3. subprocess.Popen and subprocess.PIPE classes
The class subprocess.Popen is replacing os.popen. This class uses for process creation and management in the subprocess module. It is handled by the Popen class. Syntax for subprocess.Popen class is explained below:
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)
Execute a child program in a new process. On Unix, the class uses os.execvp() like behavior to execute the child program. On Windows, the class uses the Windows CreateProcess() function.
We can use the same df command 🙂
In : disk = subprocess.Popen(['df', '-h'], stdout=subprocess.PIPE) In : diskusage = disk.communicate() In : print diskusage ('Filesystem Size Used Avail Use% Mounted on\n /dev/vda1 47G 5.5G 39G 13% /\n devtmpfs 3.8G 0 3.8G 0% /dev\n tmpfs 3.8G 0 3.8G 0% /dev/shm\n tmpfs 3.8G 360K 3.8G 1% /run\n tmpfs 3.8G 0 3.8G 0% /sys/fs/cgroup\n tmpfs 773M 0 773M 0% /run/user/0\n', None)
Did you notice the usage of communicate function in above examples? Yeah, it collect piped output from stdout or stderror and pass it to stdin. LOL it’s a good mediator..
Which means it collects the output from “subprocess.Popen” and pass it to next command with .communicate.
You will gen an idea from the above example.
This is a very vast area and I will update it going forth!!