How do I delete an exported environment variable?
Before installing gnuplot, I set the environment variable GNUPLOT_DRIVER_DIR = /home/gnuplot/build/src . During the installation, something went wrong. I want to remove the GNUPLOT_DRIVER_DIR environment variable. How can I achieve it?
For those looking for how to do this in Fish shell see stackoverflow.com/questions/30703860/… (even though this question isn’t for a specific shell)
7 Answers 7
unset is the command you’re looking for.
but this only works for a session, what about unsetting it definitely? or maybe searching where is the variable set, so you can go and delete it?
This should work per terminal instance. Generally, each time a terminal window is opened, it will load up variables from various places such as ~/.bashrc, ~/.profile, etc. Any variables you set in one terminal instance will not carry over to another. If you have a variable which seems to be set automatically every time you open terminal, try looking through the various hidden files in your home directory for it. Or, to see where it is being set, try «grep -r
This removes the variable from the shell too though. Is the only way to unexport to do T=»$MYVAR»; unset MYVAR; MYVAR=»$T»; unset T ?
@olejorgenb At least in bash, you can say declare +x MYVAR to remove the export but keep the value in the current shell.
Walkthrough of creating and deleting an environment variable in Bash:
Test if the DUALCASE variable exists (empty output):
It does not, so create the variable and export it:
DUALCASE=1 export DUALCASE Check if it is there:
It is there. So get rid of it:
Check if it’s still there (empty output):
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 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 env -i bash env | grep DOGE # Empty output env -i bash command cleared all the environment variables to default on login.
maybe echo $VARIABLE is better than env | grep VARIABLE , it’s lighter as it doesn’t need to print all variables and then send its output to another (grep) process. Plus, env | VARIABLE could catch more than one variable that matches the same pattern. Plus2, echo $VARIABLE makes possible to complete variable’s name by hitting
@RodrigoGurgel, echo $VARIABLE doesn’t tell you whether the VARIABLE is a shell variable (here called «local variable») or an environment variable, which is the whole point of the walkthrough.
Note that env -i bash seems to be creating a subshell (at least on a Mac) which may have unintended consequences.
@RodrigoGurgel using echo won’t show existing variable set to empty string or nul. to your point, though, a proper way to test for variable would be env | grep -e ‘^VARNAME=’ .
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:
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
To unset a variable set with setenv, use
Note: in all the above, I assume that the variable name is ‘x’.
export GNUPLOT_DRIVER_DIR= The variable still exists, but it contains an empty string, as you can see in the output of the env command. It just might be the case that the application that uses the variable does not distinguish between non-existent and empty environment variable.
yes it will contain, this was just to remove value not to remove variable. But yes one can use — unset GNUPLOT_DRIVER_DIR.
This doesn’t work in the case of the PAGER variable. I tried to unset my PAGER setting with export PAGER= , but that just disabled paging entirely—all my man pages just dumped straight to the terminal. unset PAGER did the trick, reverting it to default behaviour.
Perhaps it is time to update your answer? (But without «Edit:», «Update:», or similar — the question/answer should appear as if it was written today.)
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.
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.
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.
You can find more information about environment variables and how to manage them in the following links:
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.