key value parser for shell script for bash shell

argparse.sh

#!/bin/bash

## Copyright (c) 2020 mangalbhaskar. All Rights Reserved.
##__author__ = 'mangalbhaskar'
##----------------------------------------------------------
## key value parser for shell script for bash shell

## Reference and Credits:
## http://tldp.org/LDP/abs/html/parameter-substitution.html
## https://stackoverflow.com/questions/14370133/is-there-a-way-to-create-key-value-pairs-in-bash-script#14371026
## https://stackoverflow.com/questions/5499472/specify-command-line-arguments-like-name-value-pairs-for-shell-script

## @Example:
## ./argparse.sh --x="blah"
## ./argparse.sh --x="blah" --yy="qwert bye"
## ./argparse.sh x="blah" yy="qwert bye"
##----------------------------------------------------------

set -u

: ${1?
  'Usage:
  $0 --<key1>="<val1a> <val1b>" [ --<key2>="<val2a> <val2b>" | --<key3>="<val3>" ]'
}

declare -A args
while [[ "$#" > "0" ]]; do
  case "$1" in 
    (*=*)
        _key="${1%%=*}" &&  _key="${_key/--/}" && _val="${1#*=}"
        args[${_key}]="${_val}"
        (>&2 echo -e "key:val => ${_key}:${_val}")
        ;;
  esac
  shift
done
(>&2 echo -e "Total args: ${#args[@]}; Options: ${args[@]}")

## This additional can check for specific key
[[ -n "${args['path']+1}" ]] && (>&2 echo -e "key: 'path' exists") || (>&2 echo -e "key: 'path' does NOT exists");

In order to use the argparse as a modular script in utility function, save the following as argparse.sh:

declare -A args
while [[ "$#" > "0" ]]; do
  case "$1" in 
    (*=*)
        _key="${1%%=*}" &&  _key="${_key/--/}" && _val="${1#*=}"
        args[${_key}]="${_val}"
        # (>&2 echo -e "key:val => ${_key}:${_val}")
        ;;
  esac
  shift
done

And now it can be included in other functions in different scripts. Let's say there's another script called as test-argparse.sh; assuming both argparse.sh and test-argparse.sh are saved in the same directory,

function test-1-case-1-argparse() {
  local LSCRIPTS=$( cd "$( dirname "${BASH_SOURCE[0]}")" && pwd )

  source ${LSCRIPTS}/argparse.sh "$@"
  echo "Total: $# should be equal to ${#args[@]} and args: ${args[@]}"

  local key
  for key in "${!args[@]}"; do
    [[ -n "${args[${key}]+1}" ]] && echo "${key} = ${args[${key}]}" || echo "Key does not exists: ${key}"
  done
}

test-1-case-1-argparse  --user='blah' --group='dummy' --uid=1111 --gid=0000

Now execute test-argparse.sh:

bash test-argparse.sh

Output will be:

Total: 4 should be equal to 4 and args: 0000 blah 1111 dummy
gid = 0000
user = blah
uid = 1111
group = dummy

https://stackoverflow.com/a/63331082/748469