What's the Linux equivalent of OS X's Growl?

I want to write scripts on Ubuntu that will notify the user through a tool analogous to Growl on OS X (specifically, the growlnotify command-line tool). What's the equivalent tool on Linux called?

Ubuntu can show notifications, which seem to be equivalent to Growl. It is accessible through DBus (for programs) and through the notify-send command (for shell scripts).

There is a Growl port for Linux. Found here: Growl-for-linux

if you are using KDE, it is real easy! just use the kdialog command that is built-in to KDE, as in the example below:

kdialog --passivepopup "Example text"

if you happen to be using plain ubuntu, then you need to install the libnotify-bin package by issuing the following command:

sudo apt-get install libnotify-bin

and then you can send messages with like this:

notify-send "Example text"

the kdialog is a bit more interesting because it does way more than just send notifications from the command-line. you can actually build an interactive gui for your bash programs with it!

anyway, i hope this helps.