Subprocess changing directory
I want to execute a script inside a subdirectory/superdirectory (I need to be inside this sub/super-directory first). I can't get
subprocess to enter my subdirectory:
tducin@localhost:~/Projekty/tests/ve$ python Python 2.7.4 (default, Sep 26 2013, 03:20:26) [GCC 4.7.3] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import subprocess >>> import os >>> os.getcwd() '/home/tducin/Projekty/tests/ve' >>> subprocess.call(['cd ..']) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "/usr/lib/python2.7/subprocess.py", line 524, in call return Popen(*popenargs, **kwargs).wait() File "/usr/lib/python2.7/subprocess.py", line 711, in __init__ errread, errwrite) File "/usr/lib/python2.7/subprocess.py", line 1308, in _execute_child raise child_exception OSError: [Errno 2] No such file or directory
Python throws OSError and I don't know why. It doesn't matter whether I try to go into an existing subdir or go one directory up (as above) - I always end up with the same error.
What your code tries to do is call a program named
cd ... What you want is call a command named
cd is a shell internal. So you can only call it as
subprocess.call('cd ..', shell=True) # pointless code! See text below.
But it is pointless to do so. As no process can change another process's working directory (again, at least on a UNIX-like OS, but as well on Windows), this call will have the subshell change its dir and exit immediately.
What you want can be achieved with
os.chdir() or with the
subprocess named parameter
cwd which changes the working directory immediately before executing a subprocess.
For example, to execute
ls in the root directory, you either can do
wd = os.getcwd() os.chdir("/") subprocess.Popen("ls") os.chdir(wd)
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