How to use if statement in Shell

In Shell programming, the if statement is a conditional control statement used to execute different code blocks based on the true or false condition. The basic syntax of the if statement is as follows:

if [ condition ]
then
    # code block executed if condition is true
else
    # code block executed if condition is false
fi

Among them, conditionis a conditional expression, which can use comparison operators, logical operators and file test operators to perform conditional judgments.

Below we will introduce the usage of if statement in Shell in detail and illustrate it through sample code.

1. Basic if statement

The simplest if statement only contains a condition and a code block. If the condition is true, the content in the code block is executed, otherwise it is skipped.

if [ $num -gt