CODEWITHSUNDEEP
linuxbashunixenvironment-variables
TIMEX
TIMEX

Reputation: 271674

How can I set an environment variable for everyone under my Linux system?

Can I have certain settings that are universal for all my users?

Upvotes: 206

Views: 365674

Answers (7)

user285594
user285594

Reputation:

Using PAM is excellent.

File /etc/security/pam_env.conf

# Modify the display PAM

# BEFORE: $ export DISPLAY=:0.0 && python /var/tmp/myproject/click.py &

# AFTER: $ python $abc/click.py &
DISPLAY  DEFAULT=${REMOTEHOST}:0.0 OVERRIDE=${DISPLAY}
abc   DEFAULT=/var/tmp/myproject

Upvotes: 5

tulipcomp1
tulipcomp1

Reputation: 1341

If your Linux OS has this file:

/etc/environment

You can use it to permanently set environmental variables for all users.

Extracted from: Linux: Variables de entorno permanentes

Upvotes: 134

Pascal Thivent
Pascal Thivent

Reputation: 570315

Some interesting excerpts from the Bash man page:

When bash is invoked as an interactive login shell, or as a non-interactive shell with the --login option, it first reads and executes commands from the file /etc/profile, if that file exists. After reading that file, it looks for ~/.bash_profile, ~/.bash_login, and ~/.profile, in that order, and reads and executes commands from the first one that exists and is readable. The --noprofile option may be used when the shell is started to inhibit this behavior. ... When an interactive shell that is not a login shell is started, bash reads and executes commands from /etc/bash.bashrc and ~/.bashrc, if these files exist. This may be inhibited by using the --norc option. The --rcfile file option will force bash to read and execute commands from file instead of /etc/bash.bashrc and ~/.bashrc.

So have a look at /etc/profile or /etc/bash.bashrc. These files are the right places for global settings. Put something like this in them to set up an environment variable:

export MY_VAR=xxx

Upvotes: 15

ephemient
ephemient

Reputation: 204678

man 8 pam_env

man 5 pam_env.conf

If all login services use PAM, and all login services have session required pam_env.so in their respective /etc/pam.d/* configuration files, then all login sessions will have some environment variables set as specified in pam_env's configuration file.

On most modern Linux distributions, this is all there by default -- just add your desired global environment variables to /etc/security/pam_env.conf.

This works regardless of the user's shell, and works for graphical logins too (if xdm/kdm/gdm/entrance/… is set up like this).

Upvotes: 43

user50049
user50049

Reputation:

Every process running under the Linux kernel receives its own, unique environment that it inherits from its parent. In this case, the parent will be either a shell itself (spawning a sub shell), or the 'login' program (on a typical system).

As each process' environment is protected, there is no way to 'inject' an environmental variable to every running process, so even if you modify the default shell .rc / profile, it won't go into effect until each process exits and reloads its start up settings.

Look in /etc/ to modify the default start up variables for any particular shell. Just realize that users can (and often do) change them in their individual settings.

Unix is designed to obey the user, within limits.

NB: Bash is not the only shell on your system. Pay careful attention to what the /bin/sh symbolic link actually points to. On many systems, this could actually be dash which is (by default, with no special invocation) POSIXLY correct. Therefore, you should take care to modify both defaults, or scripts that start with /bin/sh will not inherit your global defaults. Similarly, take care to avoid syntax that only bash understands when editing both, aka avoiding bashisms.

Upvotes: 6

Kieron
Kieron

Reputation: 11824

As well as /etc/profile which others have mentioned, some Linux systems now use a directory /etc/profile.d/; any .sh files in there will be sourced by /etc/profile. It's slightly neater to keep your custom environment stuff in these files than to just edit /etc/profile.

Upvotes: 146

DigitalRoss
DigitalRoss

Reputation: 146053

Amazingly, Unix and Linux do not actually have a place to set global environment variables. The best you can do is arrange for any specific shell to have a site-specific initialization.

If you put it in /etc/profile, that will take care of things for most posix-compatible shell users. This is probably "good enough" for non-critical purposes.

But anyone with a csh or tcsh shell won't see it, and I don't believe csh has a global initialization file.

Upvotes: 20

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