This tutorial will show you how to set environmental variables in Bash/Shell scripts using the export keyword.
Generally, variables declared in Bash/Shell scripts exist only within the scope of that running Bash/Shell script.
To make them available elsewhere, they can be set as an environmental variable – meaning that the variable will be available when executing commands outside of the script on your system – for example, making the variable available from the command line after the script has completed.
The export keyword does this – here’s how to use it.
What is an Environmental Variable
An environmental variable works much like any other variable, but it’s available everywhere – inside scripts, on the command line, and to other running programs.
Your system already has many environmental variables defined – for example, your home directory is available by reading the environmental variable $HOME.
You can view all currently set environmental variables with the env command:
Set Environmental Variables with export
The following script, testScript.sh, sets an environmental variable and then exits:
#!/bin/bash export MY_ENV_VAR="Save the environment!"
Now, when the above script is executed:
The variable MY_ENV_VAR is available after it has been completed. This can be confirmed by running:
The environmental variable has been set and is now available across the system.
The printenv command can also be used to view an environmental variable
Persisting After Reboot
Environmental variables set with export will not persist a reboot of your computer. To permanently set an environmental variable, it must be declared in your ~/.bashrc file.
The ~/.bashrc file is a script that is run each time you log in. By adding your export statements to it, your environmental variables will be added for each session you log in to.
Above, the nano text editor is used to edit the file. Add your export statements to the end of the file, and they’ll be there after you reboot:
export MY_ENV_VAR="Save the environment!"
System-Wide Environmental Variables
These environmental variables will only be there for the current user. If you’re an administrator and you want to make them available to all users and processes, add the lines to the /etc/environment file instead:
sudo nano /etc/environment