How to access 'missing' Environmental variables?

Question

I am adding an environmental variable in bashrc, but am unable to see the variables using os.environ.get in a Python file.

I am using Raspbian on a Raspberry Pi 4.

I am setting an environmental variable in “bashrc” as follows:

export DB_USER='[email protected]'

When calling the following on Terminal:

$ env

…I find DB_USER in a the list of 24 items.

However, when I use the following in a Python file (this file is called by a bash script):

import os
...
try:
    with open("tempFile.txt", "a") as f:
        f.write(str(os.environ))
        f.close()
except FileNotFoundError:
    print("FileNotFoundError")
except IOError:
    print("IOError")

then ‘DB_USER’ is not in the list of 11 entries in "tempFile.txt".

How can I access the list of 24 items so that I can use ‘DB_USER’ entry?

Thanks

How are you running the Bash script that calls the Python script? From the command line? Or some other method? — MattDMo
– MattDMo, Commented Nov 6, 2022 at 16:26
bashrc is available only in a bash environment. See here. Therefore the question of @MattDMo. Also, check whether you start the script as normal user or via sudo. — cwellm
– cwellm, Commented Nov 6, 2022 at 18:19
@MattDMo - The Python script it being called by a Bash script. In turn, the Bash script is being called by a service. — Ron
– Ron, Commented Nov 6, 2022 at 18:22
Check out serverfault.com/questions/413397/… for some possible solutions. My Pi is currently AWOL, so I can't verify if Raspbian uses systemd, but the google machine says it does, so the first solution in the first answer should work. — MattDMo
– MattDMo, Commented Nov 6, 2022 at 18:29
The service isn't inheriting its environment from your shell, which means Python isn't either. — chepner
– chepner, Commented Nov 6, 2022 at 18:35

JL Peyret · Accepted Answer · 2022-11-06 21:22:46Z

1

Since this is a service (so, not your user, as per Chepner's comment) calling something this looks like you want to make the environment variable available system-wide.

/etc/environment may fit your needs. You would just add

[email protected]

to it. (no, don't use export)

See also https://superuser.com/questions/664169/what-is-the-difference-between-etc-environment-and-etc-profile and https://raspberrypi.stackexchange.com/questions/37771/setting-system-wide-path-not-working-in-etc-environment (which talks about using /etc/profile.d instead, but similar concept - that's probably the approach I'd take, after testing a basic /etc/environment based fix)

edited Nov 6, 2022 at 21:22

answered Nov 6, 2022 at 20:52

JL Peyret

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TheAnalogyGuy · Accepted Answer · 2022-11-06 21:44:57Z

0

Try something like this:

import os, subprocess

# try to simulate being the user so you can import/capture the env as that user
cmd = 'env -i sh -c ". /home/user/.bashrc && env"'

try:
    with open("tempFile.txt", "a") as f:
        for line in subprocess.getoutput(cmd).split("\n"):
        f.write(str(line))
        f.close()
except FileNotFoundError:
    print("FileNotFoundError")
except IOError:
    print("IOError")

answered Nov 6, 2022 at 21:44

TheAnalogyGuy

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Ron · Accepted Answer · 2022-11-12 13:52:27Z

I’ve managed to find a solution thanks to the suggestions given in this post.

I’m currently using /etc/environment in a script as follows :

  # get environmental variables
  source /etc/environment
  
  afile='<file path and name>‘

  date >> $afile
  
  echo >> $afile
  echo Straight from set >> $afile
  echo $DB_USER_environment >> $afile
  echo >> $afile
  
  echo Via a variable in the script >> $afile
  db_user02=$DB_USER_environment
  echo $db_user02 >> $afile
  
  echo >> $afile

This adds the following to afile

Sat 12 Nov 11:56:11 GMT 2022

Straight from set
[email protected]

Via a variable in the script
[email protected]

I intend to look at the etc/profile.d (@JL Peyret), Python (@TheAnalogyGuy) and systemd (@MattDMo) suggestions.

Thanks for all the replies

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