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I have a usecase wherein I need to support multiple character option. Currently I am using single character option for getopts. Multi-character option is desirable.What's the best way of doing this? I came across articles implementing a manual parser for this usecase,but is that optimal with respect to performance.

I want something like -ab to be treated as -ab only and not -a -b . Also is it a good coding practice?

This is just done to make the options more meaningful as opposed to single char options which do not provide complete information about that option.

Important: I also want optargs with these multi-character options .Example -ab "sdfd" .

Here's the code

while getopts ":s:p:q:j:o" opt; do case ${opt} in s) only_save=TRUE new_tok=$OPTARG ;; p) only_upload_enum_json=TRUE enum="job_status" new_tok=$OPTARG ;; q) only_upload_enum_json=TRUE enum="lifecycle_state" new_tok=$OPTARG ;; j) only_download_enum_json=TRUE enum=$OPTARG ;; o) only_download=TRUE ;; \?) echo " -s <token>" echo " -p <token>" echo " -q <token>" echo " -j <enum_name>" echo " -o <no value needed>" exit; ;; esac done

Here for job_status its desirable to use -js instead of -p to make it more meaningful.and similarly for lifecycle_state

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    but is that optimal with respect to performance. If you care about the performance of command line parsing, writing a shell script is a non-starter. Usually you don't really care how many micro- to milliseconds your program needs to parse a command line – so if this is an important metric in your program, you really need to explain what performance you're looking for. The fact that you'd only need command line parsing when you start a new process means that you're worrying about a really small computational load (parsing) with a really large one (forking a shell process)! Commented Jun 30, 2023 at 12:18
  • Also is it a good coding practice? do you mean a good command line convention? Because good coding practice refers to the way you implemented some algorithm in code, and you're not sharing any code with us. Commented Jun 30, 2023 at 12:20
  • @MarcusMüller I've added the code now. Commented Jun 30, 2023 at 12:27
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    No. getopts only supports single-character options. I use getopt in production code. Commented Jun 30, 2023 at 13:00
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    Then you need to pick a different tool that can support that usage. Bash can't do it. Commented Jun 30, 2023 at 13:14

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Personally, I'm using getopt, not getopts, in a function called option_handling, see my shell-script-template below.

If you want to pass args with your options you can:

Let's say your option is -z 'something'...

[...] --options hVvz: [...] -z)args="$2"; shift2;;

You want to hab a look at /usr/share/doc/util-linux/examples/getopt-parse.bash --that should come preinstalled.

Here's the template:

#!/usr/bin/env -S bash - #=============================================================================== # # FILE: <<filename here>> # # USAGE: # # DESCRIPTION: # # OPTIONS: --- # REQUIREMENTS: --- # BUGS: --- # NOTES: --- # AUTHOR: # ORGANIZATION: # CREATED: # LICENSE: BSD-3-CLAUSE # REVISION: --- #=============================================================================== #=== Init ====================================================================== set -o nounset # exit on unset variables. set -o errexit # exit on any error. set -o errtrace # any trap on ERR is inherited #set -o xtrace # show expanded command before execution. unalias -a # avoid rm being aliased to rm -rf and similar issues LANG=C # avoid locale issues VERBOSE= # Don't be verbose, unless given '-v'-option ScriptVersion="1.0" trap "cleanup" EXIT SIGTERM #=== Functions ================================================================= usage (){ echo " Usage : ${0##/*/} [options] [--] Options: -h|--help Display this message -V|--version Display script version -v|--verbose Print informational text " exit 0 } # ---------- end of function usage ---------- option_handling () { # see /usr/share/doc/util-linux/examples/getopt-parse.bash OPTS=$(getopt --name "$0" \ --options hVv \ --longoptions help,version,verbose \ --shell bash \ -- "$@") \ || (echo; echo "See above and try \"$0 --help\""; echo ; exit 1) eval set -- "$OPTS" unset OPTS while true ; do case "$1" in -h|--help) usage ;; -V|--version) echo "$0 -- Version $ScriptVersion"; exit 0 ;; -v|--verbose) VERBOSE=true shift ;; --) shift ; break ;; *) echo "I don't know what to do with \"$1\". Try $0 --help" exit 1 ;; esac done } # ---------- end of function option_handling ---------- cleanup () { # Will be called by the trap above, no need to call it manually. : } # ---------- end of function cleanup ---------- # see https://github.com/markgraf/flatten.sh about this . ~/scripting/library.bash/lazy.lib #=== Main ====================================================================== main () { option_handling "$@" } # ---------- end of function main ---------- main "$@" #=== End =======================================================================
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