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What Are Environment Variables in Linux?<\/h2>\n
Linux distributions have environment and shell variables, which function similarly but have different scopes.<\/p> Environment variables have a global scope, accessible in all shell sessions, child processes, and other programs. They may apply to a specific user or all accounts within a system.<\/p> Meanwhile, shell or local environment variables only apply to the current session in which they are created. You can’t use them on sub-shells, other processes, or different accounts.<\/p> In this section, we will explain how to check environment variables in Linux. For a remote system like a virtual private server<\/a> (VPS), connect using an SSH client like PuTTy<\/a> or Terminal.<\/p> \n\n\n Hostinger offers a Browser<\/strong> terminal feature for executing commands and managing system variables in Linux servers via web browsers. In addition to convenience, this tool is useful when users disable SSH for security reasons.<\/p>\n <\/div>\n\n\n\n<\/p> To list all environment variables in Linux, run the printenv <\/strong>command without any options or flags:<\/p> By default, Terminal will print all the environment variables and their values, making the output very long. Add the less <\/strong>modifier to simply the list:<\/p> You can also use env<\/strong>, which <\/strong>works similarly to printenv<\/strong>. Meanwhile, the set <\/strong>command prints shell and environment variables.<\/p> If you want to show only Linux shell variables of the current user, use grep <\/strong>to filter the output.<\/p> In popular Linux distributions<\/a>, some of the most common environment variables include:<\/p> These special variables have pre-defined purposes and roles. However, you can set user-defined ones to configure your system based on your needs.<\/p> Use the echo<\/strong> command<\/a> to print a single environment variable value. Here’s the syntax:<\/p> Consider the capitalization since this command is case-sensitive. For example, enter the following to retrieve the PATH <\/strong>environment <\/strong>variable value:<\/p> Alternatively, use the printenv command with the variable you want to look up. For instance, run the following to check the HOME<\/strong> environment variable value:<\/p> You can also apply the grep<\/strong> command to check if an entry exists. For example, run the command below to search the USER<\/strong> variable:<\/p> To query multiple environment variables’ values, list them after the printenv<\/strong> command like:<\/p> Use the export <\/strong>command to temporarily set a global environment variable in a Linux operating system. Here’s the syntax:<\/p> Replace VAR <\/strong>with the variable name you want to modify and value <\/strong>with its new value. For example, run the following command to set a new user’s home directory:<\/p> The output should change if you print the HOME <\/strong>variable value using the echo <\/strong>command. You can also set multiple values using a semicolon like the following:<\/p> Remember, this command only applies the new global variable for the current environment. Moreover, the changes will reset after you reboot the system.<\/p> To set a local environment variable, specify the value directly into the command-line interface using this syntax:<\/p> Use all lowercase letters to distinguish it from the global variable and avoid overlaps. If you enter a sub-shell using the bash <\/strong>command, printing the value will give an empty output.<\/p> \n\n\n We recommend using the temporary environment variables for tasks like debugging or testing since it won’t affect other shell processes.<\/p>\n <\/div>\n\n\n\n<\/p> Modify the shell-specific configuration files to make your environment variables persistent. However, the file to edit depends on whether you want to change user-specific or system-wide configuration.<\/p> User-specific Environment Variables<\/strong><\/p> Edit the ~\/.bashrc <\/strong>to only set a permanent environment variable for the current user. To do so, open it using a text editor like nano<\/a>:<\/p> Add the key-value pair at the beginning or bottom of the file for better organization. Here’s the syntax:<\/p> Press Ctrl+X<\/strong>, Y<\/strong>, and Enter<\/strong> to close nano and save the changes. Refresh the current shell session to apply the new configuration using this command:<\/p> Instead of ~\/.bashrc<\/strong>, modify the ~\/.profile <\/strong>file if you want to set variables for login shells.<\/p> Note that you can also modify the shell functions through the ~.\/bashrc<\/strong> file.<\/p> System-wide Environment Variables<\/strong><\/p> To set permanent environment variables that apply to all users within an operating system, edit the \/etc\/environment <\/strong>file using a text editor:<\/p> Add the key-value pairs to the file using the basic syntax without export<\/strong>:<\/p> Save the file and close nano<\/strong>. To apply the changes, re-login your current user or restart the system using the reboot <\/strong>command. The configuration will load whenever you enter the bash login shell<\/p> In addition to the \/etc\/environment <\/strong>file, you can add the environment variable to the \/etc\/profile.d<\/strong> directory. To do so, navigate to the folder using this command:<\/p> Create a new shell script file to store your new global variable using the nano<\/strong> text editor:<\/p> Replace global_env <\/strong>with your desired name, preferably a descriptive one, to simplify identification. In nano<\/strong>, write your environment variables using this syntax:<\/p> Save the changes and close the text editor. Reboot your system to apply the settings to the bash shell.