The if statement lets you test for a condition. Based on the true (0) or false (1) return of a test, a series of statements can then be performed. The construct of the if statement makes it ideal for error checking. Here’s the format of the if statement:
if condition1 then commands1 elif condition2 then commands2 else commands3 fi
Let’s break down this if statement to see what’s really going on.
|if condition1||If condition1 is true|
|commands1||do the commands1|
|elif condition2||if condition1 is not met|
|commands2||do the commands2|
|else||if condition1 or condition2 is not met|
|commands3||then do commands3|
The if statement must be terminated with the word fi. Leaving out the closing fi ...