It's not news that the shell turns
.*
(dot asterisk)
into every name in the current directory that starts
with a dot:
.login
,
.profile
,
.bin
(I name my directory
that way), and so on - including
.
and
..
too.
Also, many people know that the shell turns
*/.*
into a list of the dot files in subdirectories:
foo/.exrc
,
foo/.hidden
,
bar/.xxx
-as well as
foo/.
,
foo/..
,
bar/.
, and
bar/..
, too.
(If that surprises you, look at the wildcard pattern closely - or try it
on your account with the
echo
command:
echo
*/.*
.)
What if you're trying to match just the subdirectory names, but not the
files in them?
The most direct way is:
*/.
-that matches
foo/.
,
bar/.
,
and so on.
The dot (
.
) entry in each directory
is a link to the directory itself (
18.2
,
14.4
)
,
so you can use it wherever you use the directory name.
For example, to get a list of the names of your subdirectories, type:
$
ls -d */.
bar/. foo/.
(The
-d
option (
16.8
)
tells
ls
to list the names of directories, not their contents.)
With some C shells (but not all), you don't need the trailing dot (
.
):
%
ls -d */
bar/ foo/
(The shell passes the slashes (
/
) to
ls
.
So, if you use the
ls
-F
option (
16.12
)
to put a slash after directory
names, the listing will show
two
slashes after each directory
name.)
When matching directory names that start with a dot,
the shells expand the
.*/
or
.*/.
and pass the result to
ls
-so you
really don't need the
ls
-a
option (
16.11
)
.
The
-a
is useful only when
you ask
ls
(not the shell) to read a directory and list the entries in it.
You don't have to use
ls
, of course.
The
echo
(
8.6
)
command will show the same list more simply.
Here's another example: a Bourne shell loop that runs a command in each
subdirectory of your home directory:
for dir in $HOME/*/.
do
cd $dir
...
Do something
...
done
That doesn't take care of subdirectories
whose names begin with a dot,
like my
.bin
-but article
15.5
shows a way to do that too.
Article
21.12
shows a related trick that doesn't involve the shell or wildcards:
making a pathname
that will match only a directory.