How to unset Linux environment variables in Python

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In this article, we'll learn different ways to unset Linux environment variables in Python. The most useful method is to use the unset command.

However, we can unset Linux environment variables in Python using several other methods. Read the article to explore more information.

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Unset Linux environment variables in Python

Python is available for different operating systems (OS). Linux is one of the operating systems where Python can be used.

Although we can use both Linux and Python, there are some differences between the two. One of the differences we need to consider is how environment variables are interpreted.

If we want to unset an environment variable we previously set, we can use the method in Python os.unsetenv().

This function will remove the environment variable from the current process and accepts the name of the environment variable as an argument. Additionally, the function will remove environment variables from the current process.

Therefore, it is important to remember that unsetting a shell environment variable using Python does not remove the value from the shell. If an environment variable is set in the shell, Python's subprocesses can still access it, even if they are started after the Python process.

If you want to clear environment variables from the shell, you should use the unset command.

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How to unset Linux environment variables in Python

Python provides many options for removing and unsetting values ​​from environment variables on Linux in Python.

1. Using the unset command is the most typical and commonly used method. With this command, the environment variables are removed from the now active shell.
2. Python's export command provides an additional way to clear previously set Linux environment variables. This command will remove the environment variable from the active shell and any child processes.
3. Finally, another option is to utilize the os.environ.pop technique. After executing this method, the environment variable will be removed from the os.environ dictionary.

The strategy we choose is based on our requirements.

1. If we want to clear environment variables from the shell we are using right now, we will use the unset command.
2. If we want to clear environment variables from the currently active shell and any child processes, we will use the export command.
3. If we just want to remove environment variables from the os.environ dictionary, we can use the os.environ.pop function.

Use os.environ to remove or unset one of the environment variables

When using Python on Linux, we may need to remove or unset one of these environment variables.

For example, if we configured the PYTHONPATH environment variable to point to a certain location and we now wish to remove that setting, we can use the code provided in the example below.

#import os library
import os
# Unset the path with the command
os.environ.pop('PYTHONPATH', None)

This action will remove the PYTHONPATH environment variable from the os.environ dictionary. If no environment variable is set in this case, nothing will happen.

Use del os.environ to unset one of the environment variables

We can also use the code provided below to clear the option of the environment variable.

#import operating system
import os
# use this command to unset
del os.environ['PYTHONPATH']

output:

KeyError                                  Traceback (most recent call last)
KeyError: 'PYTHONPATH'

This action will remove the PYTHONPATH environment variable from the os.environ dictionary. This will result in a KeyError if the environment variable is not set.

Remove and replace variables with os.environ.unsetenv and os.environ

If we wanted to clear the value assigned to the variable USER and replace it with the word nobody, you would do something like this:

import os
os.environ.unsetenv("USER")
os.environ["USER"] = "nobody"

The above code clarifies the value assigned to the variable USER and replaces it with the word nobody.

Use os.environ.unsetenv to unset

The second parameter can be omitted if we just want to clear the value of the variable. For example, if you do the following, the USER variable will not be set.

import os
os.environ.unsetenv("USER")

The above code clears the value of the variable. The USER variable is not set.

Use os.environ.get() to check if a variable is set before unsetting it

Checking whether a variable is set before unsetting it can also os.environ.get()be done with the help of the function. You can use this to your advantage if you just want to unset a variable that is currently set.

For example, if the USER variable has been defined as nobody, the following code will only delete its value.

Sample code:

import os
if os.environ.get("USER") == "nobody":
  os.environ.unsetenv("USER")

As we know, clearing a variable's value doesn't always mean removing it from the environment. It just sets the value to an empty string.

If you want to completely remove a variable from the environment, you can use os.environ.pop()the function. This function will remove the variable from the environment, returning its value before being removed.

Sample code:

import os
prev_value = os.environ.pop("USER", None)
print(prev_value)  # prints "nobody"

output:

nobody

This code will delete the USER variable from the environment and return the value before deletion.

We hope you found this Python article helpful in understanding how to unset Linux environment variables in Python.