python - os.getenv 和 os.environ 看不到我的 bash shell 的环境变量
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python - os.getenv and os.environ don't see environment variables of my bash shell
提问by xealits
I am on ubuntu 13.04, bash, python2.7.4
我在 ubuntu 13.04，bash，python2.7.4
The interpreter doesn't see variables I set.
解释器看不到我设置的变量。
Here is an example:
下面是一个例子：
$ echo $A
5
$ python -c 'import os; print os.getenv( "A" )'
None
$ python -c 'import os; print os.environ[ "A" ]'
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/usr/lib/python2.7/UserDict.py", line 23, in __getitem__
raise KeyError(key)
KeyError: 'A'
But everything works fine with the PATHvariable:
但是对于PATH变量一切正常：
$ echo $PATH
/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
$ python -c 'import os; print os.getenv("PATH")'
/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
And it notices changes in PATH:
它注意到以下方面的变化PATH：
$ PATH="/home/alex/tests/:$PATH"
$ echo $PATH
/home/alex/tests/:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
$ python -c 'import os; print os.getenv("PATH")'
/home/alex/tests/:/usr/lib/lightdm/lightdm:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
What could be wrong?
可能有什么问题？
PS the problem comes when using $PYTHONPATH:
PS使用时出现问题$PYTHONPATH：
$ python -c 'import os; print os.getenv("PYTHONPATH")'
None
采纳答案by xealits
Aha! the solution is simple!
啊哈！解决办法很简单！
I was setting variables with plain $ A=5command; when you use $ export B="kkk"everything is fine.
我用普通$ A=5命令设置变量；当你使用$ export B="kkk"一切都很好。
That is becauseexportmakes the variable available to sub-processes:
- it creates a variable in the shell
- and exportsit into the
environmentof the shell - the list
environmentis passed to sub-processes of the shell.
- 它在shell中创建一个变量
- 并将其导出到
environment外壳的 - 该列表
environment被传递给 shell 的子进程。
Plain $ A="kkk"just creates variables in the shell and doesn't do anything with the environment.
Plain$ A="kkk"只是在 shell 中创建变量，对environment.
The interpreter called from the shell obtains it's environmentfrom the parent -- the shell. So really the variable should be exported into the environmentbefore.
从 shell 调用的解释器从environment父级——shell 获取它。所以真的应该将变量导出到environment之前。
回答by Yann Vernier
Those variables (parameters in bash terminology) are not environmentvariables. You want to export them into the environment, using exportor declare -x. See the bash documentation on environment.
这些变量（bash 术语中的参数）不是环境变量。您想使用export或将它们导出到环境中declare -x。请参阅有关 environment的bash 文档。
