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Mon, 07 Dec 2009 13:02:34 +0100
Thunderbird 184.108.40.206 (X11/20081227)
Pascal J. Bourguignon wrote:
> Andreas Roehler <address@hidden> writes:
>> needed a check if a command exists on system.
>> Employed the following:
>> (defun system-command-exists-p (command)
>> "Return t if COMMAND is available on system. "
>> (let* ((cmd (format "type %s" command)))
>> (eq 0 (shell-command cmd))))
>> Any comments/suggestions?
> Use %S or (shell-quote-argument command).
> type is a built-in command specific to the sh familly of shells.
> Perhaps it would be a good idea to explicitely call up sh?
> It may be useful to return the path of the command:
> (defun system-command-exists-p (command)
> "Return t if COMMAND is available on system. "
> (let* ((cmd (format "/bin/sh -c 'type %s'"
> (shell-quote-argument command))))
> (when (eql 0 (shell-command cmd))
> (let ((result (shell-command-to-string cmd)))
> (if (string-match "^.* is \\(.*\\)\n$"result)
> (match-string 1 result)
> (mapcar (function system-command-exists-p)
> '("cat" "type" "foo"))
> --> ("/bin/cat" "a shell builtin" nil)
Thanks a lot.
Concerning the precise kind-of-"shell"-question, I'm not sure.
Case is to write a check for pack-unpack functions.
Presently dired-do-compress uses a hard-encoded "gzip", replaced here by
a choice so far.
Then testing all compressing/uncompressing possibilities, it turns out some
might not be installed.
type uncompress =>
uncompress is /usr/bin/uncompress
type compress =>
bash: type: compress: not found
Test should not fail, if these programms are not installed, rather give a
So far the issue here.
Think the shell-in-use should not matter, resp. will be selected already.
What about to write:
(cmd (format (concat (getenv "SHELL") " -c 'type %s'")