Is subprocess.Popen completely broken?

[Jerry Hill]

On Thu, Mar 27, 2008 at 10:53 AM, Skip Montanaro <skip at pobox.com> wrote:
> I am trying to replace os.system calls with subprocess.Popen.  This simple
>  example fails miserably:
>
>  >>> proc = subprocess.Popen ("ls /tmp")
>  Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
>   File "/home/titan/skipm/local/lib/python2.5/subprocess.py", line 594, in __init__
>     errread, errwrite)
>   File "/home/titan/skipm/local/lib/python2.5/subprocess.py", line 1091, in
>  _execute_child
>     raise child_exception
>  OSError: [Errno 2] No such file or directory
>
>  I also tried explicitly referencing /usr/bin/ls.  Same result.  What gives?

It's looking for an executable named "ls /tmp"  Since it can't find
one, it raises an exception.

If you just want to replace an os.system call, you need to pass
shell=True to Popen, like this:
proc = subprocess.Popen("ls /tmp", shell=True)

That will get the shell to split your string into the program to be
called, and the argument(s) to the program.  Alternatively, you can do
it yourself by passing a sequence to Popen:
proc = subprocess.Popen(["ls", "/tmp"])

Take a look at the documentation for Popen
(http://docs.python.org/lib/node528.html) and the specific examples
for replacing os.system (http://docs.python.org/lib/node536.html)

-- 
Jerry