C shell
From FreeBSDwiki
(Redirected from Csh)
/bin/csh is where you'll find the binary of the C shell, so called because its syntax is very like the C programming language. It was written by Bill Joy of Sun Microsystems and is the only other shell besides the spartan Bourne shell (/bin/sh) that comes installed by default on a freshly-installed FreeBSD system.
FreeBSD actually uses the tcsh variant of the csh. If you run ls -i /bin/*csh you'll see that /bin/csh is a hardlink to /bin/tcsh (meaning they are actually the same file).
Other shells that you can install and customize for ease of use include the bash, psh, ksh, and zsh shells.