Ways to provide list of parameters to options in shell scripts?

Question

Basically I am making a script where I would like to give a list of parameters to some option, say -l, eg:

usr@domain:$./somescript -l hi bye cry nigh

The list specified to -l would be then stored into a specific array and iterated over.

So far, I have been using these lines from Arch linux's mkinitcpio script to do so. This allows one to specify a comma-separated list to an option:

_optaddhooks()

while :; do
    case $1 in
        -A|--add|--addhooks)
            shift
            IFS=, read -r -a add <<< "$1"
            _optaddhooks+=("${add[@]}")
            unset add
            ;;

What are some other methods to do this, particularly when other options/parameters will be used? Can the list provided to an option be space separated? Or is specifying a list by "," (or some other character") easier to manage?

markp-fuso · Accepted Answer · 2020-12-15T02:50:44.940

UPDATE: OP is looking for a non-getopts solution; adding a -l option to the current code:

NOTE: OP has shown the command line flag as -l so not sure what the -A|-add|--addhooks) relates to ... ???

unset _optaddhooks

while :; do
    case "${1}" in
        -A|--add|--addhooks)
            shift
            ....
            ;;

        -a) shift
            vara="${1}"
            ;;
        -l) shift
            _optaddhooks=( ${1} )
            ;;
        -z) shift
            varz="${1}"
            ;;
        ....
    esac
done

OP would still use the same command line as in the earlier answer (below):

$ ./somescript -a this_is_a -l 'hi bye cry nigh' -z 123456

If you're willing to wrap the -l args in quotes you could then pass the args as a single parameter and then have bash parse this parameter however you wish.

One idea to load the -l args into an array named _optaddhooks[]:

$ cat somescript
#!/usr/bin/bash

while getopts :a:l:z: opt
do
    case ${opt} in
        a)   vara="${OPTARG}"           ;;
        l)   _optaddhooks=( ${OPTARG} ) ;;
        z)   varz="${OPTARG}"           ;;
        *)   echo "Sorry, don't understand the option '${opt}'" ;;
    esac
done

typeset -p vara _optaddhooks varz

A sample run:

$ ./somescript -a this_is_a -l 'hi bye cry nigh' -z 123456
declare -- vara="this_is_a"
declare -a _optaddhooks=([0]="hi" [1]="bye" [2]="cry" [3]="nigh")
declare -- varz="123456"

While this was a simple example, it should be easy enough to modify the code (l section of the case statement) as needed.

Only recently dived into the topic of options/parameters in bash. Most tutorials teach without getopts. A couple scripts I viewed on my computer (mkinitcpio & healthd) did not use getopts, so I figured why not try without getopts. — Zage12, Dec 15 '20 at 01:57
@Zage12 ok, I've updated the answer to fit into your current code, though I'm confused as to whether the command line flag is `-l` or `-A/--add/--addhoks`; for sake of the answer I've opted to use `-l` throughout — markp-fuso, Dec 15 '20 at 02:51
The ```-A/--add/--addhooks``` was from a system file. So yes, -l should be the option. — Zage12, Dec 15 '20 at 05:10

Ways to provide list of parameters to options in shell scripts?

1 Answers1