Shells Shells WildChar

`.login' Profile and `.cshrc'

As you probably remember from the first section, the outermost layer in the UNIX structure is the Shell, or command interpreter. The Shell, however, is simply a program called upon to interpret the commands users type, and as such, there are many different versions of the Shell. The two most widely used shells are the Bourne Shell (sh) and the C-Shell (csh). The shell that you will probably be using is tcsh, an improved version of the older csh (Use the ps command to determine which shell you are using). You can easily switch shells by typing in the name of the desired shell at the prompt (provided that your PATH has been suitably configured).

Besides several cosmetic changes, tcsh offers two important new features:

• Emacs-style command line editing. CTL-p and the up-arrow key recalls the previous command, the left and right-arrow keys allow cursor movement within the line, etc.
• File name and command name completion. Type TAB and tcsh will complete the command or file name as much as possible, making it much quicker to enter long names.

When you log in, your shell will execute a startup file known as `.login'. This file will contain specific commands that you would always want to execute at the beginning of each login session (such as checking for new messages). The `.login' file that the new user gets looks like this:

        [lyman|9] cat .login
        tset -I
        if ( $?DISPLAY ) then
          cat /etc/motd
        endif
        rn -c

To have the date and time echoed at login, just insert the command date; to set certain characters to special meanings use command stty (i.e. stty erase '^H' kill '^U').

Your `.cshrc' is another initialization file that contains directions that you want to be done for every shell (such as setting up aliases for your favorite commands). The typical `.cshrc' file is:

        [lyman|10] cat .cshrc
        setenv EDITOR emacs
        setenv PATH .:$HOME/bin:/usr/lang:/usr/ucb:/bin:/usr/bin:
        /usr/local/bin:/usr/X11R6/bin:/usr/hosts:/usr/games
        setenv MANPATH /usr/lang/man:/usr/man:/usr/local/man
        setenv TEXINPUTS .:$HOME/tex:/usr/local/lib/tex/inputs//
        setenv HOST `hostname`
        set history = 40
        set ignoreeof noclobber notify filec
        if ( `basename $shell` == csh ) then
                set prompt = "[$HOST|\!] "
        else
                set prompt = "[%M|%h] "
        endif
        unset autologout
        umask 022

The PATH setting above is very important since it tells the shell where to look for the programs that you enter as executable commands. Note that the current directory . is searched first, followed by your home `~/bin', and finally various system directories. To set an alias such as having bye mean logout, simply insert alias bye 'logout' in the file.

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