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Here is an example which uses all the string operatos:
#!/bin/sh a="abc" b="efg" if [ $a = $b ] then echo "$a = $b : a is equal to b" else echo "$a = $b: a is not equal to b" fi if [ $a != $b ] then echo "$a != $b : a is not equal to b" else echo "$a != $b: a is equal to b" fi if [ -z $a ] then echo "-z $a : string length is zero" else echo "-z $a : string length is not zero" fi if [ -n $a ] then echo "-n $a : string length is not zero" else echo "-n $a : string length is zero" fi if [ $a ] then echo "$a : string is not empty" else echo "$a : string is empty" fi |
This would produce following result:
abc = efg: a is not equal to b abc != efg : a is not equal to b -z abc : string length is not zero -n abc : string length is not zero abc : string is not empty |
There are following points to note down:
There must be spaces between operators and expressions for example 2+2 is not correct, where as it should be written as 2 + 2.
if...then...else...fi statement is a decision making statement which has been explained in next chapter.
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