Bash expansions

admin — Sat, 30 Nov 2013 17:18:35 +0000

In this post you will learn about bash expansions, you probably already used them if you have done something like “ls *.txt”, basically the shell does some processing on the command line before actually executing it, which enables us to do a numbers of things, like using variables.

Here is a small cheatsheet of the most useful expansions:

Brace expansion
List: {1,2,3}

Range: {20..30}

Filename expansion (also know as globbing)
*.sh -> expands to all file names that have an extension of .sh [st]* -> expands to all file names that start with either an 's' or a 't'

Tip: if you want to use a especial character without it being expanded you can enclose it in quotes, for example: echo “test*”

Variable expansion
$SHELL -> /usr/bin/zsh

You can learn more here: http://www.gnu.org/software/bash/manual/html_node/Shell-Expansions.html

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Bash expansions