Getting realtime output using subprocess

Question

I am trying to write a wrapper script for a command line program (svnadmin verify) that will display a nice progress indicator for the operation. This requires me to be abl

Answer 1

Depending on the use case, you might also want to disable the buffering in the subprocess itself.

If the subprocess will be a Python process, you could do this before the call:

os.environ["PYTHONUNBUFFERED"] = "1"

Or alternatively pass this in the env argument to Popen.

Otherwise, if you are on Linux/Unix, you can use the stdbuf tool. E.g. like:

cmd = ["stdbuf", "-oL"] + cmd

See also here about stdbuf or other options.

(See also here for the same answer.)