It’s similar to vi as both are modal editors with curses interfaces. However, it differs from vi in that it has the same command syntax as ed. For example, in se to escape from append mode, you’d enter a line containing a single period instead of the vi way of hitting the escape key.

se has a long history dating back to the early 1980s. Beginning in 2013, Thomas Cort undertook the task of modernizing the early code and build system to get the software working on recent POSIX operating systems. The code base was straight forward and only used facilities available 25 years prior, and as a result, with a few modifications, it runs on many modern operating systems. Thomas' primary motivation is to preserve this bit of computing history. His goals are to squash any remaining bugs and make se as portable as possible. No major new features will be added.