Shell test conditions and exit codes
Tutorials – Shell Scripting
The Bash shell uses different criteria to make decisions. Learn how to teach your shell scripts to make the right choice.
In the previous installment of this series [1], I described how to add different possible courses of action to a script, so that the script can choose by itself which action to execute while running. In this issue, I will explain how to teach a script to choose which of the available actions to execute.
Often, the real decision-making challenge lies not in figuring out whether your shell script needs a while
loop or some nested if
statements but rather in determining the conditions that will tell your script when it should stop that loop or which branch of that "if" statement to execute. The main Bash tools for this purpose are a big set of test operators (see the descriptions online [2] [3] [4]) and their corresponding syntax, which can evaluate whether some condition is true or false. By contrast, exit status codes [5] are the traces that built-in commands, or whole scripts, leave behind to communicate their achievements.
In this article you will learn through examples and working code:
[...]
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you’ve found an article to be beneficial.

News
-
openSUSE Joins End of 10
openSUSE has decided to not only join the End of 10 movement but it also will no longer support the Deepin Desktop Environment.
-
New Version of Flatpak Released
Flatpak 1.16.1 is now available as the latest, stable version with various improvements.
-
IBM Announces Powerhouse Linux Server
IBM has unleashed a seriously powerful Linux server with the LinuxONE Emperor 5.
-
Plasma Ends LTS Releases
The KDE Plasma development team is doing away with the LTS releases for a good reason.
-
Arch Linux Available for Windows Subsystem for Linux
If you've ever wanted to use a rolling release distribution with WSL, now's your chance.
-
System76 Releases COSMIC Alpha 7
With scores of bug fixes and a really cool workspaces feature, COSMIC is looking to soon migrate from alpha to beta.
-
OpenMandriva Lx 6.0 Available for Installation
The latest release of OpenMandriva has arrived with a new kernel, an updated Plasma desktop, and a server edition.
-
TrueNAS 25.04 Arrives with Thousands of Changes
One of the most popular Linux-based NAS solutions has rolled out the latest edition, based on Ubuntu 25.04.
-
Fedora 42 Available with Two New Spins
The latest release from the Fedora Project includes the usual updates, a new kernel, an official KDE Plasma spin, and a new System76 spin.
-
So Long, ArcoLinux
The ArcoLinux distribution is the latest Linux distribution to shut down.