Script to add a service account on OSX.

osx_useradd.sh

#!/bin/sh
#
# This is free and unencumbered software released into the public domain.
#
# Created by Nils Kollandsrud and modified by Adi Roiban.
#
# Script for creating a new service account on OSX.
# It will create a dedicated group and username for the service account.

# usage: sh shellname.sh username
NEWUSERNAME=$1

# Check that we are superuser (i.e. $(id -u) is zero)
if (( $(id -u) )) ; then
    echo "This script needs to run as root"
    exit 1
fi

UserNameNotUnused=$(dscacheutil -q user | grep 'name: '$NEWUSERNAME)
if [ "$UserNameNotUnused" != "" ]; then
    echo "User $NEWUSERNAME already exists. Creation aborted!"
    exit 1
fi

# User does not exists, so we can go and create it.
NEXTUID=$(dscl . -list /Users UniqueID | awk 'BEGIN{i=0}{if($2>i)i=$2}END{print i+1}')
NEXTGID=$(dscl . -list /Groups PrimaryGroupID | awk 'BEGIN{i=0}{if($2>i)i=$2}END{print i+1}')

printf "Ready to create user/group $NEWUSERNAME with uid: $NEXTUID and gid: $NEXTGID\nEnter YES to continue\n"

read CONFIRMATION

if [ "$CONFIRMATION" != "YES" ] ; then
    echo "Aborted as confirmation was not given!"
    exit 1
fi

dscl . create /Groups/$NEWUSERNAME
dscl . create /Groups/$NEWUSERNAME PrimaryGroupID $NEXTGID
dscl . create /Groups/$NEWUSERNAME Password '*'
dscl . create /Users/$NEWUSERNAME
dscl . create /Users/$NEWUSERNAME UniqueID $NEXTUID
dscl . create /Users/$NEWUSERNAME PrimaryGroupID $NEXTGID
dscl . create /Users/$NEWUSERNAME UserShell /usr/bin/false
dscl . create /Users/$NEWUSERNAME NFSHomeDirectory /var/empty
dscl . create /Users/$NEWUSERNAME Password '*'
dscl . delete /Users/$NEWUSERNAME PasswordPolicyOptions
dscl . delete /Users/$NEWUSERNAME AuthenticationAuthority

echo "$NEWUSERNAME service account has been created."
echo "User ID: $NEXTUID"
echo "Group ID: $NEXTGID"