How to output piped stdout in bash script from getopts?

Question

I have the following snippet:

#!/bin/bash

OPTIND=1
while getopts ":m:t" params; do
    case "${params}" in

        m)
             bar=$OPTARG ;;
        t)
            foo=$OPTARG ;;

        \?) 
            "Invalid option: -$OPTARG" >&2
            print_usage 
            exit 2
            ;;

        :)
            echo "Option -$OPTARG requires an argument." >&2
            print_usage
            exit 2
            ;;

        esac

done
shift "$(( OPTIND-1 ))"
echo "${foo}"  && echo  "${bar}"

How can I output the stdout using pipes through this script?

For example:

echo "this is the test" | bash getoptscript.sh -m - 

And it should provide : this is the test as the output.

Answer 1

Rather than taking the string as a command line argument, you may simply use cat to read the script's standard input:

printf '%s\n' "$foo"
if [ "$bar" = "-" ]; then
    # assume data is on standard input
    cat
else
    print '%s\n' "$bar"
fi

Answer 2

By piping the output to xargs, which converts its input into arguments:

echo "this is the test" | xargs bash getoptscript.sh -m - 

Which will result in:

bash getoptscript.sh -m - this is the test