In one of The Girl With The Dragon Tattoo movies (I think the Swedish one) during a "hacker scene" Lisbeth had a terminal open on her Mac and it looked like it was just the output of
ls -R on a Linux system (maybe they used
ssh to make it go slower) (and yes, I mean Linux, because I don't think Mac OS X has aspell libraries).
Personally, I would try the output of compiling something from source, preferably something with some dependencies. You can probably use your package management system for this, but I don't know what distro you're using. I used to run a Gentoo system and even though compiling something like OpenOffice.org (as we used then) or Firefox from source took a long time, I still get a warm hacker-feeling from watching something compile.
Something else you might try is the console output from an IRC client. Not the chat rooms themselves but the output from the server with all the archaic control messages and the MOTD's and such. Especially if the feeling you're going for is hacker communications and not just hacker computer program output.
If you want to be super-authentic (à la The Matrix Reloaded, I'd suggest downloading Kali Linux and set up a box to hack into, or at least use
nmap and some SQL database, but pretty much anything done on the command line looks l33t to the masses.