#!/bin/bash

process_u() {

    if [ ! -z "${2##*[!0-9]*}" ]; then

        # Single shared static ID.

        echo "user($1) = $2"

        echo "group($1) = $2"

    elif [[ $2 == *:* ]]; then

        # UID:<group>.

        uid=$(echo $2 | cut -d':' -f1 -)

        group=$(echo $2 | cut -d':' -f2 -)

        if [ ! -z "${group##*[!0-9]*}" ]; then

            # UID:GID.

            echo "user($1) = ${uid}"

            echo "group($1) = ${group}"

        else

            # UID:<groupname>.

            echo "user($1) = ${uid}"

            echo "group(${group})"

        fi

    else

        # Dynamic (or something else uninteresting).

        echo "user($1)"

        echo "group($1)"

    fi

}

process_g() {

    if [ ! -z "${2##*[!0-9]*}" ]; then

        # Static GID.

        echo "group($1) = $2"

    else

        # Dynamic (or something else uninteresting).

        echo "group($1)"

    fi

}

parse() {

    while read line; do

        [ "${line:0:1}" = '#' -o "${line:0:1}" = ';' ] && continue

        line="${line## *}"

        [ -z "$line" ] && continue

        set -- $line

        case "$1" in

            ('u')

                process_u "$2" "$3"

                ;;

            ('g')

                process_g "$2" "$3"

                ;;

            ('m')

                echo "user($2)"

                echo "group($3)"

                ;;

        esac

    done

}

while read fn; do

    parse < "$fn"

done