Set environmental variable in Ubuntu

https://help.ubuntu.com/community/EnvironmentVariables

Persistent environment variables

So far we've only discussed ways set an environment variable value temporarily until the shell session in which it was set is closed. One may wonder if there is a way to somehow permanently set an environment variable to a certain value.

Note: The shell config files mentioned below are only meant to be read by particular shells and desktop environments and should not be used.

Session-wide environment variables

The below are not recommended but the previous solution (?) provided on this page did not work with the 10.04 desktop release. .pam_environment is not naturally procesed with the distribution.

Not recommended:

• ~/.profile - This is probably the best file for placing environment variable assignments in, since it gets executed automatically by the DisplayManager during the startup process desktop session as well as by the login shell when one logs-in from the textual console.
• ~/.bash_profile or ~./bash_login - If one of these file exist, bash executes it rather then "~/.profile" when it is started as a login shell. (Bash will prefer "~/.bash_profile" to "~/.bash_login"). However, these files won't influence a graphical session by default.
• ~/.bashrc - Because of the way Ubuntu currently sets up the various script files by default, this may be the easiest place to set variables in. The default configuration nearly guarantees that this file will be executed in each and every invocation of bash as well as while logging in to the graphical environment. However, performance-wise this may not be the best thing to do since it will cause values to be unnecessarily set many times.

System-wide environment variables

Environment variable settings that affect the system as a whole (rather then just a particular user) should not be placed in any of the many system-level scripts that get executed when the system or the desktop session are loaded, but into

• /etc/environment - This file is specifically meant for system-wide environment variable settings. It is not a script file, but rather consists of assignment expressions, one per line. Specifically, this file stores the system-wide locale and path settings.

Not recommended:

• /etc/profile - This file gets executed whenever a bash login shell is entered (e.g. when logging in from the console or over ssh), as well as by the DisplayManager when the desktop session loads. This is probably the file you will get referred to when asking veteran UNIX system administrators about environment variables. In Ubuntu, however, this file does little more then invoke the /etc/bash.bashrc file.
• /etc/bash.bashrc - This is the system-wide version of the ~/.bashrc file. Ubuntu is configured by default to execute this file whenever a user enters a shell or the desktop environment.

Note: When dealing with end-user/home desktop systems may be appropriate to place settings in the user's ~/.pam_environment files discussed above rather then the system-wide ones, since those files do not require one to utilize root privileges in order to edit and are easily moved between systems.