How to Permanently Export a Variable in Linux

How to permanently export a variable in Linux?

You can add it to your shell configuration file, e.g. $HOME/.bashrc or more globally in /etc/environment.
After adding these lines the changes won't reflect instantly in GUI based system's you have to exit the terminal or create a new one and in server logout the session and login to reflect these changes.

How do I permanently add an environment variable?

Edit your ~/.bashrc file and place at the end:

export JAVA_HOME=jdk-install-dir
export PATH=$JAVA_HOME/bin:$PATH

You can even modify /etc/environment if you want it to persist for all users.

Issue with setting environment variables permanently in linux bash

~/.bash_profile is only sourced on login (i.e. after you've typed your username & password) - ~/.bashrc is sourced for interactive non-login shells.

So I'd add the variables into ~/.bashrc (don't forget to source it first if you're running the python script afterwards from the same shell). This way, when you open a new shell, bashrc will be sourced and your environment variables will be available.

Edit:
As others have said in comments .. running an export command in one shell, won't make that variable availble in another shell - you need to add it to your ~/.bashrc to make it avaiable in other shells

How to permanently set $PATH on Linux/Unix

There are multiple ways to do it. The actual solution depends on the purpose.

The variable values are usually stored in either a list of assignments or a shell script that is run at the start of the system or user session. In case of the shell script you must use a specific shell syntax and export or set commands.

System wide

1. /etc/environment List of unique assignments. Allows references. Perfect for adding system-wide directories like /usr/local/something/bin to PATH variable or defining JAVA_HOME. Used by PAM and systemd.

2. /etc/environment.d/*.conf List of unique assignments. Allows references. Perfect for adding system-wide directories like /usr/local/something/bin to PATH variable or defining JAVA_HOME. The configuration can be split into multiple files, usually one per each tool (Java, Go, and Node.js). Used by systemd that by design do not pass those values to user login shells.

3. /etc/xprofile Shell script executed while starting X Window System session. This is run for every user that logs into X Window System. It is a good choice for PATH entries that are valid for every user like /usr/local/something/bin. The file is included by other script so use POSIX shell syntax not the syntax of your user shell.

4. /etc/profile and /etc/profile.d/* Shell script. This is a good choice for shell-only systems. Those files are read only by shells in login mode.

5. /etc/<shell>.<shell>rc. Shell script. This is a poor choice because it is single shell specific. Used in non-login mode.

User session

1. ~/.pam_environment. List of unique assignments, no references allowed. Loaded by PAM at the start of every user session irrelevant if it is an X Window System session or shell. You cannot reference other variables including HOME or PATH so it has limited use. Used by PAM.

2. ~/.xprofile Shell script. This is executed when the user logs into X Window System system. The variables defined here are visible to every X application. Perfect choice for extending PATH with values such as ~/bin or ~/go/bin or defining user specific GOPATH or NPM_HOME. The file is included by other script so use POSIX shell syntax not the syntax of your user shell. Your graphical text editor or IDE started by shortcut will see those values.

3. ~/.profile, ~/.<shell>_profile, ~/.<shell>_login Shell script. It will be visible only for programs started from terminal or terminal emulator. It is a good choice for shell-only systems. Used by shells in login mode.

4. ~/.<shell>rc. Shell script. This is a poor choice because it is single shell specific. Used by shells in non-login mode.

Notes

GNOME on Wayland starts a user login shell to get the environment. It effectively uses the login shell configurations ~/.profile, ~/.<shell>_profile, ~/.<shell>_login files.

Man pages

• environment
• environment.d https://linux.die.net/man/1/environment.d
• bash
• dash

Distribution-specific documentation

• Ubuntu
• Arch Linux

Related

Difference between Login Shell and Non-Login Shell?

Environment variable change in shell but won't export

Some terminal emulator doesn't run new tabs as login shell. E.g. in Gnome Terminal You should:

1. List item
2. Go to Edit -> Profile Preferences.
3. Select the Title and Command tab. Notice how the Run command as login shell checkbox is unchecked! Check it.

Furthermore setting a variable in a shell session does not make it permanent for later sessions. E.g. exporting a variable makes it available for any further processes that's got created from the actual session.

To make it somewhat permanent You have to add it to e.g. .bashrc

Do note:

Shell config files such as ~/.bashrc, ~/.bash_profile, and ~/.bash_login are often suggested for setting environment variables. While this may work on Bash shells for programs started from the shell, variables set in those files are not available by default to programs started from the graphical environment in a desktop session.

Quoted from the Ubuntu help.

So to decide where to add it please read the fine manual

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