GeekTool full review
There are three kinds of data GeekTool deals in, the first of which are log files. As your Mac goes about its business it records data in various logs – the system kernel, web server and console all generate their own – and these are displayed live. Other data that can be displayed include the results of any shell command or program and an updating shared directory listing. Netstat can be used to display active network connections, and you can pipe a live listing of your disk space usage with df.
GeekTool can also be used to display images on the desktop from network sources, a feature you could use to add an updating webcam shot to your desktop, or to cycle through an online photo album.
GeekTool installs as a preferences panel, and is easy to configure. You can create groups that specify sets of data that it will display, as well as set font colours, styles and positioning. Images can be displayed at different transparencies, in any of nine grid positions. Their refresh time is set in seconds.