The Universal Argument Parser using Bash's builtin getops

the-universal-argument-parser-whith-long-options.sh

#!/bin/bash

# [MODIFICATION 1]
args=$@ # use builtin string substitution to simulate long options
args=${args//--long-option-a/-a} # replace `--long-option-a` with `-a`
args=${args//--long-option-b/-b} # replace `--long-option-b` with `-b`
args=${args//--long-option-c/-c} # replace `--long-option-c` with `-c`

# [MODIFICATION 2]
# replace unknown long options as 
# they can cause parsing issues.
shopt -s extglob
args=${args//--+([a-zA-Z0-9-])/-?} # replace `--unknown-long-option` with '-?'

## arrays
declare -A options;

# [MODIFICATION 3] 
# define the parameters
# using the silent mode
# set by the leading `:`
OPTSTRING=":a:b:c:d:e:f:"

# [MODIFICATION 4]
# use the modified `$args` instead of `$@`
while getopts "$OPTSTRING" name $args; do

      # if argument parameter was given
      if [[ ${OPTARG} ]]; then
        options[${name}]=${OPTARG};

      # if argument is just a flag
      else
        options[${name}]=${name};
      fi
done;

## shift the $@
shift $(( ${OPTIND} - 1 ));

# [MODIFICATION 5]
# print arguments
printf ' $@: %s\n' "$args"
printf ' -a: %s\n' ${options['a']};
printf ' -b: %s\n' ${options['b']};
printf ' -c: %s\n' ${options['c']};

the-universal-argument-parser.sh

# The Universal Argument Parser
# Source: https://www.vivaolinux.com.br/artigo/getopts-criando-scripts-Bash-com-parametros-e-argumentos-personalizaveis

## arrays
declare -A options;

## collect arguments
while getopts "$OPTSTRING" name; do

      # if argument parameter was given
      if [[ ${OPTARG} ]]; then
        options[${name}]=${OPTARG};

      # if argument is just a flag
      else
        options[${name}]=${name};
      fi

done;

## shift the $@
shift $(( ${OPTIND} - 1 ));

OUTPUT:

./the-universal-argument-parser-whith-long-options.sh --long-option-a 1 --long-option-b 2 --long-option-c 3 --unknown

 $@: -a 12 -b 2 -c 3 -?
 -a: 1
 -b: 2
 -c: 3