{View Mode}.

@item @@
@kindex @@ @r{(Dired)}
@findex tramp-dired-find-file-with-sudo
Open the file described on the current line, with superuser, or root,
permissions (@code{tramp-dired-find-file-with-sudo}).  If called with a
@kbd{C-u} prefix argument, it prompts for another Tramp method to use
other than the default, @option{sudo}.  @xref{Ad-hoc multi-hops, Tramp,,
tramp, The Tramp Manual}.

@item ^
@kindex ^ @r{(Dired)}
@findex dired-up-directory
Visit the parent directory of the current directory
(@code{dired-up-directory}).  This is equivalent to moving to the line
for @file{..} and typing @kbd{f} there.
@end table

@defopt dired-kill-when-opening-new-dired-buffer
  When visiting a new sub-directory in Dired, Emacs will (by default)
open a new buffer to display this new directory, and leave the old
Dired buffer as is.  If this user option is non-@code{nil}, the old
Dired buffer will be killed after selecting the new directory.  This
means that if you're traversing a directory structure in Dired, you
won't end up with more than a single Dired buffer.
@end defopt

@node Marks vs Flags
@section Dired Marks vs.@: Flags

@cindex marking many files (in Dired)
  Instead of flagging a file with @samp{D}, you can @dfn{mark} the
file with some other character (usually @samp{*}).  Most Dired
commands to operate on files use the files marked with @samp{*}.  The
only command that operates on flagged files is @kbd{x}, which deletes
them.

  Here are some commands for marking with @samp{*}, for unmarking, and
for operating on marks.  (@xref{Dired Deletion}, for commands to flag
and unflag files.)

@table @kbd
@item m
@itemx * m
@kindex m @r{(Dired)}
@kindex * m @r{(Dired)}
@findex dired-mark
Mark the current file with @samp{*} (@code{dired-mark}).  If the
region is active, mark all files in the region instead; otherwise, if
a numeric argument @var{n} is supplied, mark the next @var{n} files
instead, starting with the current file (if @var{n} is negative, mark
the previous @minus{}@var{n} files).  If invoked on a subdirectory
header line (@pxref{Subdirectories in Dired}), this command marks all
the files in that subdirectory.

@item * N
@kindex * N @r{(Dired)}
@findex dired-number-of-marked-files
Report what the number and size of the marked files are
(@code{dired-number-of-marked-files}).

@item * *
@kindex * * @r{(Dired)}
@findex dired-mark-executables
@cindex marking executable files (in Dired)
Mark all executable files with @samp{*}
(@code{dired-mark-executables}).  With a numeric argument, unmark all
those files.

@item * @@
@kindex * @@ @r{(Dired)}
@findex dired-mark-symlinks
@cindex marking symbolic links (in Dired)
Mark all symbolic links with @samp{*} (@code{dired-mark-symlinks}).
With a numeric argument, unmark all those files.

@item * /
@kindex * / @r{(Dired)}
@findex dired-mark-directories
@cindex marking subdirectories (in Dired)
Mark with @samp{*} all files which are directories, except for
@file{.} and @file{..} (@code{dired-mark-directories}).  With a numeric
argument, unmark all those files.

@item * s
@kindex * s @r{(Dired)}
@findex dired-mark-subdir-files
Mark all the files in the current subdirectory, aside from @file{.}
and @file{..} (@code{dired-mark-subdir-files}).

@item u
@itemx * u
@kindex u @r{(Dired)}
@kindex * u @r{(Dired)}
@findex dired-unmark
Remove any mark on this line (@code{dired-unmark}).  If the region is
active, unmark all files in the region instead; otherwise, if a
numeric argument @var{n} is supplied, unmark the next @var{n} files
instead, starting with the current file (if @var{n} is negative,
unmark the previous @minus{}@var{n} files).

@item @key{DEL}
@itemx * @key{DEL}
@kindex * DEL @r{(Dired)}
@findex dired-unmark-backward
@cindex unmarking files (in Dired)
Move point to previous line and remove any mark on that line
(@code{dired-unmark-backward}).  If the region is active, unmark all
files in the region instead; otherwise, if a numeric argument @var{n}
is supplied, unmark the @var{n} preceding files instead, starting with
the current file (if @var{n} is negative, unmark the next
@minus{}@var{n} files).

@item * !
@itemx U
@kindex * ! @r{(Dired)}
@kindex U @r{(Dired)}
@findex dired-unmark-all-marks
Remove all marks from all the files in this Dired buffer
(@code{dired-unmark-all-marks}).

@item * ? @var{markchar}
@itemx M-@key{DEL}
@kindex * ? @r{(Dired)}
@kindex M-DEL @r{(Dired)}
@findex dired-unmark-all-files
Remove all marks that use the character @var{markchar}
(@code{dired-unmark-all-files}).  If invoked with @kbd{M-@key{DEL}},
the command prompts for @var{markchar}.  That @var{markchar} is a
single character---do not use @key{RET} to terminate it.  See the
description of the @kbd{* c} command below, which lets you replace one
mark character with another.

With a numeric argument, this command queries about each marked file,
asking whether to remove its mark.  You can answer @kbd{y} meaning yes,
@kbd{n} meaning no, or @kbd{!} to remove the marks from the remaining
files without asking about them.

@item * C-n
@itemx M-@}
@findex dired-next-marked-file
@kindex * C-n @r{(Dired)}
@kindex M-@} @r{(Dired)}
Move down to the next marked file (@code{dired-next-marked-file}).
A file is ``marked'' if it has any kind of mark.

@item * C-p
@itemx M-@{
@findex dired-prev-marked-file
@kindex * C-p @r{(Dired)}
@kindex M-@{ @r{(Dired)}
Move up to the previous marked file (@code{dired-prev-marked-file}).

@item t
@itemx * t
@kindex t @r{(Dired)}
@kindex * t @r{(Dired)}
@findex dired-toggle-marks
@cindex toggling marks (in Dired)
Toggle all marks (@code{dired-toggle-marks}): files marked with @samp{*}
become unmarked, and unmarked files are marked with @samp{*}.  Files
marked in any other way are not affected.

@item * c @var{old-markchar} @var{new-markchar}
@kindex * c @r{(Dired)}
@findex dired-change-marks
Replace all marks that use the character @var{old-markchar} with marks
that use the character @var{new-markchar} (@code{dired-change-marks}).
This command is the primary way to create or use marks other than
@samp{*} or @samp{D}.  The arguments are single characters---do not use
@key{RET} to terminate them.

You can use almost any character as a mark character by means of this
command, to distinguish various classes of files.  If @var{old-markchar}
is a space (@samp{ }), then the command operates on all unmarked files;
if @var{new-markchar} is a space, then the command unmarks the files it
acts on.

To illustrate the power of this command, here is how to put @samp{D}
flags on all the files that have no marks, while unflagging all those
that already have @samp{D} flags:

@example
* c D t  * c @key{SPC} D  * c t @key{SPC}
@end example

This assumes that no files were already marked with @samp{t}.

@item % m @var{regexp} @key{RET}
@itemx * % @var{regexp} @key{RET}
@findex dired-mark-files-regexp
@kindex % m @r{(Dired)}
@kindex * % @r{(Dired)}
Mark (with @samp{*}) all files whose names match the regular expression
@var{regexp} (@code{dired-mark-files-regexp}).  This command is like
@kbd{% d}, except that it marks files with @samp{*} instead of flagging
with @samp{D}.

