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I have created a script which takes parameters and arguments. I want to insert the --help argument.

I already know how to parse normal arguments with -, but I don't know how to parse the -- ones.

To parse options for test.sh -h, I use the following check:

while getopts ":h" opt; 
do 
case $opt in
    h ) {
            echo "help!!!"
            exit 1
    } ;;
esac
done

But I want to have the option to call the script with test.sh --help.

P.S. I am using Ubuntu 12.04… but it doesn't really matter.

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2 Answers 2

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getopts cannot handle long arguments:

$ ( set -- --help ; while getopts -- -help opt; do echo "$opt"; done )
-
h
e
l
p

If you want to handle long arguments, you need to write your own parser.

The GNU version of getopt does support parsing long options, but you'd be better off not using it; it's not portable, and non-GNU versions have a tendency to break on certain types of arguments. For example, they often cannot properly parse arguments with whitespace in them.

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  • Thanks. I have in the mean time found a solution in one of the shell scripts from /usr/bin :) I've edited the answer in my question Commented Feb 17, 2013 at 2:14
  • @bioShark Like I said, if you want to handle long arguments you need to write your own parser -- the script in your question is an example of that. :-) Commented Feb 17, 2013 at 2:18
  • There's no GNU version of getopt. There's a getopt in util-linux though which is likely the one you're referring to. Commented Sep 10, 2022 at 21:09
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The author of the question provided this solution:

I found the solution in one of the .sh scripts from /usr/bin

  if test "$#" -eq 1; then
    case "$1" in
      --help | --hel | --he | --h )
        func_usage; exit 0 ;;
      --version | --versio | --versi | --vers | --ver | --ve | --v )
        func_version; exit 0 ;;
    esac
  fi

Chris Down's comments on it:

Like I said, if you want to handle long arguments you need to write your own parser -- the script [that you found] is an example of that.

For the record the script you found is badly written. For example, the --version partial match could be rewritten just as --v*)(assuming you're okay with --vfoo).

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