Mini Shell

#!/usr/bin/bash

parse() {
    while read line; do
        [ "${line:0:1}" = '#' -o "${line:0:1}" = ';' ] && continue
        line="${line## *}"
        [ -z "$line" ] && continue
        set -- $line
        case "$1" in
            ('u')
                echo "user($2)"
                echo "group($2)"
                # TODO: user:group support
                ;;
            ('g')
                echo "group($2)"
                ;;
            ('m')
                echo "user($2)"
                echo "group($3)"
                ;;
        esac
    done
}

while read fn; do
    parse < "$fn"
done