How to check if a variable is set in Bash Script or Not

If in your bash script, you want to know if a variable is set or not you can make use of the following,

1. The isset function.
2. Usiing the -z option

Let's take a look at each of them with examples.

Example 1: The isset function

#!/bin/bash

isset() {
    [[ -n "${!1}" ]]
}


my_var="Hey there!"
if isset "my_var"; then
    echo "The variable is set."
else
    echo "The variable is not set."
fi

Example 2: Using the -z Option

#!/bin/bash

if [ -z "$no" ]; then
    echo "The variable is not set."
else
    echo "The variable is set."
fi