UNIX/LINUX SHELLS
“A Unix shell is a command-line interpreter or shell that provides a traditional user interface for the Unix operating system and for Unix-like systems.”
“Users direct the operation of the computer by entering commands as text for a command line interpreter to execute or by creating text scripts of one or more such commands.”
from wikipedia
SHELLS
most popular: sh
written by (Stephen) Bourne shell, 1977 csh
written Bill Joy bash
Bourne Again shell (Unix, Linux, Mac OS)
others: ash, dash, es, fish, ksh, mksh, psh, rc, scsh, tcsh, zoidberg, zsh
SHELLS
WHICH SHELL IS MY DEFAULT SHELL?
When you log in, the shell will load your configuration file (if present).
These files start with a period (.) and should be located in your home directory, (~).
These files are not listed by ls by default. (They are “invisible.”) To have ls list them, use the –a option.
Use .cshrc for csh; use .bashrc for bash.
CONFIGURATION FILES
EXAMPLE .CSHRC
EXAMPLE .BASHRC
setenv (csh) vs. export (bash)
setenv PATH /home/ggrevera/mpich2-install/bin:$PATH
export PATH=/usr/ccs/bin:$PATH
alias (csh) vs. alias (bash)
alias emacs /home/ggrevera/emacs-23.4/src/emacs
alias emacs=/home/ggrevera/emacs-23.4/src/emacs
DIFFERENCES BETWEEN CSH AND BASH
To run a shell, simply type its name. bash
To exit a shell, simply enter the exit command. exit (When you exit your last shell, you will log out of the system.)
HOW DOES ONE RUN/EXIT A SHELL?