Unix Shells: Bash, Fish, Ksh, Tcsh, Zsh - Hyperpolyglot
Frederic Brodbeck

grammar | quoting and escaping | characters variables | variable expansion | brace, tilde, command, and pathname expansion | special variables arithmetic and conditional expressions arrays | associative arrays functions | command resolution | arguments and options execution control redirection | echo and read | files and directories process and job control history | key bindings startup files | prompt customization | autoload