Windows10下运行高校Python脚本创建临时目录失败，报KeyError

Hey there, let's break down what's going wrong here and fix it step by step.

First, let's zero in on the root of your error:

Traceback (most recent call last):
File "Calign.py", line 116, in
tmpbase = '/tmp/' + os.environ['USER'] + '_' + str(os.getpid())
File "C:\Python27\lib\os.py", line 425, in getitem
return self.data[key.upper()]
KeyError...

Why this happens #

The script was clearly written with Linux/Unix systems in mind, not Windows—here are the two main mismatches:

1. Environment variable difference: Linux uses USER to store the current username, but Windows uses USERNAME instead. When the script tries to fetch os.environ['USER'], that key doesn't exist on your system, triggering the KeyError.
2. Temporary directory path mismatch: Windows doesn't have a /tmp/ directory by default. That path is standard on Linux, but Windows uses a system-specific path like C:\Users\<YourName>\AppData\Local\Temp for temporary files.

Solutions to fix this #

Option 1: Cross-platform fix (best approach)

Update the script to work on both Windows and Linux by using Python's built-in tempfile module, which handles system-specific temp directories automatically, plus fallback logic for the username.

First, add this import at the top of the script (if it's not already there):

import tempfile

Then replace line 116 with this code (tailored for Python 2.7):

# Grab username with cross-platform fallback
username = os.environ.get('USER', os.environ.get('USERNAME', 'temp_user'))
# Create a unique temp directory using system's default temp location
tmpdir = tempfile.mkdtemp(prefix="{0}_".format(username))

This code:

• Pulls the correct username variable for your OS, with a default if neither exists.
• Creates a unique temporary directory in Windows' default temp folder, so you don't have to hardcode /tmp/.

Option 2: Windows-only quick fix

If you only need this script to run on Windows, you can modify the original line directly:

tmpbase = os.path.join(os.environ['TEMP'], os.environ['USERNAME'] + '_' + str(os.getpid()))

• os.environ['TEMP'] fetches Windows' default temp directory path automatically.
• os.environ['USERNAME'] uses your Windows username instead of the Linux-style USER.

Testing the fix #

After making either change, run the script again—you shouldn't hit the KeyError anymore, and the script should successfully create its temporary directory without issues.

内容的提问来源于stack exchange，提问作者George Corley