Wildcards that Match Only Directories

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 (, ), 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 () 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 () 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 (). 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 () 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 shows a related trick that doesn't involve the shell or wildcards: making a pathname that will match only a directory.

- JP