Python和环境变量

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()

Answer 1

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.

1. 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" 

2. 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.

Answer 2

您可以在启动python脚本之前放置source ~/.bashrc ，以设置环境变量。