• Ref: http://dir.yahoo.com/Computers_and_Internet/Software/Operating_Systems/Unix/Shells/

• What is the Shell?
  • command interpreter
  • process controller
  • user environment customization
  • programming language
• Different Unix Shells:
  • Bourne Shell (/bin/sh)
  • Korn Shell (/bin/ksh)
    • ksh88
    • ksh93
    • pdksh
  • GNU Bourne-Again Shell (/bin/bash)
  • C Shell (/bin/csh)
  • Enhanched C Shell (/bin/tcsh)
  • (etc...)
• Notes:
  • All Unix shells share broad functionalities...
  • But if they weren't different, they'd have the same names.
  • Gauss user shells default to Korn shell;
  • Programming shell (by request): Bourne shell.
• Example customization:

  $ PS1='$ ' $ EDITOR=emacs $ pine $ PATH=/usr/local/bin:$PATH $ pine

• Things to note:
  • Unix Is CaSe SensItiVe!
  • No whitespace around =, apostrophe's, not "double quotes"
  • Left/Right arrows, DEL/ctrl-D/ctrl-U for intraline editing
  • Up/Down arrows for history recall
  • Interactive customizations only work for the current session.
• Commands

  $ who $ whom $ who am i $ who are you $ who -h

• Things to note:
• General syntax: cmd arg1 arg2 arg3 ...
• Whitespace around words ignored
• Option args (often) preceded by hyphen
• echo

  $ echo one two three $ echo "one two" three $ echo My prompt is $PS1 $ echo "My prompt is $PS1" $ echo 'My prompt is $PS1' $ echo My prompt is \$PS1 $ echo My prompt is \\$PS1 $ echo "My path is > $PATH"

• Things to note:
  • Quoting whitespace
  • Difference between apostrophe's and "quotes".
  • Shell variable interpolation (bare or "quotes")
  • Multiline commands
  • Shell metacharacters (space, equals, apostrophe, quotes, dollar, backslash)
  • Others we'll see (asterisk, question mark, parens, vertical bar, lessthan, greaterthan, backtick, ...)

On to Filesystem Basics