Only the non-directory part of the file name is used in matching.  Use
@samp{^} and @samp{$} to anchor matches.  You can exclude
subdirectories by temporarily hiding them (@pxref{Hiding
Subdirectories}).

@item % g @var{regexp} @key{RET}
@findex dired-mark-files-containing-regexp
@kindex % g @r{(Dired)}
@cindex finding files containing regexp matches (in Dired)
Mark (with @samp{*}) all files whose @emph{contents} contain a match for
the regular expression @var{regexp}
(@code{dired-mark-files-containing-regexp}).  This command is like
@kbd{% m}, except that it searches the file contents instead of the file
name.  Note that if a file is visited in an Emacs buffer,
and @code{dired-always-read-filesystem} is @code{nil} (the default), this
command will look in the buffer without revisiting the file, so the results
might be inconsistent with the file on disk if its contents have changed
since it was last visited.  If you don't want this, you may wish to
revert the files you have visited in your buffers, or to turn on
Auto-Revert mode in those buffers, before invoking this command.
@xref{Reverting}.  If you prefer that this command should always
revisit the file, without you having to revert the file or enable
Auto-Revert mode, you might want to set
@code{dired-always-read-filesystem} to non-@code{nil}.

@item C-/
@itemx C-x u
@itemx C-_
@kindex C-_ @r{(Dired)}
@findex dired-undo
Undo changes in the Dired buffer, such as adding or removing
marks (@code{dired-undo}).  @emph{This command does not revert the
actual file operations, nor recover lost files!}  It just undoes
changes in the buffer itself.

In some cases, using this after commands that operate on files can
cause trouble.  For example, after renaming one or more files,
@code{dired-undo} restores the original names in the Dired buffer,
which gets the Dired buffer out of sync with the actual contents of
the directory.

@item touchscreen-hold
@kindex touchscreen-hold @r{(Dired)}
@findex dired-click-to-select-mode
@findex dired-enable-click-to-select-mode
Enter a ``click to select'' mode (@code{dired-click-to-select-mode}),
where using the mouse button @kbd{mouse-2} on a file name will cause its
mark to be toggled.  This mode is useful when performing file management
using a touch screen device.

It is enabled when a ``hold'' gesture (@pxref{Touchscreens}) is detected
over a file name, and is automatically disabled once a Dired command
that operates on the marked files finishes.
@end table

@node Operating on Files
@section Operating on Files
@cindex operating on files in Dired

  This section describes the basic Dired commands to operate on one file
or several files.  All of these commands are capital letters; all of
them use the minibuffer, either to read an argument or to ask for
confirmation, before they act.  All of them let you specify the
files to manipulate in these ways:

@itemize @bullet
@item
If you give the command a numeric prefix argument @var{n}, it operates
on the next @var{n} files, starting with the current file.  (If @var{n}
is negative, the command operates on the @minus{}@var{n} files preceding
the current line.)

@item
Otherwise, if some files are marked with @samp{*}, the command operates
on all those files.

@item
Otherwise, the command operates on the current file only.
@end itemize

@noindent
Certain other Dired commands, such as @kbd{!} and the @samp{%}
commands, use the same conventions to decide which files to work on.

  In addition to Dired commands described here, you can also invoke
Version Control (VC) commands on one or more files shown in a Dired
buffer.  @xref{Version Control}.

@vindex dired-dwim-target
@cindex two directories (in Dired)
  Commands which ask for a destination directory, such as those which
copy and rename files or create links for them, try to guess the default
target directory for the operation.  Normally, they suggest the Dired
buffer's default directory, but if the option @code{dired-dwim-target}
is non-@code{nil}, and if there is another Dired buffer displayed in
some window, that other buffer's directory is suggested instead.
You can customize @code{dired-dwim-target} to prefer either the next
window with a Dired buffer, or the most recently used window with
a Dired buffer, or to use any other function.  When the value is
a function, it will be called with no arguments and is expected to
return a list of directories which will be used as defaults
(i.e., default target and ``future history'').

  Here are the file-manipulating Dired commands that operate on files.

@table @kbd
@findex dired-do-copy
@kindex C @r{(Dired)}
@cindex copying files (in Dired)
@item C @var{new} @key{RET}
Copy the specified files (@code{dired-do-copy}).  The argument @var{new}
is the directory to copy into, or (if copying a single file) the new
name.  This is like the shell command @code{cp}.

@vindex dired-create-destination-dirs
The option @code{dired-create-destination-dirs} controls whether Dired
should create non-existent directories in the destination while
copying/renaming files.  The default value @code{nil} means Dired
never creates such missing directories;  the value @code{always},
means Dired automatically creates them; the value @code{ask}
means Dired asks you for confirmation before creating them.

@vindex dired-create-destination-dirs-on-trailing-dirsep
If the option @code{dired-create-destination-dirs-on-trailing-dirsep}
is non-@code{nil} in addition to @code{dired-create-destination-dirs},
a trailing directory separator at the destination directory is treated
specially.  In that case, when copying to @samp{test/} and no
directory @samp{test} exists already, it will be created and the
specified source files or directories are copied into the newly
created directory.

@vindex dired-copy-preserve-time
If @code{dired-copy-preserve-time} is non-@code{nil}, then copying
with this command preserves the modification time of the old file in
the copy, like @samp{cp -p}.

@vindex dired-recursive-copies
@cindex recursive copying
The variable @code{dired-recursive-copies} controls whether to copy
directories recursively (like @samp{cp -r}).  The default is
@code{top}, which means to ask before recursively copying a directory.

@vindex dired-copy-dereference
@cindex follow symbolic links
@cindex dereference symbolic links
The variable @code{dired-copy-dereference} controls whether to copy
symbolic links as links or after dereferencing (like @samp{cp -L}).
The default is @code{nil}, which means that the symbolic links are
copied by creating new ones.

@vindex dired-keep-marker-copy
The @code{dired-keep-marker-copy} user option controls how this
command handles file marking.  The default is to mark all new copies
of files with a @samp{C} mark.

@findex dired-do-delete
@kindex D @r{(Dired)}
@item D
Delete the specified files (@code{dired-do-delete}).  This is like the
shell command @code{rm}.

Like the other commands in this section, this command operates on the
@emph{marked} files, or the next @var{n} files.  By contrast, @kbd{x}
(@code{dired-do-flagged-delete}) deletes all @dfn{flagged} files.

@findex dired-do-open
@kindex E @r{(Dired)}
@item E
``Open'' the specified files using an external program (@code{dired-do-open}).
The program is selected according to the system conventions, as
determined by the variable @code{shell-command-guess-open}.

@findex dired-do-rename
@kindex R @r{(Dired)}
@cindex renaming files (in Dired)
@cindex moving files (in Dired)
@item R @var{new} @key{RET}
Rename the specified files (@code{dired-do-rename}).  If you rename a
single file, the argument @var{new} is the new name of the file.  If
you rename several files, the argument @var{new} is the directory into
which to move the files (this is like the shell command @command{mv}).

The option @code{dired-create-destination-dirs} controls whether Dired
should create non-existent directories in @var{new}.

