adduser

#!/bin/bash -e

if [[ -x /usr/sbin/adduser ]]; then
  exec /usr/sbin/adduser "$@"
fi

NEW_USERNAME="$1"
if [ -z "$NEW_USERNAME" ]
then
  echo "Usage: $(basename "$0") [username]" >&2
  exit 1
fi
if id "$NEW_USERNAME" 2> /dev/null
then
  echo "$(basename "$0"): User \"$NEW_USERNAME\" already exists." >&2
  exit 1
fi

NEW_UID=$(( $(dscl . -list /Users UniqueID | awk '{print $2}' | sort -n | tail -1) + 1 ))

if ! [ $NEW_UID -gt 500 ]
then
  echo "$(basename "$0"): Could not determine new UID." >&2
  exit 1
fi

dscl . create "/Users/$NEW_USERNAME"
dscl . create "/Users/$NEW_USERNAME" UniqueID $NEW_UID
dscl . create "/Users/$NEW_USERNAME" PrimaryGroupID 20
dscl . delete "/Users/$NEW_USERNAME" AuthenticationAuthority
dscl . create "/Users/$NEW_USERNAME" Password '*'
dscl . create "/Users/$NEW_USERNAME" UserShell /bin/bash
dscl . create "/Users/$NEW_USERNAME" NFSHomeDirectory "/Users/$NEW_USERNAME"
cd /tmp
createhomedir -c -u "$NEW_USERNAME"