# 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
```