How do I delete an exported environment variable?

unset is the command you're looking for.

unset GNUPLOT_DRIVER_DIR

Walkthrough of creating and deleting an environment variable in Bash:

Test if the DUALCASE variable exists (empty output):

env | grep DUALCASE

It does not, so create the variable and export it:

DUALCASE=1
export DUALCASE

Check if it is there:

env | grep DUALCASE

Output:

DUALCASE=1

It is there. So get rid of it:

unset DUALCASE

Check if it's still there (empty output):

env | grep DUALCASE

The DUALCASE exported environment variable is deleted.

Extra commands to help clear your local and environment variables:

Unset all local variables back to default on login:

CAN="chuck norris"
set | grep CAN

Output:

CAN='chuck norris'

env | grep CAN # Empty output

exec bash
set | grep CAN
env | grep CAN # Empty output

exec bash command cleared all the local variables, but not environment variables.

Unset all environment variables back to default on login:

export DOGE="so wow"
env | grep DOGE

Output:

DOGE=so wow

env -i bash
env | grep DOGE # Empty output

env -i bash command cleared all the environment variables to default on login.

The original question doesn't mention how the variable was set, but:

In C shell (csh/tcsh) there are two ways to set an environment variable:

1. set x = "something"
2. setenv x "something"

The difference in the behaviour is that variables set with the setenv command are automatically exported to a subshell while variables set with set aren't.

To unset a variable set with set, use

unset x

To unset a variable set with setenv, use

unsetenv x

Note: in all the above, I assume that the variable name is 'x'.

Credits:

• TCSH / CSH: set vs setenv Command Differences

• set, unset, setenv, unsetenv, export — Shell Environment Variable Built-in Functions

This may also work.

export GNUPLOT_DRIVER_DIR=

As mentioned in the above answers, unset GNUPLOT_DRIVER_DIR should work if you have used export to set the variable. If you have set it permanently in ~/.bashrc or ~/.zshrc then simply removing it from there will work.

On Linux and macOS, you can use the command unset to remove an environment variable.

unset GNUPLOT_DRIVER_DIR

Remove the variable permanently,

In Linux

You can edit your shell profile file, such as .bashrc or .bash_profile in the /etc/profile.d directory and remove the line that exports the variable.

.bashrc file:

nano ~/.bashrc

Then, search for the line export GNUPLOT_DRIVER_DIR and delete it. Then save the file.

In Windows

use the setx command to delete an environment variable.

setx GNUPLOT_DRIVER_DIR ""

You can find more information about environment variables and how to manage them in the following links:

• Linux: https://www.cyberciti.biz/faq/set-environment-variable-linux/

• Windows: https://www.computerhope.com/issues/ch000549.htm

LINUX

First find which script file defines and adds the variable to the environment.

Look in /etc files like profile, bash.bashrc, .bashrc, .bashrc_login, etc

And look in similarly named files in the user's home directory.

If it's not in any of those, it's likely that it's in some script file that was part of an installed package. For example, the package SDKMAN (for managing alternate SDK versions) creates a variable called DERBY_HOME. To find the script file creating it, apply the following search command to the /etc folder:

$ sudo egrep -lir THE_VAR_NAME /etc

This should produce some output like:

/etc/profile.d/jdk.sh
/etc/profile.d/jdk.csh

The separate file jdk.csh is needed for the C-shell environment if users have defaulted to it.

Once found it is simply a matter of navigating to the folder containing the script files, in this case here /etc/profile.d/ and then editing the files (with admin permission), removing the variable assignments and saving:

$ cd /etc/profile.d/

$ sudo gedit jdk.sh

$ sudo gedit jdk.sh

Of course, in this case the package setting the env variable is in use so I kept it.

But if the package were not in use and the env vars dead weight to the startup process, then it should be deleted.

WINDOWS

Use the process shown in this YouTube video.