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# Unix - Shell String Operators Example

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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