Linux, The case statement, performing different set commands

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The case statement

Instead of nesting many if-then-else or if-then-else-then statements, another alternative is to use the case statement. The case statement allows you to perform a different set of commands depending upon the value associated with a string variable.

Using the case statement

echo -n " What type of pet do you have (dog, cat, etc.)? "

read pet

echo " "

case $pet in

dog) echo " So you have a dog ..."

echo " That's nice, so do I."

echo " My dog's name is Fido.";;

cat) echo " So you have a cat ..."

echo " I'm allergic to cats!";;

fish) echo " So you have fish ..."

echo " Can't take them for a walk .. ha, ha.";;

ferret) echo " Ferrets are cool!";;

*) echo " A $pet ... that's a funny pet";;

esac

echo " "

The case example script above asks the user what kind of pet they have and then provides different responses depending upon the type of pet answered. It looks for answers of “dog”, “cat”, “fish”, “ferret”, and “*”. The asterisk (*) matches any other answer supplied by the user. When a match is found by the case statement, all commands are executed until a double semi-colon (;;) is encountered.

When the example above is entered and saved to a file (we’ll learn this in the next chapter) called whatpet.ksh, we can run it as shown below:

Running the case script

$ ./whatpet.ksh

What type of pet do you have (dog, cat, etc.)? moose

A moose ... that's a funny pet

$ ./whatpet.ksh

What type of pet do you have (dog, cat, etc.)? dog

So you have a dog ...

That's nice, so do I.

My dog's name is Fido.

The above book excerpt is from:

Easy Linux Commands
Working Examples of Linux Command Syntax

ISBN: 0-9759135-0-6

Terry Clark

http://www.rampant-books.com/book_2005_1_linux_commands.htm

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