The Korn shell uses the Bourne shell as
a basis for its features. These shared features include a login
initialization file and variables (a place holder for information used
for customizing the shell). In addition, the Korn shell provides
aliasing, command tracking, command-line editing, and command
substitution. These features allow the user to be more productive. The
initialization file used to store this information is the .kshrc
(Korn shell run control) file and is stored in the user's home
directory.
The default prompt for the Korn shell is the dollar sign ($). The user
can customize their own shell prompt to their liking using the PS1
(Prompt String 1) predefined shell prompt variable (PS1=$). PS1
can include a wide range of expressions such as character strings,
commands, or other variables. Figure
shows several different ways the standard PS1 prompt ($) can be
customized. The variable PS1 is a shell variable. Any change in the
variable setting will remain until the shell is exited or until a subshell is opened. To make the customized prompt available from one
session to the next, place the PS1 variable in the .kshrc file
(covered in Chapter 15).
| Command Format: |
| PS1=value |
- $ PS1="Good morning$ "
- The first example assigns the prompt to a character string. The
prompt is changed from the conventional $ to a greeting (Good
morning) with the $
at the end. The double quotes are necessary because
of the space between 'good' and 'morning.'
- Good morning$ PS1="`uname
-n` !$ "
- This example demonstrates using a command (uname
-n) with the history line number (!) for a unique prompt. This
command causes the prompt to show the name of the host on which you
are working (saturn 41). The back quotes ( ` ) are used to
substitute the output of the uname command instead of interpreting
it literally. Double quotes surround the entire string.
- saturn 41? PS1="$ "
- This example sets the prompt back to the original Korn shell
dollar sign ($) prompt.
- $ PS1="$PWD $"
- In this example, the prompt is customized to reflect the current
working directory. Double quotes surround the string and allow
expansion of the $PWD variable which always keeps track of the
current working directory.
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Lab
Activity
(Adobe
Acrobat Reader, 57 kB) |
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Korn
Shell Features
In
this lab, you will work with the Korn shell to
understand its features and capabilities. You will
work with aliases, history, and re-execution of
commands and custom prompts in this lab. |
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