BashNamedArgs

params.sh

#!/usr/bin/env bash

set -o pipefail
set -o nounset # fail on unset var usage
set -o errexit # exit on command failure

err_report() {
    echo "Exited with error on line $1"
}
# prints errors out along with line number
trap 'err_report $LINENO' ERR

# changes bash word splitting to newline and tabs
IFS=$'\n\t'

function print_help {
    echo "usage: $0 [options] <param>"
    echo "Short Description"
    echo ""
    echo "-h,--help print this help"
    echo "--param1 Description of param1"
    echo "--param2 Description of param2"
}
# Create an array to store positional args
POSITIONAL=()

# loop over args one at a time
# always sets key to $1 since we keep shifting the args list to the left (if its  key=value then shift left twice)
while [[ $# -gt 0 ]]; do
    key="$1"
    case $key in
        -h|--help)
            print_help
            exit 1
            ;;
        --param1)
            PARAM_1="$2"
            #shift twice. once for key, once for value
            shift
            shift
            ;;
        --param2)
            PARAM_2=$2
            shift
            shift
            ;;
        *)    # unknown option
            POSITIONAL+=("$1") # save it in an array for later
            shift # past argument
            ;;
    esac
done

set +u #enable unset var usage
set -- "${POSITIONAL[@]}" # restore positional parameters
NAME="$1" #since positionals are restored, we can get first one
set -u #disable again

echo "Hello $NAME"

echo "Hello ${PARAM_2}" # this will error out if --param2 is not set
echo "Hello ${PARAM_2:-}" # This will not result in an error since ${PARAM_2:-} tests if the var is set first