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 foo.tar and you press !, Dired will guess you want to ‘tar xvf’ it and suggest that as the default shell command.
The default is mentioned in brackets and you can type M-n to get the default into the minibuffer and then edit it, e.g., to change ‘tar xvf’ to ‘tar tvf’. If there are several commands for a given file, e.g., ‘xtex’ and ‘dvips’ for a .dvi file, you can type M-n several times to see each of the matching commands.
Dired only tries to guess a command for a single file, never for a list of marked files.
Predefined rules for shell commands. Set this to
nil to turn guessing off.
The elements of
dired-guess-shell-alist-user (defined by the
user) will override these rules.
nil, a user-defined alist of file regexps and their suggested
commands. These rules take precedence over the predefined rules in the
dired-guess-shell-alist-default (to which they are prepended)
dired-do-shell-command is run).
Each element of the alist looks like
where each 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.
If ‘*’ in the shell command, that means to substitute the file name.
You can set this variable in your ~/.emacs. For example, to add rules for ‘.foo’ and ‘.bar’ file extensions, write
(setq dired-guess-shell-alist-user (list (list "\\.foo$" "foo-command");; fixed rule ;; possibly more rules... (list "\\.bar$";; rule with condition test '(if condition "bar-command-1" "bar-command-2"))))
This will override any predefined rules for the same extensions.
dired-guess-shell-alist-user are matched case-insensitively.
nil, this is the name of the GNU Tar executable (e.g.,
‘tar’ or ‘gnutar’). GNU Tar’s ‘z’ switch is used for
compressed tar files.
If you don’t have GNU tar, set this to
nil: a pipe using ‘zcat’ is
nil value means that ‘-q’ is passed to
overriding a verbose option in the
GZIP environment variable.
A string of switches passed to
znew. An example is
‘-K’ which will make
znew keep a .Z file when it is
smaller than the .gz file.
History list for commands that read dired-shell commands.