Unix / Linux Shell - The if...else...fi statement
The if...else...fi statement is the next form of control statement that allows Shell to execute statements in a controlled way and make the right choice.
if [ expression ] then Statement(s) to be executed if expression is true else Statement(s) to be executed if expression is not true fi
The Shell expression is evaluated in the above syntax. If the resulting value is true, given statement(s) are executed. If the expression is false, then no statement will be executed.
The above example can also be written using the if...else statement as follows −
#!/bin/sh a=10 b=20 if [ $a == $b ] then echo "a is equal to b" else echo "a is not equal to b" fi
Upon execution, you will receive the following result −
a is not equal to b