What's
A
 

What's
A
CELL  SHELL?

a shell is a user interface for access to an operating system's services.

So what's a Shell Script?

> Command language for shells <

List of SOme SHells

• sh - Shell
• csh - C Shell
• zsh - Z Shell
• ash - Almquish Shell
• dash
• bash - Bourne Again Shell
• psh - Perl Shell
• pwsh - Powershell
• fish - friendly interactive Shell
• eshell
• ksh - korn shell
• nushell
• elvish
• cmd
• rc shell

• nushell
• elvish
• cmd
• rc shell
• scsh - scheme 

But
How Do
They Work?

SHELL Architecture

shell proc

terminal file

read fd

write fd

Using
The SHell...
The RIGHT WAY...?

PATH TO EVERYTHING

$PATH=""/usr/local/bin:/usr/bin:$HOME/.local/bin"

Exports

exporting some VARs

ALIAS

Aliasing some commands