The option @code{dired-create-destination-dirs-on-trailing-dirsep},
when set in addition to @code{dired-create-destination-dirs}, controls
whether a trailing directory separator at the destination is treated
specially.  In that case, when renaming a directory @samp{old} to
@samp{new/} and no directory @samp{new} exists already, it will be
created and @samp{old} is moved into the newly created directory.
Otherwise, @samp{old} is renamed to @samp{new}.

Dired automatically changes the visited file name of buffers associated
with renamed files so that they refer to the new names.

@vindex dired-vc-rename-file
If the value of the variable @code{dired-vc-rename-file} is non-@code{nil},
files are renamed using the commands of the underlying VCS, via
@ifnottex
@code{vc-rename-file} (@pxref{VC Delete/Rename}).
@end ifnottex
@iftex
@code{vc-rename-file} (@pxref{VC Delete/Rename,, Deleting and Renaming
Version-Controlled Files, emacs-xtra, Specialized Emacs Features}).
@end iftex

@findex dired-do-hardlink
@kindex H @r{(Dired)}
@cindex hard links (in Dired)
@item H @var{new} @key{RET}
Make hard links to the specified files (@code{dired-do-hardlink}).
This is like the shell command @command{ln}.  The argument @var{new} is
the directory to make the links in, or (if making just one link) the
name to give the link.

@findex dired-do-symlink
@kindex S @r{(Dired)}
@cindex symbolic links (creation in Dired)
@item S @var{new} @key{RET}
Make symbolic links to the specified files (@code{dired-do-symlink}).
This is like @samp{ln -s}.  The argument @var{new} is the directory to
make the links in, or (if making just one link) the name to give the
link.

@findex dired-do-relsymlink
@kindex Y @r{(Dired)}
@item Y @var{new} @key{RET}
Make relative symbolic links to the specified files
(@code{dired-do-relsymlink}).  The argument @var{new} is the directory
to make the links in, or (if making just one link) the name to give
the link.  This is like @code{dired-do-symlink} but creates relative
symbolic links.  For example:

@example
    foo -> ../bar/foo
@end example

@noindent
It does not create absolute ones like:

@example
    foo -> /path/that/may/change/any/day/bar/foo
@end example

@findex dired-do-chmod
@kindex M @r{(Dired)}
@cindex changing file permissions (in Dired)
@item M @var{modespec} @key{RET}
Change the mode (also called @dfn{permission bits}) of the specified
files (@code{dired-do-chmod}).  @var{modespec} can be in octal or
symbolic notation, like arguments handled by the @command{chmod}
program.  This command does not follow symbolic links, so it reports
an error if you try to change the mode of a symbolic link on a
platform where such modes are immutable.

@findex dired-do-chgrp
@kindex G @r{(Dired)}
@cindex changing file group (in Dired)
@item G @var{newgroup} @key{RET}
Change the group of the specified files to @var{newgroup}
(@code{dired-do-chgrp}).

@findex dired-do-chown
@kindex O @r{(Dired)}
@cindex changing file owner (in Dired)
@item O @var{newowner} @key{RET}
Change the owner of the specified files to @var{newowner}
(@code{dired-do-chown}).  (On most systems, only the superuser can do
this.)

@vindex dired-chown-program
The variable @code{dired-chown-program} specifies the name of the
program to use to do the work.  (This variable is necessary because
different systems put @command{chown} in different places).

@findex dired-do-touch
@kindex T @r{(Dired)}
@cindex changing file time (in Dired)
@item T @var{timestamp} @key{RET}
Touch the specified files (@code{dired-do-touch}).  This means
updating their modification times to @var{timestamp}, which defaults
to the present time.  This is like the shell command @command{touch}.

@findex dired-do-print
@kindex P @r{(Dired)}
@cindex printing files (in Dired)
@item P @var{command} @key{RET}
Print the specified files (@code{dired-do-print}).  You must specify the
command to print them with, but the minibuffer starts out with a
suitable guess made using the variables @code{lpr-command} and
@code{lpr-switches} (the same variables that @code{lpr-buffer} uses;
@pxref{Printing}).

@findex dired-do-compress
@kindex Z @r{(Dired)}
@cindex compressing files (in Dired)
@item Z
Compress the specified files (@code{dired-do-compress}).  If the file
appears to be a compressed file already, uncompress it instead.  Each
marked file is compressed into its own archive; this uses the
@command{gzip} program if it is available, otherwise it uses
@command{compress}.

On a directory name, this command produces a compressed archive
depending on the @code{dired-compress-directory-default-suffix} user
option.  The default is a @file{.tar.gz} archive containing all of the
directory's files, by running the @command{tar} command with output
piped to @command{gzip}.  To allow decompression of compressed
directories, typing @kbd{Z} on a @file{.tar.gz} or @file{.tgz} archive
file unpacks all the files in the archive into a directory whose name
is the archive name with the extension removed.

@findex dired-do-compress-to
@kindex c @r{(Dired)}
@item c
Compress the specified files (@code{dired-do-compress-to}) into a
single archive anywhere on the file system.  The default archive is
controlled by the @code{dired-compress-directory-default-suffix} user
option.  Also see @code{dired-compress-files-alist}.

@findex epa-dired-do-decrypt
@kindex :d @r{(Dired)}
@cindex decrypting files (in Dired)
@item :d
Decrypt the specified files (@code{epa-dired-do-decrypt}).
@xref{Dired integration,,, epa, EasyPG Assistant User's Manual}.

@findex epa-dired-do-verify
@kindex :v @r{(Dired)}
@cindex verifying digital signatures on files (in Dired)
@item :v
Verify digital signatures on the specified files (@code{epa-dired-do-verify}).
@xref{Dired integration,,, epa, EasyPG Assistant User's Manual}.

@findex epa-dired-do-sign
@kindex :s @r{(Dired)}
@cindex signing files (in Dired)
@item :s
Digitally sign the specified files (@code{epa-dired-do-sign}).
@xref{Dired integration,,, epa, EasyPG Assistant User's Manual}.

@findex epa-dired-do-encrypt
@kindex :e @r{(Dired)}
@cindex encrypting files (in Dired)
@item :e
Encrypt the specified files (@code{epa-dired-do-encrypt}).
@xref{Dired integration,,, epa, EasyPG Assistant User's Manual}.

@findex dired-do-load
@kindex L @r{(Dired)}
@cindex loading several files (in Dired)
@item L
Load the specified Emacs Lisp files (@code{dired-do-load}).
@xref{Lisp Libraries}.

@findex dired-do-byte-compile
@kindex B @r{(Dired)}
@cindex byte-compiling several files (in Dired)
@item B
Byte compile the specified Emacs Lisp files
(@code{dired-do-byte-compile}).  @xref{Byte Compilation,, Byte
Compilation, elisp, The Emacs Lisp Reference Manual}.

@findex dired-do-info
@kindex I @r{(Dired)}
@cindex running info on files (in Dired)
@item I
Run Info on this file (assumed to be a file in Info format).

@findex dired-do-man
@kindex N @r{(Dired)}
@cindex running man on files (in Dired)
@item N
Run man on this file (assumed to be a file in @code{nroff} format).

@kindex A @r{(Dired)}
@findex dired-do-find-regexp
@cindex search multiple files (in Dired)
@item A @var{regexp} @key{RET}
Search all the specified files for the regular expression @var{regexp}
(@code{dired-do-find-regexp}).

