Different ways for declaring a function's arguments in Bash scripts

001_position_args.sh

#!/bin/bash -xe

function byPosition () {
  echo "Variable in position 1: $1"
  echo "Variable in position 2: $2"
}

byPosition hola mundo

002_optional_args.sh

#!/bin/bash -xe

function optionalArgs () {
  var_1=${1:-foo}
  var_2=${2:-bar}

  echo "Variable 1: $var_1"
  echo "Variable 2: $var_2"
}

optionalArgs uno dos

003_named_args.sh

#!/bin/bash -xe

function namedWithGetOps () {
  while getopts ":p:s:" opt; do
    case $opt in
      p) first="$OPTARG";;
      s) second="$OPTARG";;
      \?) echo "Invalid option -$OPTARG" >&2;;
    esac
  done

  printf "Argument first is %s\n" "$first"
  printf "Argument second is %s\n" "$second"
}

namedWithGetOps -s segundo -p primero

Resources:

• Positional arguments
• Optional arguments
• Named arguments : getopts