tcsh
/tiːˈsiːˌʃɛl/
noun … “an enhanced version of csh with improved interactivity and scripting features.”
C Shell
/siːˈʃɛl/
noun … “a Unix shell with C-like syntax designed for interactive use and scripting.”
csh, short for C shell, is a Unix command-line interpreter developed by Bill Joy in the late 1970s. It introduced a syntax and command structure inspired by the C programming language, making it more familiar to programmers accustomed to C. csh enhanced interactive usability with features such as history substitution, aliases, job control, and built-in arithmetic, while also supporting scripting for automation of system tasks.
ksh
/keɪˈʃɛl/
noun … “a Unix shell that extends sh with advanced scripting and interactive features.”
sh
/ʃɛl/
noun … “the original Unix command interpreter for executing scripts and commands.”
Bash
/bæʃ/
noun … “a Unix shell and command language for interacting with operating systems.”
zsh
/ziː ʃɛl/ or /zɛd ʃɛl/
n. "Extended UNIX shell blending Bourne compatibility with interactive superpowers like spelling correction and recursive globbing."