This command is a variant of @code{xref-find-references}
(@pxref{Identifier Search}), it displays the @file{*xref*} buffer,
where you can navigate between matches and display them as needed
using the commands described in @ref{Xref Commands}.

@vindex grep-find-ignored-files @r{(Dired)}
@vindex grep-find-ignored-directories @r{(Dired)}
If any of the marked files are directories, then this command searches
all of the files in those directories, and any of their
subdirectories, recursively, except files whose names match
@code{grep-find-ignored-files} and subdirectories whose names match
@code{grep-find-ignored-directories}.

@kindex Q @r{(Dired)}
@findex dired-do-find-regexp-and-replace
@cindex search and replace in multiple files (in Dired)
@item Q @var{regexp} @key{RET} @var{to} @key{RET}
Perform @code{query-replace-regexp} on each of the specified files,
replacing matches for @var{regexp} with the string
@var{to} (@code{dired-do-find-regexp-and-replace}).

This command is a variant of @code{xref-query-replace-in-results}.  It
presents an @file{*xref*} buffer that lists all the matches of @var{regexp},
and you can use the special commands in that buffer (@pxref{Xref
Commands}).  In particular, if you exit the query replace loop, you
can use @kbd{r} in that buffer to replace more matches.
@xref{Identifier Search}.

Like with @code{dired-do-find-regexp}, if any of the marked files are
directories, this command performs replacements in all of the files in
those directories, and in any of their subdirectories, recursively,
except for files whose names match @code{grep-find-ignored-files} and
subdirectories whose names match @code{grep-find-ignored-directories}.
@end table

@node Shell Commands in Dired
@section Shell Commands in Dired
@cindex shell commands, Dired

@findex dired-do-shell-command
@kindex ! @r{(Dired)}
@kindex X @r{(Dired)}
@vindex dired-confirm-shell-command
The Dired command @kbd{!} (@code{dired-do-shell-command}) reads a
shell command string in the minibuffer, and runs that shell command on
one or more files.  The files that the shell command operates on are
determined in the usual way for Dired commands (@pxref{Operating on
Files}).  The command @kbd{X} is a synonym for @kbd{!}.

  The command @kbd{&} (@code{dired-do-async-shell-command}) does the
same, except that it runs the shell command asynchronously.  (You can
also do this with @kbd{!}, by appending a @samp{&} character to the
end of the shell command.)  When the command operates on more than one
file, it runs multiple parallel copies of the specified shell command,
one for each file.  As an exception, if the specified shell command
ends in @samp{;} or @samp{;&}, the shell command is run in the
background on each file sequentially; Emacs waits for each invoked
shell command to terminate before running the next one.

  For both @kbd{!} and @kbd{&}, the working directory for the shell
command is the top-level directory of the Dired buffer.

  If you tell @kbd{!} or @kbd{&} to operate on more than one file, the
shell command string determines how those files are passed to the
shell command:

@itemize @bullet
@item
If you use @samp{*} surrounded by whitespace in the command string,
then the command runs just once, with the list of file names
substituted for the @samp{*}.  The order of file names is the order of
appearance in the Dired buffer.

Thus, @kbd{! tar cf foo.tar * @key{RET}} runs @code{tar} on the entire
list of file names, putting them into one tar file @file{foo.tar}.

If you want to use @samp{*} as a shell wildcard with whitespace around
it, write @samp{*""}.  In the shell, this is equivalent to @samp{*};
but since the @samp{*} is not surrounded by whitespace, Dired does not
treat it specially.  Emacs will prompt for confirmation if you do
this, unless @code{dired-confirm-shell-command} is @code{nil}.

@item
Otherwise, if the command string contains @samp{?} surrounded by
whitespace or @samp{`?`}, Emacs runs the shell command once
@emph{for each file}, substituting the current file name for @samp{?}
and @samp{`?`} each time.  You can use both @samp{?} and @samp{`?`} more
than once in the command; the same file name replaces each occurrence.
If you mix them with @samp{*} the command signals an error.

@item
If the command string contains neither @samp{*} nor @samp{?} nor @samp{`?`},
Emacs runs the shell command once for each file, adding the file name at the
end.  For example, @kbd{! uudecode @key{RET}} runs @code{uudecode} on
each file.
@end itemize

  To iterate over the file names in a more complicated fashion, you might
prefer to use an explicit shell loop.  For example, here is how to uuencode
each file, making the output file name by appending @samp{.uu} to the input
file name:

@example
for file in * ; do uuencode "$file" "$file" >"$file".uu; done
@end example

The same example with @samp{`?`} notation:
@example
uuencode ? ? > `?`.uu
@end example

  The @kbd{!} and @kbd{&} commands do not attempt to update the Dired
buffer to show new or modified files, because they don't know what
files will be changed.  Use the @kbd{g} command to update the Dired
buffer (@pxref{Dired Updating}).

  @xref{Single Shell}, for information about running shell commands
outside Dired.

@node Shell Command Guessing
@section Shell Command Guessing
@cindex guessing shell commands for files (in Dired)

Based upon the name of a file, Dired tries to guess what shell command
you might want to apply to it.  For example, if you have point on a
file named @file{foo.tar} and you press @kbd{!}, Dired will guess that
you want to run @samp{tar xvf}, and suggest that as the default shell
command.

You can type @kbd{M-n} to get the default into the minibuffer for
editing.  If there are several commands for a given file, type
@kbd{M-n} several times to see each matching command in order.

Dired only tries to guess a command for a single file, never for a
list of marked files.

@defvar dired-guess-shell-alist-default
This variable specifies the predefined rules for guessing shell
commands suitable for certain files.  Set this to @code{nil} to turn
guessing off.  The elements of @code{dired-guess-shell-alist-user}
(defined by the user) will override these rules.
@end defvar

@defvar dired-guess-shell-alist-optional
This variable is like @code{dired-guess-shell-alist-default} but
contains external viewers and players for various media formats.
Setting this to @code{nil} turns guessing off.  The variables
@code{dired-guess-shell-alist-user} and
@code{dired-guess-shell-alist-default} will override these rules.
@end defvar

@defvar dired-guess-shell-alist-user
If non-@code{nil}, this variable specifies the user-defined alist of
file regexps and their suggested commands.  These rules take
precedence over the predefined rules in the variables
@code{dired-guess-shell-alist-default} and
@code{dired-guess-shell-alist-optional} when
@code{dired-do-shell-command} is run).  The default is @code{nil}.

Each element of the alist looks like

@example
(@var{regexp} @var{command}@dots{})
@end example

@noindent
where each @var{command} can either be a string or a Lisp expression
that evaluates to a string.  If several commands are given, all of
them will temporarily be pushed onto the history.

A @samp{*} in the shell command stands for the file name that matched
@var{regexp}.  When Emacs invokes the @var{command}, it replaces each
instance of @samp{*} with the matched file name.

To add rules for @samp{.foo} and @samp{.bar} file extensions, add this
to your Init file:

@example
(setq dired-guess-shell-alist-user
      (list
       (list "\\.foo$" "@var{foo-command}")  ; fixed rule
       ;; possibly more rules...
       (list "\\.bar$"  ; rule with condition test
             '(if @var{condition}
                  "@var{bar-command-1}"
                "@var{bar-command-2}"))))
@end example

@noindent
This will override any predefined rules for the same extensions.
@end defvar

You can find more user options with @kbd{M-x customize-group @key{RET}
dired-guess @key{RET}}.

