Look, it's eshell!
Josh Nimoy wrote about his special effects contributions, among others, to Tron: Legacy:
I spent a half year writing software art to generate special effects for Tron Legacy, working at Digital Domain with Bradley "GMUNK" Munkowitz, Jake Sargeant, and David "dlew" Lewandowski. [...]
In addition to visual effects, I was asked to record myself using a unix terminal doing technologically feasible things. I took extra care in babysitting the elements through to final composite to ensure that the content would not be artistically altered beyond that feasibility. I take representing digital culture in film very seriously in lieu of having grown up in a world of very badly researched user interface greeble. [...] In Tron, the hacker was not supposed to be snooping around on a network; he was supposed to kill a process. So we went with posix kill and also had him pipe ps into grep. I also ended up using emacs eshell to make the terminal more l33t. The team was delighted to see my emacs performance -- splitting the editor into nested panes and running different modes. I was tickled that I got emacs into a block buster movie.
I previously wrote that
the filmmakers should win some sort of award for Not Totally Outrageous Use Of Unix In A Hollywood Movie. Whoever is responsible, I salute you.
So I guess we now know how that transpired and who is responsible for (part of) it.
(via Romain Francoise)