https://github.com/agriffis/pure-getopt

drop-in replacement for GNU getopt implemented in pure Bash
https://github.com/agriffis/pure-getopt

bash getopt

Last synced: 5 days ago
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drop-in replacement for GNU getopt implemented in pure Bash

• Host: GitHub
• URL: https://github.com/agriffis/pure-getopt
• Owner: agriffis
• License: mit
• Created: 2013-03-19T19:27:09.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2021-02-01T17:05:21.000Z (almost 4 years ago)
• Last Synced: 2024-08-04T04:09:18.906Z (3 months ago)
• Topics: bash, getopt
• Language: Shell
• Size: 83 KB
• Stars: 56
• Watchers: 4
• Forks: 7
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# pure-getopt

[![Build Status](https://travis-ci.com/agriffis/pure-getopt.svg?branch=master)](https://travis-ci.com/github/agriffis/pure-getopt)

pure-getopt is a drop-in replacement for GNU getopt, implemented in pure

Bash compatible back to 2.05b. It makes no external calls and faithfully

reimplements GNU getopt features, including:

 * all three calling forms in the synopsis

 * all getopt options

 * matching error messages

 * matching return codes

 * proper handling of abbreviated long options

 * alternative parsing mode (long options with single dash)

 * GETOPT_COMPATIBLE flag

 * POSIXLY_CORRECT flag

 * leading + or - on options string

# How to use it

pure-getopt provides a single bash function `getopt` that you can insert

directly into your script. It should be defined before calling `getopt` from

your code, so either place the definition above your code, or use this

pattern (recommended):

```bash

#!/bin/bash

main() {

    declare argv

    argv=$(getopt -o fb: --long foo,bar: -- "$@") || return

    eval "set -- $argv"

    declare foo=false bar=

    while true; do

        case $1 in

            f|foo) foo=true ; shift ;;

            b|bar) bar=$2 ; shift 2 ;;

            --) break ;;

        esac

    done

    # etc

}

# INSERT getopt function here

getopt() {

    ...

}

# CALL main at very bottom, passing script args.

# The test here distinguishes script execution from "source myscript.bash" which

# will define the functions without calling main, for calling functions from

# another script or testing at the command-line.

[[ $BASH_SOURCE != "$0" ]] || main "$@"

```

# Differences between pure-getopt and GNU getopt

The only intentional divergences between pure-getopt and GNU getopt are

either inconsequential or due to bugs in GNU getopt:

 1. GNU getopt mishandles ambiguities in abbreviated long options, for

    example this doesn't produce an error message:

        getopt -o '' --long xy,xz -- --x

    but this does produce an error message:

        getopt -o '' --long xy,xz: -- --x

    Pure-getopt generates an error message in both cases, diverging from

    GNU getopt to fix this bug.

 2. In the case of an ambiguous long option with an argument, GNU getopt

    generates an error message that includes the argument:

        getopt: option '--x=foo' is ambiguous; possibilities: '--xy' '--xz'

    We consider this a bug in GNU getopt, since the value might be very

    long and inappropriate for printing to the screen, and since GNU getopt

    ordinarily omits the value in its error messages. Pure-getopt's error

    message in this case is:

        getopt: option '--x' is ambiguous; possibilities: '--xy' '--xz'

 3. Pure-getopt uses a different method of quoting the output. The result

    is the same as GNU getopt when eval'd by the shell.

# References

 * [getopt in util-linux](http://software.frodo.looijaard.name/getopt/)