@node Transforming File Names
@section Transforming File Names in Dired

  This section describes Dired commands which alter file names in a
systematic way.  Each command operates on some or all of the marked
files, using a new name made by transforming the existing name.

  Like the basic Dired file-manipulation commands (@pxref{Operating on
Files}), the commands described here operate either on the next
@var{n} files, or on all files marked with @samp{*}, or on the current
file.  (To mark files, use the commands described in @ref{Marks vs
Flags}.)

  All of the commands described in this section work
@emph{interactively}: they ask you to confirm the operation for each
candidate file.  Thus, you can select more files than you actually
need to operate on (e.g., with a regexp that matches many files), and
then filter the selected names by typing @kbd{y} or @kbd{n} when the
command prompts for confirmation.

@table @kbd
@findex dired-upcase
@kindex % u @r{(Dired)}
@cindex upcase file names
@item % u
Rename each of the selected files to an upper-case name
(@code{dired-upcase}).  If the old file names are @file{Foo}
and @file{bar}, the new names are @file{FOO} and @file{BAR}.

@item % l
@findex dired-downcase
@kindex % l @r{(Dired)}
@cindex downcase file names
Rename each of the selected files to a lower-case name
(@code{dired-downcase}).  If the old file names are @file{Foo} and
@file{bar}, the new names are @file{foo} and @file{bar}.

@item % R @var{from} @key{RET} @var{to} @key{RET}
@kindex % R @r{(Dired)}
@findex dired-do-rename-regexp
@itemx % C @var{from} @key{RET} @var{to} @key{RET}
@kindex % C @r{(Dired)}
@findex dired-do-copy-regexp
@itemx % H @var{from} @key{RET} @var{to} @key{RET}
@kindex % H @r{(Dired)}
@findex dired-do-hardlink-regexp
@itemx % S @var{from} @key{RET} @var{to} @key{RET}
@kindex % S @r{(Dired)}
@findex dired-do-symlink-regexp
@itemx % Y @var{from} @key{RET} @var{to} @key{RET}
@kindex % Y @r{(Dired)}
@findex dired-do-relsymlink-regexp
These five commands rename, copy, make hard links, make soft links,
and make relative soft links, in each case computing the new name by
regular-expression substitution from the name of the old file.
@end table

  The four regular-expression substitution commands effectively
perform a search-and-replace on the selected file names.  They read
two arguments: a regular expression @var{from}, and a substitution
pattern @var{to}; they match each old file name against
@var{from}, and then replace the matching part with @var{to}.  You can
use @samp{\&} and @samp{\@var{digit}} in @var{to} to refer to all or
part of what the pattern matched in the old file name, as in
@code{replace-regexp} (@pxref{Regexp Replace}).  If the regular
expression matches more than once in a file name, only the first match
is replaced.

  For example, @kbd{% R ^.*$ @key{RET} x-\& @key{RET}} renames each
selected file by prepending @samp{x-} to its name.  The inverse of this,
removing @samp{x-} from the front of each file name, is also possible:
one method is @kbd{% R ^x-\(.*\)$ @key{RET} \1 @key{RET}}; another is
@kbd{% R ^x- @key{RET} @key{RET}}.  (Use @samp{^} and @samp{$} to anchor
matches that should span the whole file name.)

  Normally, the replacement process does not consider the files'
directory names; it operates on the file name within the directory.  If
you specify a numeric argument of zero, then replacement affects the
entire absolute file name including directory name.  (A non-zero
argument specifies the number of files to operate on.)

  You may want to select the set of files to operate on using the same
regexp @var{from} that you will use to operate on them.  To do this,
mark those files with @kbd{% m @var{from} @key{RET}}, then use the
same regular expression in the command to operate on the files.  To
make this more convenient, the @kbd{%} commands to operate on files
use the last regular expression specified in any @kbd{%} command as a
default.

@node Comparison in Dired
@section File Comparison with Dired
@cindex file comparison (in Dired)
@cindex compare files (in Dired)

@findex dired-diff
@kindex = @r{(Dired)}
  The @kbd{=} (@code{dired-diff}) command compares the current file
(the file at point) with another file (read using the minibuffer)
using the @command{diff} program.  The file specified with the
minibuffer is the first argument of @command{diff}, and file at point
is the second argument.  The output of the @command{diff} program is
shown in a buffer using Diff mode (@pxref{Comparing Files}).

  If the region is active, the default for the file read using the
minibuffer is the file at the mark (i.e., the ordinary Emacs mark,
not a Dired mark; @pxref{Setting Mark}).  Otherwise, if the file at
point has a backup file (@pxref{Backup}), that is the default.

  You could also compare files using @code{ediff-files}, see
@ref{Major Entry Points,,, ediff, Ediff User's Manual}.

@node Subdirectories in Dired
@section Subdirectories in Dired
@cindex subdirectories in Dired
@cindex expanding subdirectories in Dired

  A Dired buffer usually displays just one directory, but you can
optionally include its subdirectories as well.

  The simplest way to include multiple directories in one Dired buffer is
to specify the options @samp{-lR} for running @command{ls}.  (If you give a
numeric argument when you run Dired, then you can specify these options
in the minibuffer.)  That produces a recursive directory listing showing
all subdirectories at all levels.

  More often, you will want to show only specific subdirectories.  You
can do this with @kbd{i} (@code{dired-maybe-insert-subdir}):

@table @kbd
@findex dired-maybe-insert-subdir
@kindex i @r{(Dired)}
@item i
@cindex inserted subdirectory (Dired)
@cindex in-situ subdirectory (Dired)
Insert the contents of a subdirectory later in the buffer.
@end table

@noindent
If you use this command on a line that describes a file which is a
directory, it inserts the contents of that directory into the same
Dired buffer, and moves there.  Inserted subdirectory contents follow
the top-level directory of the Dired buffer, just as they do in
@samp{ls -lR} output.

  If the subdirectory's contents are already present in the buffer,
the @kbd{i} command just moves to it.

  In either case, @kbd{i} sets the Emacs mark before moving, so
@kbd{C-u C-@key{SPC}} returns to your previous position in the Dired
buffer (@pxref{Setting Mark}).  You can also use @samp{^} to return to
the parent directory in the same Dired buffer (@pxref{Dired
Visiting}).

  Use the @kbd{l} command (@code{dired-do-redisplay}) to update the
subdirectory's contents, and use @kbd{C-u k} on the subdirectory
header line to remove the subdirectory listing (@pxref{Dired
Updating}).  You can also hide and show inserted subdirectories
(@pxref{Hiding Subdirectories}).

@ifnottex
@include dired-xtra.texi
@end ifnottex

@node Subdirectory Motion
@section Moving Over Subdirectories

  When a Dired buffer lists subdirectories, you can use the page motion
commands @kbd{C-x [} and @kbd{C-x ]} to move by entire directories
(@pxref{Pages}).

@cindex header line (Dired)
@cindex directory header lines
  The following commands move across, up and down in the tree of
directories within one Dired buffer.  They move to @dfn{directory header
lines}, which are the lines that give a directory's name, at the
beginning of the directory's contents.

@table @kbd
@findex dired-next-subdir
@kindex C-M-n @r{(Dired)}
@item C-M-n
Go to next subdirectory header line, regardless of level
(@code{dired-next-subdir}).

