Shell provides if and else to run conditional statements depending upon whether the evaluation is true or false. It is useful if we want to perform certain tasks only if a certain condition is true.
The test condition to if can be given using a test condition or [condition]. We have already learned multiple use cases and examples of testing an expression in the previous section, Testing expressions with a test.
The syntax of the if condition is as follows:
if [ conditional_expression ] then statements fi
If conditional_expression is true—that is, the exit status is 0—then the statements inside it get executed. If not, then it will be just be ignored and the next line after fi will be executed.
The syntax of if and else is as follows:
if [ conditional_expression ] then statements else statements fi
Sometimes, when a condition is not true, we might want to execute some statements. In such cases, use if and else. Here, if conditional_statement...