2.9 KiB
Persistent variables shell
Environment variables are a per process thing. So something needs to store the state to disk and load it in to it's environment and pass that environment on to it's child processes.
This is generally done by the shell, I don't think there is a cross shell way to tell a shell to persist an environment variable to it's configuration.
https://help.ubuntu.com/community/EnvironmentVariables
Persistent environment variables
The names of environment variables are case sensitive.
It is a common practice to name all environment variables with only English capital letters and underscore (_) signs.
Note: The shell techniques explained in the following sections apply to the Bourne Shell family of command line shells, which includes sh, ksh, and bash, which is the default shell shipped with Ubuntu. The commands may be different on other shells such as csh.
System-wide environment variables
Environment variable settings that affect the system as a whole (rather than 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.
Note: Any variables added to these locations will not be reflected when invoking them with a sudo command, as sudo has a default policy of resetting the Environment and setting a secure path (this behavior is defined in /etc/sudoers). As a workaround, you can use "sudo su" that will provide a shell with root privileges but retaining any modified PATH variables.
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 than 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.
Note: Some systems now use an envvar.sh placed in the /etc/profile.d/ directory to set system wide environment strings.
Session-wide environment variables
Environment variable settings that should affect just a particular user (rather than the system as a whole) should be set into:
~/.pam_environment - This file is specifically meant for setting a user's
environment. It is not a script file, but rather consists of assignment
expressions, one per line.
PATH DEFAULT=${PATH}:${HOME}/MyPrograms
Note: Using .pam_environment requires a re-login in order to initialize the variables. Restarting just the terminal is not sufficient to be able to use the variables.
If you are using KDE, see http://userbase.kde.org/Session_Environment_Variables/en