@findex dired-prev-subdir
@kindex C-M-p @r{(Dired)}
@item C-M-p
Go to previous subdirectory header line, regardless of level
(@code{dired-prev-subdir}).

@findex dired-tree-up
@kindex C-M-u @r{(Dired)}
@item C-M-u
Go up to the parent directory's header line (@code{dired-tree-up}).

@findex dired-tree-down
@kindex C-M-d @r{(Dired)}
@item C-M-d
Go down in the directory tree, to the first subdirectory's header line
(@code{dired-tree-down}).

@findex dired-prev-dirline
@kindex < @r{(Dired)}
@item <
Move up to the previous directory-file line (@code{dired-prev-dirline}).
These lines are the ones that describe a directory as a file in its
parent directory.

@findex dired-next-dirline
@kindex > @r{(Dired)}
@item >
Move down to the next directory-file line (@code{dired-next-dirline}).

@findex dired-goto-subdir
@kindex M-G @r{(Dired)}
@item M-G
Prompt for a directory and move to its directory-file line
(@code{dired-goto-subdir}).
@end table

@node Hiding Subdirectories
@section Hiding Subdirectories
@cindex hiding subdirectories (Dired)
@cindex showing hidden subdirectories (Dired)

  @dfn{Hiding} a subdirectory means to make it invisible, except for its
header line.

@table @kbd
@item $
@findex dired-hide-subdir
@kindex $ @r{(Dired)}
Hide or show the subdirectory that point is in, and move point to the
next subdirectory (@code{dired-hide-subdir}).  This is a toggle.  A
numeric argument serves as a repeat count.

@item M-$
@findex dired-hide-all
@kindex M-$ @r{(Dired)}
Hide all subdirectories in this Dired buffer, leaving only their header
lines (@code{dired-hide-all}).  Or, if any subdirectory is currently
hidden, make all subdirectories visible again.  You can use this command
to get an overview in very deep directory trees or to move quickly to
subdirectories far away.
@end table

  Ordinary Dired commands never consider files inside a hidden
subdirectory.  For example, the commands to operate on marked files
ignore files in hidden directories even if they are marked.  Thus you
can use hiding to temporarily exclude subdirectories from operations
without having to remove the Dired marks on files in those
subdirectories.

@xref{Subdirectories in Dired}, for how to insert a subdirectory
listing, and see @ref{Dired Updating}, for how to delete it.

@node Dired Updating
@section Updating the Dired Buffer
@cindex updating Dired buffer
@cindex refreshing displayed files

  This section describes commands to update the Dired buffer to reflect
outside (non-Dired) changes in the directories and files, and to delete
part of the Dired buffer.

@table @kbd
@item g
Update the entire contents of the Dired buffer (@code{revert-buffer}).

@item l
Update the specified files (@code{dired-do-redisplay}).  You specify the
files for @kbd{l} in the same way as for file operations.

@item k
Delete the specified @emph{file lines}---not the files, just the lines
(@code{dired-do-kill-lines}).

@item s
Toggle between alphabetical order and date/time order
(@code{dired-sort-toggle-or-edit}).

@item C-u s @var{switches} @key{RET}
Refresh the Dired buffer using @var{switches} as
@code{dired-listing-switches}.
@end table

@kindex g @r{(Dired)}
@findex revert-buffer @r{(Dired)}
  Type @kbd{g} (@code{revert-buffer}) to update the contents of the
Dired buffer, based on changes in the files and directories listed.
This preserves all marks except for those on files that have vanished.
Hidden subdirectories are updated but remain hidden.

@kindex l @r{(Dired)}
@findex dired-do-redisplay
  To update only some of the files, type @kbd{l}
(@code{dired-do-redisplay}).  Like the Dired file-operating commands,
this command operates on the next @var{n} files (or previous
@minus{}@var{n} files), or on the marked files if any, or on the
current file.  Updating the files means reading their current status,
then updating their lines in the buffer to indicate that status.

  If you use @kbd{l} on a subdirectory header line, it updates the
contents of the corresponding subdirectory.

@vindex dired-auto-revert-buffer
  If you use @kbd{C-x d} or some other Dired command to visit a
directory that is already being shown in a Dired buffer, Dired
switches to that buffer but does not update it.  If the buffer is not
up-to-date, Dired displays a warning telling you to type @kbd{g} to
update it.  You can also tell Emacs to revert each Dired buffer
automatically when you revisit it, by setting the variable
@code{dired-auto-revert-buffer} to a non-@code{nil} value.

@kindex k @r{(Dired)}
@findex dired-do-kill-lines
  To delete @emph{file lines} from the buffer---without actually
deleting the files---type @kbd{k} (@code{dired-do-kill-lines}).  Like
the file-operating commands, this command operates on the next @var{n}
files, or on the marked files if any.  However, it does not operate on
the current file, since otherwise mistyping @kbd{k} could be annoying.

  If you use @kbd{k} to kill the line for a directory file which you
had inserted in the Dired buffer as a subdirectory
(@pxref{Subdirectories in Dired}), it removes the subdirectory listing
as well.  Typing @kbd{C-u k} on the header line for a subdirectory
also removes the subdirectory line from the Dired buffer.

  The @kbd{g} command brings back any individual lines that you have
killed in this way, but not subdirectories---you must use @kbd{i} to
reinsert a subdirectory.

@cindex Dired sorting
@cindex sorting Dired buffer
@kindex s @r{(Dired)}
@findex dired-sort-toggle-or-edit
  The files in a Dired buffers are normally listed in alphabetical order
by file names.  Alternatively Dired can sort them by date/time.  The
Dired command @kbd{s} (@code{dired-sort-toggle-or-edit}) switches
between these two sorting modes.  The mode line in a Dired buffer
indicates which way it is currently sorted---by name, or by date.

  @kbd{C-u s @var{switches} @key{RET}} lets you specify a new value for
@code{dired-listing-switches}.

@node Dired and Find
@section Dired and @code{find}
@cindex @code{find} and Dired

  You can select a set of files for display in a Dired buffer more
flexibly by using the @command{find} utility to choose the files.

@findex find-name-dired
  To search for files with names matching a wildcard pattern use
@kbd{M-x find-name-dired}.  It reads arguments @var{directory} and
@var{pattern}, and chooses all the files in @var{directory} or its
subdirectories whose individual names match @var{pattern}.

  The files thus chosen are displayed in a Dired buffer, in which the
ordinary Dired commands are available.

@findex find-grep-dired
  If you want to test the contents of files, rather than their names,
use @kbd{M-x find-grep-dired}.  This command reads two minibuffer
arguments, @var{directory} and @var{regexp}; it chooses all the files
in @var{directory} or its subdirectories that contain a match for
@var{regexp}.  It works by running the programs @command{find} and
@command{grep}.  See also @kbd{M-x grep-find}, in @ref{Grep
Searching}.  Remember to write the regular expression for
@command{grep}, not for Emacs.  (An alternative method of showing
files whose contents match a given regexp is the @kbd{% g
@var{regexp}} command, see @ref{Marks vs Flags}.)

@findex find-dired
  The most general command in this series is @kbd{M-x find-dired},
which lets you specify any condition that @command{find} can test.  It
takes two minibuffer arguments, @var{directory} and @var{find-args};
it runs @command{find} in @var{directory}, passing @var{find-args} to
tell @command{find} what condition to test.  To use this command, you
need to know how to use @command{find}.

