Python sys.executable 为空

Question

我正在测试用 os.execve 和虚拟环境做一些恶作剧。如果我将当前 python 进程替换为另一个 python 子进程，我将运行解决 sys.executable 为空的问题。

下面的示例显示了正在发生的事情（运行 this inside a python shell）：

import os, sys
print(sys.executable) # works this time
os.execve("/usr/bin/python", [], {}) # drops me into a new python shell
import sys # yes, again
print(sys.executable) # is empty

我运行在 python shell:

中执行上述命令的完整输出

 lptp [ tmp ]: python
Python 2.7.10 (default, Oct 14 2015, 16:09:02) 
[GCC 5.2.1 20151010] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import os, sys
>>> print(sys.executable) # works this time
/usr/bin/python
>>> os.execve("/usr/bin/python", [], {}) # drops me into a new python shell
Python 2.7.10 (default, Oct 14 2015, 16:09:02) 
[GCC 5.2.1 20151010] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys # yes, again
>>> print(sys.executable) # is empty

>>>

sys.executable 为空导致我出现问题，最值得注意的是 platform.libc_ver() 失败，因为 sys.executable 为空：

>>> import platform
>>> platform.libc_ver()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/platform.py", line 163, in libc_ver
    f = open(executable,'rb')
IOError: [Errno 21] Is a directory: '/tmp'

请注意，上面的示例是运行在调用 os.execve(...)

之后

Answer 1

Python 依赖于 argv[0] 和几个环境变量来确定 sys.executable。当你传递一个空的 argv 和环境时，Python 不知道如何确定它的路径。至少，您应该提供 argv[0]:

os.execve('/usr/bin/python', ['/usr/bin/python'], {})

Python sys.executable 为空

Python sys.executable is empty

python

execve