How do I set an environmental variable for a GNOME session?

Question

On my system, for apps that use SDL, I need to set an environmental variable:

export SDL_AUDIODRIVER=alsa

to get the sound to work properly. How do I set up my GNOME session so that this variable is present for all applications (so if I run an application through Nautilus, or use DBGL, the apps work properly)?

EDIT:

Configuration files I have set (and reset my machine after each) to no avail:

• .xsession
• .xsessionrc
• .gnomerc
• .bash_profile
• .profile<-- This works in the general case, but not when your distro is setting the variable elsewhere.
• /etc/profile

Answer 1

It could be that the SDL_AUDIODRIVER variable is being unset somewhere. One strategy I use for problems with things related to startup scripts is to put in debug echo statements that is simple to enable/disable by creating/deleting a file. You could start by adding

debug_msg() {
        test -f $HOME/.debug && echo "$@" 1>&2
}

debug_msg "running ~/.bashrc ($0), SDL_AUDIODRIVER = '$SDL_AUDIODRIVER'"

to .bashrc, .bash_profile, .profile and /etc/profile to see what value it has and if/where it is changing.

Answer 2

https://help.ubuntu.com/community/EnvironmentVariables talks about four places where we can set the environment variables:

• ~/.pam_environment - […] It is not a script file, but rather consists of assignment expressions, one per line. […] requires a re-login in order to initialize the variables. […]
• ~/.profile - This is probably the best file for placing environment variable assignments, since it gets executed automatically by the DisplayManager during the start-up 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.

http://userbase.kde.org/Session_Environment_Variables/en suggests this place for KDE:

KDE will execute any script it finds in $HOME/.kde/env whose filename ends in .sh, and it will maintain all the environment variables set by them. It is important that any variable you want to set must be also exported.

https://help.ubuntu.com/community/ComposeKey#XIM suggests modifying ~/.gnomerc or ~/.Xsession.

Answer 3

Create a .gnomerc file in your $HOME which is a shell script (like .bashrc) which sets all the variables you want.

Answer 4

Have you tried creating the environment variable int .profile or /etc/profile?

That should work and should already exist. Unlike .bashrc which is per terminal session, these are initiated at login to your session.

Answer 5

Some answers do not apply to Gnome. Some others may not work now.

See Definition of user service environment.

You can create (for yourself) a file like ~/.config/environment.d/*.conf and define variables therein.

Example (for all users)

% more /etc/environment
#
# This file is parsed by pam_env module
#
# Syntax: simple "KEY=VAL" pairs on separate lines
#

EDITOR=/usr/bin/nano

From man pam_env:

PAM_ENV(8)                     Linux-PAM Manual                     PAM_ENV(8)

NAME
       pam_env - PAM module to set/unset environment variables

This will set environment at login, update needs logout login.

It will work with Gnome but is apparently more generally linked to systemd.

From Wikipedia:

systemd is a software suite that provides an array of system components for Linux operating systems. The main aim is to unify service configuration and behavior across Linux distributions. Its primary component is a "system and service manager" — an init system used to bootstrap user space and manage user processes.