@vindex find-ls-option
  The format of listing produced by these commands is controlled by
the variable @code{find-ls-option}.  This is a pair of options; the
first specifying how to call @command{find} to produce the file listing,
and the second telling Dired to parse the output.

@findex locate
@findex locate-with-filter
@cindex file database (locate)
@vindex locate-command
  The command @kbd{M-x locate} provides a similar interface to the
@command{locate} program.  @kbd{M-x locate-with-filter} is similar, but
keeps only files whose names match a given regular expression.

  These buffers don't work entirely like ordinary Dired buffers: file
operations work, but do not always automatically update the buffer.
Reverting the buffer with @kbd{g} deletes all inserted subdirectories,
and erases all flags and marks.

@node Wdired
@section Editing the Dired Buffer

@cindex wdired mode
@findex wdired-change-to-wdired-mode
  Wdired is a special mode that allows you to perform file operations
by editing the Dired buffer directly (the ``W'' in ``Wdired'' stands
for ``writable'').  To enter Wdired mode, type @kbd{C-x C-q}
(@code{dired-toggle-read-only}) while in a Dired buffer.
Alternatively, use the @samp{Immediate / Edit File Names} menu item.

@findex wdired-finish-edit
  While in Wdired mode, you can rename files by editing the file names
displayed in the Dired buffer.  All the ordinary Emacs editing
commands, including rectangle operations and @code{query-replace}, are
available for this.  Once you are done editing, type @kbd{C-c C-c}
(@code{wdired-finish-edit}).  This applies your changes and switches
back to ordinary Dired mode.

  Apart from simply renaming files, you can move a file to another
directory by typing in the new file name (either absolute or
relative).  To mark a file for deletion, delete the entire file name.
To change the target of a symbolic link, edit the link target name
which appears next to the link name.

  If you edit the file names to create a new subdirectory, Wdired will
automatically create these new directories.  To inhibit this behavior,
set @code{wdired-create-parent-directories} to @code{nil}.

  The rest of the text in the buffer, such as the file sizes and
modification dates, is marked read-only, so you can't edit it.
However, if you set @code{wdired-allow-to-change-permissions} to
@code{t}, you can edit the file permissions.  For example, you can
change @samp{-rw-r--r--} to @samp{-rw-rw-rw-} to make a file
world-writable.  These changes also take effect when you type @kbd{C-c
C-c}.

@node Image-Dired
@section Viewing Image Thumbnails in Dired
@cindex @code{image-dired} mode
@cindex @code{image-dired}

  Image-Dired is a facility for browsing image files.  It provides viewing
the images either as thumbnails or in full size, either inside Emacs
or through an external viewer.  This is different from Image mode
(@pxref{Image Mode}) for visiting an image file in the Emacs buffer.

@kindex C-t d @r{(Image-Dired)}
@findex image-dired-display-thumbs
  To enter Image-Dired, mark the image files you want to look at in
the Dired buffer, using @kbd{m} as usual.  Then type @kbd{C-t d}
(@code{image-dired-display-thumbs}).  This creates and switches to a
buffer containing Image-Dired, corresponding to the marked files.

  You can also enter Image-Dired directly by typing @kbd{M-x
image-dired}.  This prompts for a directory; specify one that has
image files.  This creates thumbnails for all the images in that
directory, and displays them all in the thumbnail buffer.  The
thumbnails are generated in the background and are loaded as they
become available.

@vindex image-dired-thumbnail-storage
  Image-Dired supports three methods of generating and storing
thumbnails, controlled by the value of the option
@code{image-dired-thumbnail-storage}:

@table @code
@vindex image-dired-dir
@vindex image-dired-thumb-naming
@item image-dired
This method stores thumbnails as JPEG images in a single directory
specified by the variable @code{image-dired-dir}.  This is the default.
The names of the thumbnail files are in this case constructed according
to the value of @code{image-dired-thumb-naming}.
@item standard
@itemx standard-large
@itemx standard-x-large
@itemx standard-xx-large
These methods, mandated by the
@url{https://specifications.freedesktop.org/thumbnail-spec/thumbnail-spec-latest.html,
Thumbnail Managing Standard}, store thumbnails as @acronym{PNG} images
under the @file{thumbnails} subdirectory of the directory specified by
the environment variable @env{XDG_CACHE_HOME} (which defaults to
@file{~/.cache}).
@item per-directory
This method stores the thumbnails of each directory in a
@file{.image-dired} subdirectory of that directory, as @acronym{jpeg}
images.
@end table

@vindex image-dired-thumb-size
  You can control the size of the thumbnail images by customizing the
variable @code{image-dired-thumb-size}.  The default is 128 pixels.
This variable is in effect only for the first and the third method of
thumbnail storage described above; the Thumbnail Managing Standard uses
fixed sizes determined by the method: @code{standard} uses 128 pixels,
@code{standard-large} 256 pixels, etc.  If you change the size after
some thumbnails were already created, you need to erase the thumbnail
files from their directory to have the new size take effect.

@findex image-dired-display-this
@findex image-dired-display-next
@findex image-dired-display-previous
  With point in the thumbnail buffer, you can type @key{RET}
(@code{image-dired-display-this}) to display the image in another
window.  Use the standard Emacs movement key bindings or the arrow
keys to move around in the thumbnail buffer.  For easy browsing, use
@key{SPC} (@code{image-dired-display-next}) to advance and display the
next image.  Typing @key{DEL} (@code{image-dired-display-previous})
backs up to the previous thumbnail and displays that instead.

@vindex image-dired-external-viewer
  Type @kbd{C-@key{RET}}
(@code{image-dired-thumbnail-display-external}) to display the image
in an external viewer.  You must first configure
@code{image-dired-external-viewer}.

  You can delete images through Image-Dired also.  Type @kbd{d}
(@code{image-dired-flag-thumb-original-file}) to flag the image file
for deletion in the Dired buffer.  Alternatively, you can remove an
image's thumbnail from the thumbnail buffer without flagging the image
for deletion, by typing @kbd{C-d} (@code{image-dired-delete-char}).

@findex image-dired-dired-toggle-marked-thumbs
@findex image-dired-dired-display-external
@findex image-dired-dired-display-image
  You could also use Image-Dired for ``inline'' operations (i.e.,
right into the Dired buffer).  Type @kbd{C-t C-t}, and the thumbnails
of the selected images in Dired will appear in front of their names
(@code{image-dired-dired-toggle-marked-thumbs}).  @kbd{C-t i} and
@kbd{C-t x} will display the image under the point in Emacs or with
the external viewer, respectively.

  More advanced features include @dfn{image tags}, which are metadata
used to categorize image files.  The tags are stored in a plain text
file configured by @code{image-dired-tags-db-file}.

  To tag image files, mark them in the Dired buffer (you can also mark
files in Dired from the thumbnail buffer by typing @kbd{m}) and type
@kbd{C-t t} (@code{image-dired-tag-files}).  This reads the tag name
in the minibuffer.  To mark files having a certain tag, type @kbd{C-t f}
(@code{image-dired-mark-tagged-files}).  After marking image files
with a certain tag, you can use @kbd{C-t d} to view them.

