Playing with Zenity

#!/bin/sh

TITLE="FunzAlot"
LOGGEDIN=0

systemCheck() {
  UNAME=`which uname`
  GREP=`which egrep`
  GREP_OPTIONS=""
  CUT=`which cut`
  READLINK=`which readlink`
  XARGS=`which xargs`
  DIRNAME=`which dirname`
  MKTEMP=`which mktemp`
  RM=`which rm`
  CAT=`which cat`
  SED=`which sed`

  if [ -z "$UNAME" -o -z "$GREP" -o -z "$CUT" -o -z "$MKTEMP" -o -z "$RM" -o -z "$CAT" -o -z "$SED" ]; then
    message "Required tools are missing - check beginning of \"$0\" file for details."
    exit 1
  fi
}

message() {
  if [ -n "`which zenity`" ]; then
    zenity --error --title="$TITLE" --text="$1"
  elif [ -n "`which kdialog`" ]; then
    kdialog --error "$1" --title "$TITLE"
  elif [ -n "`which xmessage`" ]; then
    xmessage -center "ERROR: $TITLE: $1"
  elif [ -n "`which notify-send`" ]; then
    notify-send "ERROR: $TITLE: $1"
  else
    printf "ERROR: $TITLE\n$1\n"
  fi
}

login() {
  ENTRY=`zenity --password --username`

  case $? in
    0)
      UN="`echo $ENTRY | cut -d'|' -f1`"
      PW="`echo $ENTRY | cut -d'|' -f2`"
      if [ $UN == "jessica" ] && [ $PW == "Testing123" ]; then
        LOGGEDIN=1
        return
      else
        LOGGEDIN=0
        zenity --notification --window-icon="warning" --text="The username and password are incorrect"
      fi
      ;;
    1)
      message "Stop login."
      exit 0
      ;;
   -1)
      message "An unexpected error has occurred."
      exit 1
      ;;
  esac
}

main() {
  while [ $LOGGEDIN -ne 1 ]; do
    login
  done
}


main