Globstar: New Bash Globbing Option
In shell-speak, globbing is what the shell does when you use a wildcard in a command (e.g. * or ?). Globbing is matching the wildcard pattern and returning the file and directory names that match and then replacing the wildcard pattern in the command with the matched items. Bash version 4.0 adds a new globbing option called globstar which treats the pattern ** differently when it's set.
Normally, if you use the pattern ** on the command line it acts the same as the * pattern. For example, given the following directory:
$ ls -l total 8 -rw-r--r-- 1 mitch users 0 2010-05-05 10:36 a -rw-r--r-- 1 mitch users 0 2010-05-05 10:36 b drwxr-xr-x 2 mitch users 4096 2010-05-05 10:36 c drwxr-xr-x 2 mitch users 4096 2010-05-05 10:36 d
if you execute the following commands:
$ for i in ** > do > echo $i > done
you get the following output:
a b c d
If you now set the globstar option with the following command:
$ shopt -s globstar
and then re-run the for loop from above, you now get:
a b c c/e d d/f
With globstar set, bash recurses all the directories. Note that this will recurse all directory levels, not just one level.
You can see if globstar is set by issuing the shopt command without any arguments:
$ shopt ... force_fignore on globstar on gnu_errfmt off ...
or if you want to test it in a script you can use the -q option to shopt and test the exit status, for example:
if shopt -q globstar; then ... if
Mitch Frazier is an Associate Editor for Linux Journal.
- Readers' Choice Awards 2013
- Mars Needs Women
- RSS Feeds
- Sublime Text: One Editor to Rule Them All?
- December 2013 Issue of Linux Journal: Readers' Choice
- Raspberry Pi: the Perfect Home Server
- Linux Systems Administrator
- IBM Will Minimize Impact of Future Disasters
- Senior Perl Developer
- Technical Support Rep
- why is GNOME 3 in the fifth position at 14.1 %?
5 hours 27 min ago
- Sublime Is Brilliant!
10 hours 30 min ago
10 hours 50 min ago
- Rapid[Disk,Cache] better than native ram caching?
11 hours 15 min ago
- Nothing is perfect
11 hours 28 min ago
- Mixtapes Community
17 hours 7 min ago
- KDE is one true DE
17 hours 41 min ago
- Command Line Shells (Bash, Zsh, etc.) are 2nd place
18 hours 10 min ago
20 hours 5 min ago
- yes it's Jupiter Broadcasting
21 hours 24 min ago