Linux environment variable configuration example

In the Linux system, environment variables are one of the very important configuration items. They can affect the behavior of the system and the execution of the program. By configuring environment variables, we can customize the behavior of the system to meet our needs. This article will introduce how to configure and use environment variables in a Linux environment, including specific code examples.

What are environment variables?

An environment variable is a value used in the operating system to store dynamic values ​​related to the operating system or user settings. In Linux systems, environment variables are stored in a special area called the environment, and each process can access and use these environment variables.

How to set environment variables?

In Linux systems, you can set environment variables through the export command. For example, to set an environment variable named MY_VAR, you can use the following command:

export MY_VAR=value

Here, MY_VAR is the name of the environment variable, and value is the value of the environment variable. value. With the above command, we set MY_VAR to value.

Sample code:

1. Set a simple environment variable

Let us start with a simple example. Suppose we want to set an environment variable named MY_NAME and set its value to John. We can execute the following command in the terminal:

export MY_NAME=John

2. Using environment variables

Once we set the environment variable, we can use it in various programs. For example, suppose we have a script named test.sh with the following content:

#!/bin/bash

echo "Hello, $MY_NAME!"

In this script, we use the $MY_NAME environment variable. When we run this script, it prints Hello, John!.

For the above script to take effect, you first need to give it execution permission:

chmod +x test.sh

Then execute the script:

./test.sh

You should see the outputHello, John! .

3. Permanently set environment variables

If you want to retain the settings of environment variables after the system is restarted, you can add the environment variables to .bashrc or .bash_profile file. For example, add the following line in the .bashrc file:

export MY_NAME=John

In this way, the MY_NAME environment variable will automatically take effect every time you log in to the system.

Summary

In the Linux system, environment variables are a very useful configuration item that can help us customize the behavior of the system. Through the introduction and sample code of this article, I hope readers can better understand how to set and use environment variables in Linux systems. If you have any questions or suggestions, please leave a message for discussion.

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