How to set environment variable for everyone under my linux system?

Solution 1:

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.

Solution 2:

If your LinuxOS has this file:

/etc/environment

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

Extracted from: http://www.sysadmit.com/2016/04/linux-variables-de-entorno-permanentes.html

Solution 3:

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).

Solution 4:

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.

Solution 5:

Some interesting excerpts from the bash manpage:

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 environement variable:

export MY_VAR=xxx