running shell command in python under git-bash not working well

Question

I am using python3 under git-bash environment, and sometimes it does not run shell command well.

#!/usr/bin/env python3
import subprocess as sp
print("hello")
print(sp.getoutput("ls -l")) # This works.
print(sp.getoutput("date")) # This hangs and cannot terminate with ctrl-c.

This does not happen when running under normal linux/bash environment.

Then I come across this one: Python not working in the command line of git bash.

I can run using "winpty python ...", however it still cannot terminate even with ctrl-c.

I take back, getoutput("date") hangs but check_output works.

• Philippe: Have you tried to run date command in git bash ?
• Charles Duffy: Is the copy of python3 being started a native Windows executable or a cygwin/msys/&c executable? (If it's the latter, the copy of date it starts should be the same as the one bash starts; if it's the former, then not so much). Another important difference is that for a Cygwin python, anywhere it's told to run a shell will start sh; if it's a Windows one, it'll try to start cmd. I would only expect sp.getoutput("ls -l") to ever work with a Windows-built Python; for a Cygwin one or or a more legitimately UNIXy system it needs to be sp.getoutput(["ls", "-l"]) to work at all.
• Charles Duffy: (as a worse-practice alternative, sp.getoutput("ls -l", shell=True) should also work on UNIXy systems, or Python interpreters built for cygwin/msys/etc)
• Charles Duffy: Anyhow -- calling native-Windows date from a more UNIXy Python interpreter, or a more UNIXy date from a native-Windows Python interpreter is liable to cause surprises like those discussed in the other question you linked.

Answer 1

You are needlessly running those commands with a shell.

Prefer this form:

print(sp.check_output(["ls", " -l"]))

print(sp.check_output(["date"]))

• user180574: I notice that it could be a git-bash/python problem, as in stackoverflow.com/questions/32597209/…
• Charles Duffy: There's no implicit shell=True when there's only a single string passed, so the OP is not using a shell -- shell=True needs to be explicit for that. I suspect that the OP is depending on a Windows-ism (the platform takes argument vector as a shell-like string, not a list). Passing a list tells Python to perform escaping that Microsoft's libc will parse back to the desired argument vector if the program being run doesn't override the parsing.