Os environ python linux

How to set environment variables in Python?

it complains saying that 1 has to be a string. I also want to know how to read the environment variables in Python (in the latter part of the script) once I set it.

19 Answers 19

Environment variables must be strings, so use

import os os.environ["DEBUSSY"] = "1" 

to set the variable DEBUSSY to the string 1 .

To access this variable later, simply use

Child processes automatically inherit the environment of the parent process — no special action on your part is required.

On some platforms, modifying os.environ will not actually modify the system environment either for the current process or child processes. See the docs for more info: docs.python.org/2/library/os.html#os.environ

@Evan There might be some historical variants of Unix that don’t support putenv() , but for those Unixen there is nothing you can do anyway. Even old version of AIX and HPUX I worked with did support it. If anyone is actually able to find a computer not supporting it today, I have severe doubts they will be able to run Python on that computer. 🙂

Caution: to quote from @Evan’s reference above, Such changes to the environment affect subprocesses started with os.system(), popen() or fork() and execv(). In other words, keep in mind that this approach won’t modify the way your program is running, only the way your program’s children run. True, your program can set and read back environment variables, but only from the environment it configures for its children. See also: change current process environment. So far I haven’t found a way for a Python script to modify its parent env.

@SvenMarnach is the statement «child process automatically inherit the environment of the parent process’ true for shell like bash.

You may need to consider some further aspects for code robustness;

when you’re storing an integer-valued variable as an environment variable, try

os.environ['DEBUSSY'] = str(myintvariable) 

then for retrieval, consider that to avoid errors, you should try

os.environ.get('DEBUSSY', 'Not Set') 

possibly substitute ‘-1’ for ‘Not Set’

so, to put that all together

myintvariable = 1 os.environ['DEBUSSY'] = str(myintvariable) strauss = int(os.environ.get('STRAUSS', '-1')) # NB KeyError strauss = os.environ['STRAUSS'] debussy = int(os.environ.get('DEBUSSY', '-1')) print "%s %u, %s %u" % ('Strauss', strauss, 'Debussy', debussy) 

It rarely makes sense to store -1 for a missing integer. A better bet would be myvar = int(os.environ.get(‘MYVAR’)) if os.environ.get(‘MYVAR’, ») != » else None – that way it would be None if no number was provided

If you are dealing with integers, a -1 makes sense. Though I would likely set a variable/constant to the value I would use for not set (e.g., value_not_set = ‘-1’ ). Then, you could use debussy = int(os.environ.get(‘DEBUSSY’, value_not_set))

os.environ behaves like a python dictionary, so all the common dictionary operations can be performed. In addition to the get and set operations mentioned in the other answers, we can also simply check if a key exists. The keys and values should be stored as strings.

For python 3, dictionaries use the in keyword instead of has_key

>>> import os >>> 'HOME' in os.environ # Check an existing env. variable True . 

>>> import os >>> os.environ.has_key('HOME') # Check an existing env. variable True >>> os.environ.has_key('FOO') # Check for a non existing variable False >>> os.environ['FOO'] = '1' # Set a new env. variable (String value) >>> os.environ.has_key('FOO') True >>> os.environ.get('FOO') # Retrieve the value '1' 

There is one important thing to note about using os.environ :

Although child processes inherit the environment from the parent process, I had run into an issue recently and figured out, if you have other scripts updating the environment while your python script is running, calling os.environ again will not reflect the latest values.

This mapping is captured the first time the os module is imported, typically during Python startup as part of processing site.py. Changes to the environment made after this time are not reflected in os.environ, except for changes made by modifying os.environ directly.

os.environ.data which stores all the environment variables, is a dict object, which contains all the environment values:

>>> type(os.environ.data) # changed to _data since v3.2 (refer comment below)

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Python OS Environ

The recipient’s environmental variables are represented via the programming languages navigation object, the “os.environ”. It gives back a dictionary with the participant’s environmental variables entries as keys. It operates similarly to a Python dictionary to allow the typical standard dictionary activities, like how to get and modify it, to be accomplished. We could also alter the “os.environ” but doing so merely has an impact on how it is currently designated and won’t alter the result permanently. The bundle of authentication mechanisms for the active user condition is considered as the environment variable. The operating system and the existing viewer parameters usually determine them.

A sequence of characters that are kept in the rendition specification of a process are referred to as environment variables where the environment variables are available to our code by the Lambda runtime. The extra context variables are supplied with details about the procedure and activation request using the “env” keyword to display together all the environment variables or “printenv” to retrieve every variable while including the operands and the usage of the “set” command.

