bash shell shorthand conditionals

This is a neat way in bash scripts to use conditionals. The basic syntax is:

[ condition ] && action
[ condition ] || action

counting files in a directory

[ $(ls -1 | wc -l) -ne 1 ] && echo “More than one file in this directory”

checking the number of args passed

[ $# -eq 1 ] || echo "Expecting one argument"

you can also group multiple actions together as follows:

[ $# -eq 1 ] || { echo "Expecting one argument"; exit 1; }