Question

Caveat: new to Python.

Wanting to hear from professionals who actually use it:

What are the main differences between subprocess.Popen() and subprocess.call() and when is it best to use each one?

Unless you want to read why I was thinking about this question or what to center your answer around, you may stop reading now.

I was inspired to ask this question because I am working through an issue in a script where I started using subprocess.Popen(), eventually called a system pause, and then wanted to delete the .exe that created the system pause, but I noticed with Popen(), the commands all seemed to run together (the delete on the .exe gets executed before the exe is closed..), though I tried adding communicate().

Here is fake code for what I’m describing above:

subprocess.Popen(r'type pause.exe > c:\worker.exe', shell=True).communicate()
subprocess.Popen(r'c:\worker.exe', shell=True).communicate()
subprocess.Popen(r'del c:\worker.exe', shell=True).communicate()

Answer 1

subprocess.call(*popenargs, **kwargs)
Run command with arguments. Wait for
command to complete, then return the
returncode attribute.

If you create a Popen object, you must call the sp.wait() yourself.

If you use call, that’s done for you.