#!/bin/sh
# osx-groupmod --- add, remove, or tweak groups on OSX
# Author: Noah Friedman <friedman@splode.com>
# Created: 2011-08-04
# Public domain

# $Id: osx-groupmod,v 1.2 2017/12/31 05:46:16 friedman Exp $

# Commentary:
# Code:

nextgid()
{
    max=`dscl . -list /Groups PrimaryGroupID | sort -ug -k2,2 | sed -ne '${s/^.* //p;}'`
    echo $(($max + 1))
}

groupadd()
{
    group=$1
      gid=${2:-`nextgid`}

    dscl . create /Groups/$group
    dscl . create /Groups/$group Password '*'
    dscl . create /Groups/$group PrimaryGroupID $gid
}

groupdel()
{
    dscl . delete /Groups/$1
}

groupadduser()
{
    group=$1
    shift

    for user in "$@"; do
        dscl . append /Groups/$group GroupMembership $user
    done
}

groupdeluser()
{
    group=$1
    shift

    for user in "$@"; do
        dscl . delete /Groups/$group GroupMembership $user
    done
}

######
##
######

usage()
{
    progname=${0##*/}

    exec 1>&2
    case $# in
        0 ) : ;;
        * ) echo $progname: "$@"; echo ;;
    esac

    echo "\
Usage: $progname add [groupname] {gid}
       $progname del [groupname]
       $progname adduser [groupname] [user] {more users...}
       $progname deluser [groupname] [user] {more users...}
"
    exit 1
}

main()
{
    case $1 in
        add | del | adduser | deluser ) cmd=$1; shift; group$cmd "$@" ;;
        * ) usage ;;
    esac
}

main "$@"

# eof