Improve the dired-guess-shell-alist-user doc string

* lisp/dired-x.el (dired-guess-shell-alist-user): Document how
REGEXP is used (bug#17251).

1 files changed, 6 insertions, 1 deletions

diff --git a/lisp/dired-x.el b/lisp/dired-x.el
index 56f7f4724ac..6619a391673 100644
--- a/lisp/dired-x.el
+++ b/lisp/dired-x.el
@@ -941,10 +941,15 @@ Each element of this list looks like
 
     (REGEXP COMMAND...)
 
-where each COMMAND can either be a string or a Lisp expression that evaluates
+COMMAND will be used if REGEXP matches the file to be processed.
+If several files are to be processed, REGEXP has to match all the
+files.
+
+Each COMMAND can either be a string or a Lisp expression that evaluates
 to a string.  If this expression needs to consult the name of the file for
 which the shell commands are being requested, it can access that file name
 as the variable `file'.
+
 If several COMMANDs are given, the first one will be the default
 and the rest will be added temporarily to the history and can be retrieved
 with \\[previous-history-element] (M-p) .