csh (C shell from BSD) The C shell was originally written at UCB to overcome limitations in the Bourne shell. Its flexibility and comfort (at that time) quickly made it the shell of choice until more advanced shells like ksh, bash, zsh or tcsh appeared. Most of the latter incorporate features original to csh. This build is based on OpenBSD sources from 2011. For Slackware-specific details about this build of csh, see the file README_Slackware.txt. Seriously, really, read it.