Is mixing getopts with positional parameters possible?

I want to design a shell script as a wrapper for a couple of scripts. I would like to specify parameters for myshell.sh using getopts and pass the remaining parameters in the same order to the script specified.

If myshell.sh is executed like:

myshell.sh -h hostname -s test.sh -d waittime param1 param2 param3

myshell.sh param1 param2 -h hostname param3 -d waittime -s test.sh

myshell.sh param1 -h hostname -d waittime -s test.sh param2 param3

All of the above should be able to call as

test.sh param1 param2 param3

Is it possible to utilize the options parameters in the myshell.sh and post remaining parameters to underlying script?

Solution 1:

I wanted to do something similar to the OP, and I found the relevant information I required here and here

Essentially if you want to do something like:

script.sh [options] ARG1 ARG2

Then get your options like this:

while getopts "h:u:p:d:" flag; do
case "$flag" in
    h) HOSTNAME=$OPTARG;;
    u) USERNAME=$OPTARG;;
    p) PASSWORD=$OPTARG;;
    d) DATABASE=$OPTARG;;
esac
done

And then you can get your positional arguments like this:

ARG1=${@:$OPTIND:1}
ARG2=${@:$OPTIND+1:1}

More information and details are available through the link above.

Hope that helps!!

Solution 2:

Mix opts and args :

ARGS=""
echo "options :"
while [ $# -gt 0 ]
do
    unset OPTIND
    unset OPTARG
    while getopts as:c:  options
    do
    case $options in
            a)  echo "option a  no optarg"
                    ;;
            s)  serveur="$OPTARG"
                    echo "option s = $serveur"
                    ;;
            c)  cible="$OPTARG"
                    echo "option c = $cible"
                    ;;
        esac
   done
   shift $((OPTIND-1))
   ARGS="${ARGS} $1 "
   shift
done

echo "ARGS : $ARGS"
exit 1

Result:

bash test.sh  -a  arg1 arg2 -s serveur -c cible  arg3
options :
option a  no optarg
option s = serveur
option c = cible
ARGS :  arg1  arg2  arg3

Solution 3:

myshell.sh:

#!/bin/bash

script_args=()
while [ $OPTIND -le "$#" ]
do
    if getopts h:d:s: option
    then
        case $option
        in
            h) host_name="$OPTARG";;
            d) wait_time="$OPTARG";;
            s) script="$OPTARG";;
        esac
    else
        script_args+=("${!OPTIND}")
        ((OPTIND++))
    fi
done

"$script" "${script_args[@]}"

test.sh:

#!/bin/bash
echo "$0 $@"

Testing the OP's cases:

$ PATH+=:.  # Use the cases as written without prepending ./ to the scripts
$ myshell.sh -h hostname -s test.sh -d waittime param1 param2 param3
./test.sh param1 param2 param3
$ myshell.sh param1 param2 -h hostname param3 -d waittime -s test.sh
./test.sh param1 param2 param3
$ myshell.sh param1 -h hostname -d waittime -s test.sh param2 param3
./test.sh param1 param2 param3

What's going on:

getopts will fail if it encounters a positional parameter. If it's used as a loop condition, the loop would break prematurely whenever positional parameters appear before options, as they do in two of the test cases.

So instead, this loop breaks only once all parameters have been processed. If getopts doesn't recognize something, we just assume it's a positional parameter, and stuff it into an array while manually incrementing getopts's counter.

Possible improvements:

As written, the child script can't accept options (only positional parameters), since getopts in the wrapper script will eat those and print an error message, while treating any argument like a positional parameter:

$ myshell.sh param1 param2 -h hostname -d waittime -s test.sh -a opt1 param3
./myshell.sh: illegal option -- a
./test.sh param1 param2 opt1 param3

If we know the child script can only accept positional parameters, then myshell.sh should probably halt on an unrecognized option. That could be as simple as adding a default last case at the end of the case block:

            \?) exit 1;;

$ myshell.sh param1 param2 -h hostname -d waittime -s test.sh -a opt1 param3
./myshell.sh: illegal option -- a

If the child script needs to accept options (as long as they don't collide with the options in myshell.sh), we could switch getopts to silent error reporting by prepending a colon to the option string:

    if getopts :h:d:s: option

Then we'd use the default last case to stuff any unrecognized option into script_args:

            \?) script_args+=("-$OPTARG");;

$ myshell.sh param1 param2 -h hostname -d waittime -s test.sh -a opt1 param3
./test.sh param1 param2 -a opt1 param3