Marcus Noble

I'm not sure how I've never come across this before but while looking through the Scaleway Kosmos multi-cloud init script I dicovered the getopts utility.

getopts makes it easier to parse arguments passed to a shell script by defining which letters your script supports. It supports both boolean and string style arguments but only supports single letter flags. (e.g. -h and not --help)

Example usage:

#!/bin/bash

NAME="World"
FORCE=false

showHelp() {
    echo "Usage: example.sh [args]"
    exit 0
}

while getopts 'hfn:' FLAG
do
  case $FLAG in
    h) showHelp ;;
    f) FORCE=true ;;
    n) NAME=$OPTARG ;;
    *) echo "Unsupported argument flag passed" ;;
  esac
done

echo "Hello, $NAME"

Notice the : following the n? That indicates that a value should follow the argument flag (n in this example) and will be made available as the OPTARG variable.