Bash Shell

Bash Shell

Bash is the default shell on many operating systems in this era, including Apple OSX / MacOS, most Linux distributions, and on Windows when using Cygwin or the Microsoft-supplied Linux for Windows subsystem (itself based on the Ubuntu distribution of Linux).

Bash script options

There’s a few options you should always set when creating Bash shell scripts for safety reasons.

See also http://www.tldp.org/LDP/abs/html/options.html

Commonly, ‘set -eux’ is used.

#!/bin/bash
set -eux

# script goes here

This will set the script to fail on any error (e), fail on unset variables (u), and to expand commands and display them (x).

You want it to fail fast, before it does something unexpected because an earlier command failed.

You want it to fail on unset variables, to help catch typos and other errors.

It’s also a good idea to make it expand and echo the commands too, so if you have got something wrong you get a chance to hit break and halt execution.