Python and environment variables

Question

In the following code snippet (meant to work in an init.d environment) I would like to execute test.ClassPath. However, I'm having trouble setting and passing the CLASSPATH environment variable as defined in the user's .bashrc.

Here is the source of my frustration:

When the below script is run in use mode, it prints out the CLASSPATH OK (from $HOME/.bashrc)
when I run it as root, it also displays CLASSPATH fine (I've set up /etc/bash.bashrc with CLASSPATH)
BUT when I do "sudo script.py" (to simulate what happens at init.d startup time), the CLASSPATH is missing !!

The CLASSPATH is quite large, so I'd like to read it from a file .. say $HOME/.classpath

#!/usr/bin/python import subprocess import os.path as osp import os user = "USERNAME" logDir = "/home/USERNAME/temp/" print os.environ["HOME"] if "CLASSPATH" in os.environ: print os.environ["CLASSPATH"] else: print "Missing CLASSPATH" procLog = open(osp.join(logDir, 'test.log'), 'w') cmdStr = 'sudo -u %s -i java test.ClassPath'%(user, ) # run in user proc = subprocess.Popen(cmdStr, shell=True, bufsize=0, stderr=procLog, stdout=procLog) procLog.close()

larsks · Accepted Answer · 2012-06-04 17:16:42Z

sudo will not pass environment variables by default. From the man page:

 By default, the env_reset option is enabled. This causes commands to be executed with a minimal environment containing TERM, PATH, HOME, MAIL, SHELL, LOGNAME, USER and USERNAME in addition to variables from the invoking process permitted by the env_check and env_keep options. This is effectively a whitelist for environment variables.

There are a few ways of addressing this.

You can edit /etc/sudoers to explicitly pass the CLASSPATH variable using the env_keep configuration directive. That might look something like:
```
Defaults env_keep += "CLASSPATH" 
```
You can run your command using the env command, which lets you set the environment explicitly. A typical command line invocation might look like this:
```
sudo env CLASSPATH=/path1:/path2 java test.ClassPath 
```

The obvious advantage to option (2) is that it doesn't require mucking about with the sudoers configuration.

I sudo while calling the script to simulate what happens when init.d calls this script. So, how can I apply this idea at init.d time?
I'm not sure I understand your question. I've suggested how to make your existing script work using the env command. I think this will do what you want. If that doesn't meet your requirements, please update your question (rather than turning this into a giant comment thread) to indicate how the behavior you want differs from the behavior you get using this suggestion.

kjp · Accepted Answer · 2012-06-04 17:40:19Z

You could put source ~/.bashrc before starting your python script to get the environment variables set.

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