_bg doesn't work if not being assigned

[dmd]

sh.sleep(5, _bg=True)   # blocks for 5 seconds

x = sh.sleep(5, _bg=True)   # returns immediately

[amoffat]

Are you running this in a python shell by chance? The python shell will try to evaluate the return value of a function, if you're not assigning it to a variable, thereby causing sleep to block.

[dmd]

Yes, I am. Ok, that makes sense, thanks. Is there any way to get a background process started by sh to persist after the python program has ended? I get "Exception in thread Thread-1 (most likely raised during interpreter shutdown)".

[amoffat]

So I looked at the code. It should be possible, in theory, to do:

import sh
sh.nohup.sleep(60, _bg=True)

And a sleep process should exist in the background. The problem is this line, which adds the spawned process to a list of processes to be killed on script exit, if persist is False. persist will always be False though, because it looks like a feature that didn't get fully built.

If you want to add this for yourself and everyone else, I would remove the persist keyword argument on OProc, and in its place, use self.call_args["persist"], then add the persist special argument here. This would allow you to do:

import sh
sh.nohup.sleep(60, _bg=True, _persist=True)

[dmd]

I've decided not to use sh after all but rather to rework my code so I don't have to shell out in the first place, so I'm not going to bother. Sorry...

[amoffat]

spawned processes now persist after exit by default and ignore SIGHUP

[JonathanRRogers]

Unfortunately, this change seems to make foreground subprocesses persist after the Python sh process as well as background, which is very surprising compared with /bin/sh.