How to set environment variable in Linux permanently

How to Set Environment Variables Permanently in Linux

Learn the various methods to set environment variables in Linux, ensuring they persist across sessions and reboots for different scopes.

Environment variables are dynamic named values that affect the way processes run on a computer. They can store information like the default text editor, the path to executable files, or system-wide configurations. While you can set them temporarily for a single session, often you need them to persist. This article will guide you through the most common and effective ways to set environment variables permanently in Linux, covering different scopes from user-specific to system-wide.

Understanding Environment Variable Scope

Before diving into the methods, it's crucial to understand the scope of environment variables. Variables can be set for a single shell session, for a specific user, or globally for all users on the system. The method you choose depends on who needs access to the variable and for how long.

flowchart TD
    A[Start]
    A --> B{Variable Scope?}
    B -->|Current Session Only| C[Use `export` command]
    B -->|User-Specific & Persistent| D[Edit `~/.bashrc` or `~/.profile`]
    B -->|System-Wide & Persistent| E[Edit `/etc/environment` or `/etc/profile`]
    C --> F[Variable active until session ends]
    D --> G[Variable active for user's future sessions]
    E --> H[Variable active for all users & future sessions]
    F & G & H --> I[End]

Decision flow for setting environment variables based on scope.

Method 1: User-Specific Permanent Variables

For variables that should only apply to a single user, the best practice is to modify configuration files located in the user's home directory. The most common files are ~/.bashrc, ~/.profile, or ~/.bash_profile.

1. Open the configuration file

Open ~/.bashrc (or ~/.profile) in your preferred text editor. For example, using nano:

2. Add the variable

At the end of the file, add your environment variable using the export command. For example, to set a custom path for a specific application:

3. Save and exit

Save the file and exit the editor. If using nano, press Ctrl+O, then Enter, then Ctrl+X.

4. Source the file

To apply the changes immediately without logging out and back in, source the file:

5. Verify the variable

Check if the variable is set correctly:

nano ~/.bashrc

Opening .bashrc with nano

export MY_CUSTOM_PATH="/opt/my_app/bin"
export EDITOR="vim"

Adding environment variables to .bashrc

source ~/.bashrc

Sourcing .bashrc to apply changes

echo $MY_CUSTOM_PATH
echo $EDITOR

Verifying the set environment variables

Method 2: System-Wide Permanent Variables

For variables that need to be available to all users and all processes on the system, you should modify system-wide configuration files. The most common locations are /etc/environment or files within /etc/profile.d/.

Using /etc/environment

This file is specifically designed for system-wide environment variables. It's read by the pam_env module at login and is not a script, so it doesn't support shell commands like export.

1. Open /etc/environment

Open the file with root privileges:

2. Add the variable

Add your variable in the format KEY="value" on a new line. Do not use export.

3. Save and reboot

Save the file. A reboot is usually required for changes in /etc/environment to take full effect system-wide.

sudo nano /etc/environment

Opening /etc/environment with root privileges

MY_SYSTEM_VAR="This is a system-wide variable"
JAVA_HOME="/usr/lib/jvm/java-11-openjdk-amd64"

Adding system-wide variables to /etc/environment

Using /etc/profile.d/

The /etc/profile script, which is sourced by all login shells, often includes a line to source all scripts within the /etc/profile.d/ directory. This is a clean way to add system-wide variables or execute commands at login without directly modifying /etc/profile.

1. Create a new script file

Create a new .sh file in /etc/profile.d/. The filename should be descriptive, e.g., my_vars.sh:

2. Add variables to the script

Inside this file, use the export command to set your variables.

3. Set permissions

Make the script executable:

4. Reboot or re-login

Log out and log back in, or reboot your system, for the changes to take effect.

sudo nano /etc/profile.d/my_vars.sh

Creating a new script for system-wide variables

#!/bin/bash
export APP_CONFIG_DIR="/etc/app_config"
export PATH="$PATH:/usr/local/bin/custom_scripts"

Adding variables to the system-wide script

sudo chmod +x /etc/profile.d/my_vars.sh

Making the script executable