How to Print Env Variable Linux [5 Best Methods]

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Ojash

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Akshat

Last updated: June 6, 2024

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Have you ever had trouble getting your programs to find the right files or configurations? Environment variables can solve this problem by storing critical information that your computer uses to manage applications and scripts. In this post, I’ll show you how to print environment variable Linux using commands like printenv, env, echo, and declare. You’ll also learn some best practices for managing these variables. By the end of this guide, you’ll have the skills to efficiently manage your system’s environment variables and troubleshoot any related issues confidently.

What are Environment Variables?

Environment variables are like small notes you leave for your computer to tell it how to behave. They store information that different programs and scripts can use. For example, they can tell your computer where to find certain files or how to display text.

Environment variables are important because they:

• Help programs find files: By setting variables like PATH, you can tell your computer where to look for programs you want to run.
• Customize your environment: You can set variables to change the behavior of your system and applications without modifying the code.
• Improve efficiency: Instead of setting the same configuration repeatedly, you can use environment variables to set them once and apply them everywhere.
• Ensure consistency: They provide a consistent way to manage settings across different programs and scripts.

How to Print Env Variable Linux

Keep reading for the detailed steps for five different methods to print environment variables:

1.  printenv Command

The printenv command is a simple yet powerful tool to print environment variables in Linux. It provides a quick overview of all variables, aiding efficient system inspection and troubleshooting. Follow these steps:

1. Open your Terminal window.

2. To Linux print all environment variables, type:

printenv

3. This will provide a comprehensive list of all environment variables set in your Linux system.

4. If you need to print specific variables, use the -u flag followed by the variable name, like this:

printenv -u PATH

5. This command will display the value of the PATH variable, or any other variable you specify after the -u flag.

2. env Command

The env command is similar to printenv but excels in executing commands with custom environments. It allows for a more dynamic approach to setting variables while running specific commands, making it a preferred choice for developers. Here is the step-by-step guide:

1. To display all environment variables using env, open the Terminal and type:

env

2. This will show a list of all environment variables set in your system.

3. You can also use env to run commands with custom environment settings:

env VAR=value command

Replace VAR with the variable name, value with the desired value, and command with the actual command you want to execute.

4. By default, the script will print Hello if the GREETING environment variable is not set.

3. echo Command

The echo command is a built-in shell command that enables quick display of specific variables. Ideal for debugging and script development, it offers a straightforward method to view single variables at a glance. Follow these steps:

1. To print a specific variable, use $ followed by the variable name, like this:

echo $PATH

2. This command will display the value of the PATH variable, or any other variable you specify after the $ symbol.

4. declare Command

The declare command offers advanced control over variable properties, making it invaluable for managing complex variables and their attributes. Here is how to do it:

1. To display all environment variables using declare, open the Terminal and type:

declare

2. This will show a list of all environment variables along with their attributes.

3. You can use various options with declare to customize variable behavior:

• Use -p to display variable attributes, showing additional information about each variable.
• Use -x to mark variables for export, making them available to child processes.
• Use -g to create global variables, which are accessible across different shell sessions.

5. Scripting to Print Variables

Scripting empowers advanced users to automate variable display and manipulate output formats. Ideal for customizing variable extraction in complex scenarios. Follow these steps:

1. Create a Bash script to display variables. For instance, a Bash script to print all variables would look like this:

#!/bin/bash
printenv

2. Save the above script in a file with a .sh extension, such as variables.sh.
3. To execute the script, navigate to its location in the Terminal and run the following command:

./variables.sh

4. This will execute the script and display all environment variables in your Linux system.

How to Create Environment Variables on Linux

Creating environment variables in Linux is a fundamental task that allows you to set up custom variables to store configuration settings, paths, and other data that different applications and scripts can use. This is particularly useful for setting up development environments, specifying configuration options, and managing system behavior dynamically.

1. Press Ctrl + Alt + T to open the terminal.
2. Type the following command to create a temporary environment variable:

export MY_VAR="my_value"

This command sets MY_VAR to “my_value” for the current terminal session. It will not persist after you close the terminal.

3. To verify the environment variable, run:

echo $MY_VAR

4. Press Enter.

5. Open the ~/.bashrc file in a text editor (e.g., nano):

nano ~/.bashrc

6. Add the following line at the end of the file:

export MY_VAR="my_value"

7. Save and close the file (for nano, press Ctrl + X, then Y, and Enter).

8. To apply the changes, type:

source ~/.bashrc

This command reloads the .bashrc file, applying the new environment variable for all future terminal sessions.

How to Delete Environment Variables on Linux

Deleting environment variables in Linux is necessary when a variable is no longer needed or if it contains sensitive information that should not persist. Properly removing unused environment variables helps maintain a clean and secure system environment.

1. Open Terminal. Type the following command to unset (delete) a temporary environment variable:

unset MY_VAR

This command removes MY_VAR from the current terminal session.

2. To verify that the environment variable has been deleted, type:

echo $MY_VAR

No output (blank line), indicating that MY_VAR is no longer set.

3. Open the ~/.bashrc file in a text editor (e.g., nano):

nano ~/.bashrc

4. Locate the line that sets the environment variable. Delete or comment out this line (by adding # at the beginning):

#export MY_VAR="my_value"

5. Save and close the file (for nano, press Ctrl + X, then Y, and Enter).

6. To apply the changes, type:

source ~/.bashrc

This command reloads the .bashrc file, ensuring that the environment variable is no longer set in future terminal sessions.

5 Best Practices to Print Environment Variables in Linux

Printing environment variables in Linux is critical for system administrators and developers. Adopting best practices will empower you to confidently navigate the world of environment variables in Linux. Efficiently print and manage variables, troubleshoot issues, and optimize your system for peak performance. Here are five best practices to master this essential skill:

• 🔍 Use printenv for Quick Overview: The printenv command displays all environment variables at once, providing a quick overview of system configurations. It’s popular for its efficiency and simple syntax, allowing rapid information retrieval directly from the Terminal.
• 📝 Document Customized Variables Properly: Keep detailed documentation of customized environment variables, including their purposes and side effects. Proper documentation helps track changes, aids understanding, and simplifies sharing and collaboration.
• ⚡ Use echo for Specific Variables: To print a specific variable’s value, use echo followed by the variable name (e.g., echo $VARIABLE). Be cautious with special characters in variable values to avoid output issues.
• 🖥️ Leverage GUI Tools for User-Friendly Exploration: GUI tools like System Monitor provide an intuitive interface to visualize and monitor environment variables. These tools are especially useful for beginners and desktop users, enhancing their Linux experience.
• 🧰 Consider External Tools for Advanced Control: External tools like env-var or dotenv offer advanced features such as variable manipulation, encryption, and integration with other tools. They are beneficial for complex systems requiring granular control over environment variables, boosting productivity and workflow.

Linux Print Env Variable: Wrapping Up

In this article, I have explored various methods to Linux print environment variables using commands like printenv, env, echo, and declare, along with scripting techniques.

For further reading, I recommend:

• Checking out how to prettify JSON in the command line, which can improve your data management and visualization skills.
• Exploring ways to use the grep OR,AND, and NOT condition to search for specific environment variable values within files and outputs.
• Understanding how to use the read command in Linux for better user input handling in your scripts.

Frequently Asked Questions