@findex image-dired-dired-comment-files
@findex image-dired-dired-edit-comment-and-tags
  You can also tag a file directly from the thumbnail buffer by typing
@kbd{t t}, and you can remove a tag by typing @kbd{t r}.  There is
also a special tag called ``comment'' for each file (it is not a tag
in the exact same sense as the other tags, it is handled slightly
differently).  That is used to enter a comment or description about
the image.  You comment a file from the thumbnail buffer by typing
@kbd{c}.  You will be prompted for a comment.  Type @kbd{C-t c} to add
a comment from Dired (@code{image-dired-dired-comment-files}).
@kbd{C-t e} will bring a buffer to edit comment and tags
(@code{image-dired-dired-edit-comment-and-tags}).

@findex image-dired-thumbnail-set-image-description
  If you have the @command{exiftool} program installed, you can set the
@acronym{EXIF} @samp{ImageDescription} tag of an image file by invoking
the @code{image-dired-thumbnail-set-image-description} command with
point at the thumbnail of the image file.  This command prompts for the
description of the image, and adds the @acronym{EXIF} tag to it.

@vindex image-dired-thumb-visible-marks
  Files that are marked in Dired will also be marked in Image-Dired if
@code{image-dired-thumb-visible-marks} is non-@code{nil} (which is the
default).

  Image-Dired also provides simple image manipulation.  In the
thumbnail buffer, type @kbd{L} to rotate the original image 90 degrees
anti clockwise, and @kbd{R} to rotate it 90 degrees clockwise.  This
rotation is lossless, and uses an external utility called
@command{jpegtran}, which you need to install first.

@node Misc Dired Features
@section Other Dired Features

@vindex dired-free-space
  By default, Dired displays the available space on the directory's
disk on the first line of that directory's listing, following the
directory name.  You can control this display by customizing the
variable @code{dired-free-space}.  Its default value is @code{first},
which produces the available space after the directory name.  If you
customize it to the value @code{separate} instead, Dired will display
the disk space information on a separate line, following the line with
the directory name, and will include in that line the space used by
the files in the current directory as well as the available disk
space.  If you set this to @code{nil}, the available disk space
information will not be displayed at all.

@vindex dired-check-symlinks
  Dired fontifies the items in the Dired buffer.  If the
@code{default-directory} of that buffer is remote, this might be
expensive for symbolic links, because their @code{file-truename} needs
to be accessed.  To avoid slowdown in Dired due to this, set user option
@code{dired-check-symlinks} to @code{nil} for remote directories which
suffer from a slow connection.  It can be declared as connection-local
variable to match how a remote system is connectable (@pxref{Connection
Variables}).

@kindex + @r{(Dired)}
@findex dired-create-directory
  The command @kbd{+} (@code{dired-create-directory}) reads a
directory's name, and creates that directory.  It signals an error if
the directory already exists.

@findex dired-create-empty-file
  The command (@code{dired-create-empty-file}) reads a
file name, and creates that file.  It signals an error if
the file already exists.

@cindex searching multiple files via Dired
@kindex M-s a C-s @r{(Dired)}
@kindex M-s a M-C-s @r{(Dired)}
@findex dired-do-isearch
@findex dired-do-isearch-regexp
  The command @kbd{M-s a C-s} (@code{dired-do-isearch}) begins a
multi-file incremental search on the marked files.  If a search
fails at the end of a file, typing @kbd{C-s} advances to the next
marked file and repeats the search; at the end of the last marked
file, the search wraps around to the first marked file.  The command
@kbd{M-s a M-C-s} (@code{dired-do-isearch-regexp}) does the same with
a regular expression search.  @xref{Repeat Isearch}, for information
about search repetition.

@cindex adding to the kill ring in Dired
@kindex w @r{(Dired)}
@findex dired-copy-filename-as-kill
  The command @kbd{w} (@code{dired-copy-filename-as-kill}) puts the
names of the marked (or next @var{n}) files into the kill ring, as if
you had killed them with @kbd{C-w}.  The names are separated by a
space.

  With a zero prefix argument, this uses the absolute file name of each
marked file.  With prefix value 1, it uses names relative to the
project root.  With just @kbd{C-u} as the prefix argument, it uses
file names relative to the Dired buffer's default directory.  (This
can still contain slashes if in a subdirectory.)  As a special case,
if point is on a directory header line, @kbd{w} gives you the absolute
name of that directory.  Any prefix argument or marked files are
ignored in this case.

  The main purpose of this command is so that you can yank the file
names into arguments for other Emacs commands.  It also displays what
it added to the kill ring, so you can use it to display the list of
currently marked files in the echo area.

@kindex W @r{(Dired)}
@findex browse-url-of-dired-file
  If you have an HTML file in the file listing, it can be useful to
view that file with a browser.  The @kbd{W}
(@code{browse-url-of-dired-file}) command will use the standard
configured browser to view that file.

@kindex ( @r{(Dired)}
@findex dired-hide-details-mode
@vindex dired-hide-details-hide-symlink-targets
@vindex dired-hide-details-hide-information-lines
@cindex hiding details in Dired
  The command @kbd{(} (@code{dired-hide-details-mode}) toggles whether
details, such as ownership or file permissions, are visible in the
current Dired buffer.  By default, it also hides the targets of
symbolic links, and all lines other than the header line and
file/directory listings.  To change this, customize the options
@code{dired-hide-details-hide-symlink-targets} and
@code{dired-hide-details-hide-information-lines}, respectively.

@cindex Dired and version control
  If the directory you are visiting is under version control
(@pxref{Version Control}), then the normal VC diff and log commands
will operate on the selected files.

@findex dired-compare-directories
  The command @kbd{M-x dired-compare-directories} is used to compare
the current Dired buffer with another directory.  It marks all the files
that differ between the two directories.  It puts these marks
in all Dired buffers where these files are listed, which of course includes
the current buffer.

  The default comparison method (used if you type @key{RET} at the
prompt) is to compare just the file names---file names differ if
they do not appear in the other directory.  You can specify
more stringent comparisons by entering a Lisp expression, which can
refer to the variables @code{size1} and @code{size2}, the respective
file sizes; @code{mtime1} and @code{mtime2}, the last modification
times in seconds, as floating point numbers; and @code{fa1} and
@code{fa2}, the respective file attribute lists (as returned by the
function @code{file-attributes}).  This expression is evaluated for
each pair of like-named files, and files differ if the expression's
value is non-@code{nil}.

  For instance, the sequence @kbd{M-x dired-compare-directories
@key{RET} (> mtime1 mtime2) @key{RET}} marks files newer in this
directory than in the other, and marks files older in the other
directory than in this one.  It also marks files with no counterpart,
in both directories, as always.

@cindex drag and drop, Dired
@vindex dired-mouse-drag-files
  On the X Window System, Emacs supports the drag and drop protocol.
You can drag a file object from another program, and drop it onto a
Dired buffer; this either moves, copies, or creates a link to the file
in that directory.  Precisely which action is taken is determined by
the originating program.  Dragging files out of a Dired buffer is also
supported, by enabling the user option @code{dired-mouse-drag-files},
the mouse can be used to drag files onto other programs.  When set to
@code{link}, it will make the other program (typically a file manager)
create a symbolic link to the file; when set to @code{move}, it will
make the other program move the file to a new location, and setting it
to any other non-@code{nil} value will make the other program open or
create a copy of the file.  The keyboard modifiers pressed during the
drag-and-drop operation can also control what action the other program
takes towards the file.
