Creating Aliases for the C Shell

Define any aliases for the user in the .cshrc file. The syntax for creating an alias is alias alias-name command sequence. For example, you can shortcut the alias command so that you type only the letter a by adding this line to the .cshrc file:

alias a alias

Here are some examples of aliases from a .cshrc file. Note that if the command contains spaces, you enclose the entire command in quotes. In these examples, both double and single quotes are used:

alias a alias
a h history
a c clear
a lf ls -F
a ll "ls -l | more"
a la ls -a
a s "source .cshrc"
a f 'find ~ -name core -print'
a copytotape "tar cvf /dev/rmt/Ø *"

Setting history for the C Shell

To set history for the C shell, on a command line type set history=n and press Return. history is set to the number of lines you specify:

oak% set history=1Ø
oak%

You can set history temporarily for a shell window or set it "permanently" so that the same history setting is available at each login session by entering the command as a line in your .cshrc file.

Using history for the C Shell

To display the history for the C shell, on a command line type history and press Return. The last n commands that you had set for the history are displayed:

oak% history
    26  pwd
    27  kermit
    28  cd Howto
    29  tar xvf /dev/rmt/Ø
    3Ø  ls -l howto*
    31  cd
    32  cd Config/Art
    33  ls -l
    34  tar cvf /dev/rmt/Ø
    35  history
oak%

To repeat the previous command in a C shell, type !! and press Return. The previous command is executed again:

oak% history
    26  pwd
    27  kermit
    28  cd Howto
    29  tar xvf /dev/rmt/Ø
    3Ø  ls -l howto*
    31  cd
    32  cd Config/Art
    33  ls -l
    34  tar xvf /dev/rmt/Ø
    35  history
oak% !!
history
    27  kermit
    28  cd Howto
    29  tar xvf /dev/rmt/Ø
    3Ø  ls -l howto*
    31  cd
    32  cd Config/Art
    33  ls -l
    34  tar xvf /dev/rmt/Ø
    35  history
    36  history
oak%

To repeat the last word of the previous command in a C shell, type !$ and press Return. The last word from the previous command is used as part of the command-line argument.

For example, you might list the complete path name of a file, and then use the path name as the argument to edit the file using vi, or to print it:

oak% ls -l /home/ignatz/quest
oak% lp !$ lp
/home/ignatz/quest
oak%

You can use the !$ command anywhere within the command line. In this example, the file /home/ignatz/quest is copied to the /tmp directory:

oak% ls -l /home/ignatz/quest
oak% cp !$ /tmp
cp /home/ignatz/quest /tmp
oak%

To repeat a numbered command in a C shell, type !n and press Return. The number in the shell prompt is n. The command is executed again.

oak% history
29  tar xvf /dev/rmt/Ø
3Ø  ls -l howto*
31  cd
32  cd Config/Art
33  ls -l
34  tar xvf /dev/rmt/Ø
35  ls -l
36  cd
37  lp howto*
38  history
oak% !32
cd Config/Art
oak%

Setting the Backspace Key for the C Shell (stty erase)

If you want to change the erase key from Delete to Backspace, type stty erase, then press Control and Shift together, and then type H and press Return. The Backspace key is set as the erase key:

oak% stty erase ^H
oak%

Incorporating a New Command for the C Shell (rehash)

The C shell builds an internal table of commands named with the path variable. When you add a new command to a directory, the command is not part of the internal table and the shell cannot execute it. To incorporate a new command into the search path internal table, type rehash and press Return. Any new commands are incorporated into your command search path:

oak% newcommand
newcommand: Command not found
oak% rehash
oak% newcommand
oak%

Editing C Shell History Commands

You can edit commands retrieved from the history list using the s/oldstring/newstring/ form to substitute in the command as retrieved. In this example, an incorrectly typed command from the history list is corrected:

oak% history
    31  cd
    32  ls
    33  cd /home/frame3.1
    34  ls
    35  cd ..
    36  tar cvf /dev/rmt/Ø frame3.1
    37  lp questionnaire
    38  lpstat -t
    39  echo $PaTH
    4Ø  history
oak% !39:s/a/A/
echo $PATH
.:/home/winsor:/usr/openwin/bin:/usr/deskset/bin:/home/
winsor/bin:/bin:/home/bin:/etc:/usr/etc:/usr/bin:/home/frame3.1/bin
oak%

The Korn Shell

The Korn shell, developed by David Korn of AT&T Bell Laboratories, is a superset of the Bourne shell. That is, the Korn shell uses the same syntax as the Bourne shell, but it has more built-in functions that can be defined directly from the shell. The Korn shell provides a more sophisticated form of command editing than does the C shell. The Korn shell also provides a command history and aliases.

The Korn shell provides a complete command and programming language. The following sections provide a brief introduction to some of the most basic features of the Korn shell.