brief history

• 1971, thompson shell
• 1973, pwb shell (mashey shell), introduces one-letter variables and pipes
• 1978, csh, c-style scripting (broken), some interactivity, moar followed 1981 with tcsh (completion, interactive history)
• 1979, sh, bourne shell, base for posix
• 1983, ksh, korn shell, bourne w/ interactivity and some more, part of system v, commercial, also influenced posix
• 1989, ash, almquist shell, bsd licensed sh, spawned as dash, busybox
• 1989, bash, same goals as ksh
• 1990, zsh, same goals as ksh

types

login shells

setup only needed once, f.e. run ssh-agent, notify other users (write). usual config files are profile, login and logout. triggered by -l or leading -. can be exitted with logout.

interactive shells

read rc files.

misc

talk with term via stty -a

clean passing of parameters from f.e. find. $0 may also appear in error messages as command name.

sh -c 'echo $0 $1' command_name argument