<\/p> If you run the printenv <\/strong>command, the new configuration should show in your Linux environment variables list.<\/p> Use the unset <\/strong>command to remove an environment variable in Linux. Here’s the syntax:<\/p> Replace VAR <\/strong>with the variable you want to delete. Remember that the removal only applies temporarily, meaning the key-value pairs will return after the system reboots.<\/p> To permanently remove an environment variable, open your ~\/.bashrc <\/strong>or \/etc\/environment <\/strong>configuration file using a text editor. Remove the corresponding line and save the changes.<\/p> Instead of deleting, we recommend adding a hash symbol (#<\/strong>) at the beginning of the string to deactivate it. You can quickly reactivate the environment variable by removing the character when the change causes an error.<\/p> Environment variables let you easily set up different areas than the code bases to store sensitive information for your applications. It helps improve security since administrators can limit their access to specific users.<\/p> In addition, using environment variables in shell scripts helps simplify the automatic deployment process. Instead of manually writing information like API URLs in each .sh <\/strong>file, simply export them to apply the value.<\/p> Moreover, it simplifies application management and development since you don’t need to modify the code base frequently. For example, we set two different API URLs as environment variables:<\/p> We call the PYAPP_ENV <\/strong>environmental variable into the application’s code base. During the deployment, we can change its value temporarily into DEPLOY<\/strong>, applying the PYAPP_DEPLOY_API<\/strong>.<\/p> Having several variables saves time, as you don’t need to update them individually when moving the application to another development stage.<\/p> In this section, we will explore the best Linux environment variable practices to help you manage your server easily and securely.<\/p> Use Kodee for Easy Environment Variables Management<\/strong><\/p> All Hostinger VPS hosting plans<\/a> include Kodee<\/strong>, an AI assistant that lets you quickly generate commands or instructions using simple prompts.<\/p> To access the tool, open hPanel <\/strong>and click VPS <\/strong>on the top menu. Select the corresponding server and click Kodee <\/strong>from the sidebar.<\/p> It will write the configurations for setting Linux environment variables, which you can quickly copy-paste to the Browser terminal.<\/p> For example, ask Kodee<\/strong>, “I need to generate a script to set environment variables for my project. I need three variables: ‘API_KEY<\/strong>’ with ‘123<\/strong>’ value, ‘DB_URL<\/strong>’ with ‘https:\/\/example.tld\/database<\/strong>’ value, and ‘LOG_LEVEL<\/strong>’ with ‘debug<\/strong>’ value. Write the Bash script for me.”<\/p>
\nEnvironment variables are dynamic values determining the behavior of shells and processes in a Linux system. Using them, admins can easily set default settings and share configurations between applications for more efficient management.
\nUsers can view all the environment variables with their values using the printenv<\/strong> command and set new ones with the export<\/strong> utility.<\/p>\n <\/div>\n\n\n\n<\/p>How to Manage Linux Environment Variables<\/h2>
Pro Tip<\/h4>\n
How to List Environment Variables in Linux<\/h3>
printenv<\/pre>
![\"The](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/12\/The-printenv-command-lists-all-system-environment-variables-1024x360.png\")
<\/a><\/figure><\/div>printenv | less<\/pre>
\n
How to Print Environment Variables in Linux<\/h3>
echo<\/code> $VARIABLE<\/pre>echo $PATH<\/pre>
![\"The](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/12\/The-echo-command-prints-the-current-value-of-the-PATH-variable-1024x43.png\")
<\/a><\/figure><\/div>printenv HOME<\/pre>
printenv | grep USER<\/pre>
printenv VAR1 VAR2<\/pre>
How to Set Environment Variables in Linux<\/h3>
export VAR=\"value\"<\/pre>
export HOME=\"\/etc\/another\/path\"<\/pre>
export VAR=\"value1:value2\"<\/pre>
![\"The](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/12\/The-export-command-sets-two-values-for-an-environment-variable.png\")
<\/a><\/figure><\/div>var=\"value\"<\/pre>
Pro Tip<\/h4>\n
How to Make Persistent Environment Variables in Linux<\/h3>
sudo nano ~\/.bashrc<\/pre>
export VAR=\"VALUE\"<\/pre>
![\"New](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/12\/New-environment-variables-in-the-bashrc-file-1024x215.png\")
<\/a><\/figure><\/div>source ~\/.bashrc<\/pre>
sudo nano \/etc\/environment<\/pre>
VAR=\"VALUE\"<\/pre>
![\"The](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/12\/The-new-environment-variable-in-the-environment-configuration-file-1024x75.png\")
<\/a><\/figure><\/div>sudo cd \/etc\/profile.d<\/pre>
sudo nano global_env.sh<\/pre>
export VAR=\"VALUE\"<\/pre>
How to Delete Environment Variables in Linux<\/h3>
unset VAR<\/pre>
![\"A](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2023\/12\/A-hash-symbol-disabling-an-environment-variable-in-the-environment-configuration-file-1024x98.png\")
<\/a><\/figure><\/div>Linux Environment Variables in Development<\/h2>
export PYAPP_ENV=\"TEST\"\n\nexport PYAPP_TEST_API=\"https:\/\/api.domain.tld\/\"\n\nexport PYAPP_DEPLOY_API=\"https:\/\/api2.domain.tld\/\"<\/pre>
Linux Environment Variables Best Practices<\/h2>
![\"Kodee](\"https:\/\/www.hostinger.com\/tutorials\/wp-content\/uploads\/sites\/2\/2024\/10\/set-environment-variables-bash-script-generated-by-kodee-1024x495.png\")
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