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.
Fast/Flexible Linux OS Recovery
On Demand Now
In this live one-hour webinar, learn how to enhance your existing backup strategies for complete disaster recovery preparedness using Storix System Backup Administrator (SBAdmin), a highly flexible full-system recovery solution for UNIX and Linux systems.
Join Linux Journal's Shawn Powers and David Huffman, President/CEO, Storix, Inc.
Free to Linux Journal readers.Register Now!
|Working with Command Arguments||May 28, 2016|
|Secure Desktops with Qubes: Installation||May 28, 2016|
|CentOS 6.8 Released||May 27, 2016|
|Secure Desktops with Qubes: Introduction||May 27, 2016|
|Chris Birchall's Re-Engineering Legacy Software (Manning Publications)||May 26, 2016|
|ServersCheck's Thermal Imaging Camera Sensor||May 25, 2016|
- Tips for Optimizing Linux Memory Usage
- Working with Command Arguments
- Secure Desktops with Qubes: Introduction
- Secure Desktops with Qubes: Installation
- Download "Linux Management with Red Hat Satellite: Measuring Business Impact and ROI"
- CentOS 6.8 Released
- The Italian Army Switches to LibreOffice
- Linux Mint 18
- Oracle vs. Google: Round 2
- The FBI and the Mozilla Foundation Lock Horns over Known Security Hole
Until recently, IBM’s Power Platform was looked upon as being the system that hosted IBM’s flavor of UNIX and proprietary operating system called IBM i. These servers often are found in medium-size businesses running ERP, CRM and financials for on-premise customers. By enabling the Power platform to run the Linux OS, IBM now has positioned Power to be the platform of choice for those already running Linux that are facing scalability issues, especially customers looking at analytics, big data or cloud computing.
￼Running Linux on IBM’s Power hardware offers some obvious benefits, including improved processing speed and memory bandwidth, inherent security, and simpler deployment and management. But if you look beyond the impressive architecture, you’ll also find an open ecosystem that has given rise to a strong, innovative community, as well as an inventory of system and network management applications that really help leverage the benefits offered by running Linux on Power.Get the Guide