Example 1: Utilizing the Python “Os.Environ” Command to Access the Environment Variables

This module is an inactive object. As a result, no argument is needed. A lexicon which contains the user’s explanatory factors is returned. The environment variables exist in ram rather than on the hard drive. The enviro inputs are typically saved in records so that people don’t have to manually outsource them repeatedly.

Let us create the code for having an access to the environment variable. With due, we need interaction with the system as well. So, we import the library of “os” first in our code. Then, an additional library of “pprint” is also imported since it must be required for the environmental variable. Now, we create a user-defined function of the name “Environ_Variable” and apply it to the command that we are discussing in this article which is “os.environ”.

After providing the “os.environ” command, we use the “print()” function and provide the print statement of “Environment Variable For User:” Lastly, we use the “pprint.pprint()” function with the connectivity to the library of “pprint” and store our function of “Environ_Variable” where the “os.environ” command is stored. Then, we apply the “width” value to “1”.

Let us implement the respective code that we provided in the previous image. Then, we obtain this output for the “os.environ” command. After the implementation, our output displays the environment of our operating system. The first line displays the “Environment Variable For User:” print statement. After that, the whole environmental series is displayed. It shows the pathway of the user profile along with the program file and the system name of the processors.

The processor level for the operating system in the environment is shown as well. Our system processing level is determined as “6” which we can see in the following output snapshot:

The third output that we can see describes the environmental scale factors file’s location with the session names for the console since the running tool is “spyder”. It describes the whole environment of the tool along with the user path directories. As we can see, some “False” verbose can also be seen in the output screen due to the absence of this property of interaction with the system environment.

Example 2: Utilizing the “Os.Environ” to Handle the Access Errors While Attempting to Retrieve an Environment Variable that Doesn’t Exist but Allows the Access to the Environment Variables

Now, we look at the handling of the errors that occur during the access of a variable environment that is not present and not reachable since it does not exist.

Let us look at the second example of “os.environ” where we take the library of “os” first. Then, we use the “print()” function where we take the statement of “Users” and apply the “os.environ.get()” function on the “Users”. Then, we provide the print statement of “It does not exist in the environment:”.

Let us have a look at the code implementation of “os.environ”. After the implementation of the code, we get the following output which describes that it is absent in the system environment with the “User: It does not exist in the environment:” statement.

Example 3: Utilizing the “Os.Environ” Module for the New Environment Variables Getting Loaded

In this example, we use a similar library that was used in the previous two examples which is “os”. Then, we use our command of “os.environ”, grant it the environmental value of “Warplex”, and assign the value of “www.Warplex.org”. Now, we add a “print()” function where we use “Warplex:”. Then, we utilize the functional command of “os.environ” and call the assigned environment variable to describe its value.

This is the particular output that comes after the implementation of our code. We get the “Warplex” along with its environment that is somehow related to a specific website which is “www.Warplex.org” in our output screen.

Example 4: Utilizing the “Os.Environ” Command for Environment Variable Modification

This is the fourth example. We discuss about the topic of “os.environ” in overcoming the process of any kind of modification in the specific environment variable. For modification purposes, we need to have at least two functions that could hold the “os.environ” command to make and do changes in the environment.

Let’s start doing our coding. We start our code with the “os” library addition by the import in our Python code. Now, we create our new function name, “user”. In this function, we apply the “os.environ” command and assign it a new variable function value of “Users” as far as modification purposes. Then, we use the “print()” function. Here, we use “Users” as the print statement and call the “user” and grant its value within the print function to display it in the output. Here, we create a new function again with the name “python_user”, implement the “os.environ” command on this function, and modify its value.

We granted its environment variable to a new “PYTHON_Users” value which changes the environment of this function. Then, we use the “print()” function and use the “PYTHON_Users” as the print statement. We call the “python_user” function within the print function for its environmental value. This step modifies the environment of the second function variable with the new variable for the environment.

Let us implement our code for the fourth example of “os.environ”. After the implementation, the output displays two lines where the first line shows the “User” and prints its environment which is /User/AqsaY”. The second line of the output describes the environment of the second function with the name on the left side, “PYTHON_Users:”, and with the environmental variable address value which is “/opt/jdk-11.1.1” which can be clearly seen.

Conclusion

In this article, we discussed our Python’s important command of “os.environ” in a deep manner with the help of four different complex examples. The first example elaborates on the phenomenon of accessing the environmental variable. The second example defines the error handling by the “os.environ” command when the variable doesn’t even exist in the operating system. The third example covers the topic of adding a new variable to our environment. And the fourth or last example covers the phenomenon of modifying the variable of the environment in the system.

About the author

Aqsa Yasin

I am a self-motivated information technology professional with a passion for writing. I am a technical writer and love to write for all Linux flavors and Windows.

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