Since os.popen is being replaced by subprocess.popen, I was wondering how would I convert
os.popen('swfdump /tmp/filename.swf/ -d')
to subprocess.popen()
I tried:
subprocess.Popen("swfdump /tmp/filename.swf -d")
subprocess.Popen("swfdump %s -d" % (filename)) # NOTE: filename is a variable
# containing /tmp/filename.swf
But I guess I'm not properly writing this out. Any help would be appreciated. Thanks
subprocess.Popen takes a list of arguments:
from subprocess import Popen, PIPE
process = Popen(['swfdump', '/tmp/filename.swf', '-d'], stdout=PIPE, stderr=PIPE)
stdout, stderr = process.communicate()
There's even a section of the documentation devoted to helping users migrate from os.popen to subprocess.
shell=True is not recommended.
filename.swf; rm -rf / for the value of filename. However, this is only a problem, when the contents of your argument to Popen is insecure.shell=True except when using untrusted input. Simply stating that shell=True is not recommended is misleading.
shell=True, but any random user stumbling across this question might not be. That's why I think it's important to highlight that shell=True in fact isn't recommended, unless you know exactly what you're doing.shutil.rmtree for example. But that has nothing to do with whether they are included in the stdlib or not. I believe the UNIX philosophy of "Unix was not designed to stop its users from doing stupid things, as that would also stop them from doing clever things." also applies in large parts to Python.In the recent Python version, subprocess has a big change. It offers a brand-new class Popen to handle os.popen1|2|3|4.
The new subprocess.Popen()
import subprocess
subprocess.Popen('ls -la', shell=True)
Its arguments:
subprocess.Popen(args,
bufsize=0,
executable=None,
stdin=None, stdout=None, stderr=None,
preexec_fn=None, close_fds=False,
shell=False,
cwd=None, env=None,
universal_newlines=False,
startupinfo=None,
creationflags=0)
Simply put, the new Popen includes all the features which were split into 4 separate old popen.
The old popen:
Method Arguments
popen stdout
popen2 stdin, stdout
popen3 stdin, stdout, stderr
popen4 stdin, stdout and stderr
You could get more information in Stack Abuse - Robert Robinson. Thank him for his devotion.
It may not be obvious how to break a shell command into a sequence of arguments, especially in complex cases. shlex.split() can do the correct tokenization for args (I'm using Blender's example of the call):
import shlex
from subprocess import Popen, PIPE
command = shlex.split('swfdump /tmp/filename.swf/ -d')
process = Popen(command, stdout=PIPE, stderr=PIPE)
stdout, stderr = process.communicate()
