Alternatively and you might have to do some porting to follow this path, you could locate and install a command-line XMPP/Jabber client, and use that. Here's a list of some of the available clients.
osascript. For example:
osascript -e 'tell app "Finder" to display dialog "Hello World"'
Replacing “Finder” with whatever app you desire. Note if that app is backgrounded, the dialog will appear in the background too. To always show in the foreground, use “System Events” as the app:
osascript -e 'tell app "System Events" to display dialog "Hello World"'
Read more on Mac OS X Hints.
osascript is a tool to execute AppleScript within a shell/script.
Here is Apple's introductory guide:https://developer.apple.com/library/mac/documentation/AppleScript/Conceptual/AppleScriptLangGuide/introduction/ASLR_intro.html
Additionally, you can open Script Editor.app (in /Applications/Utilities if your on OS X 10.11). From the menu bar select Window > Library to browse library documentation.