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If standard output is a terminal, the command's standard output is appended to the file 'nohup. out'; if that cannot be written to, it is appended to the file '$HOME/nohup. out'; and if that cannot be written to, the command is not run. But if I already have one command using nohup with output going to /nohup.
Since there isn't a terminal to associate with it, nohup logs everything to an output file, nohup. out . By default, that file is located in whichever directory you started the command in. nohup.
The short answer is to use nohup python -u args... to force python to print and flush buffer for each print() call. I believe this is due to Python's default behaviour to write to buffer first, but nohup doesn't trigger the buffer to be cleared.
nohup is a POSIX command which means "no hang up". Its purpose is to execute a command such that it ignores the HUP (hangup) signal and therefore does not stop when the user logs out.
You can run Python with the -u flag to avoid output buffering:
nohup python -u ./cmd.py > cmd.log &
It looks like you need to flush stdout periodically (e.g. sys.stdout.flush()). In my testing Python doesn't automatically do this even with print until the program exits.
Using -u with nohup worked for me. Using -u will force the stdout, stderr streams to be unbuffered. It will not affect stdin. Everything will be saved in "nohup.out " file. Like this-
nohup python -u your_code.py &
You can also save it into your directory. This way-
nohup python -u your_code.py > your_directory/nohup.out &
Also, you can use PYTHONUNBUFFERED. If you set it to a non-empty string it will work same as the -u option. For using this run below commands before running python code.
export PYTHONUNBUFFERED=1
or
export PYTHONUNBUFFERED=TRUE
P.S.- I will suggest using tools like cron-job to run things in the background and scheduled execution.
export PYTHONUNBUFFERED=1
nohup ./cmd.py > cmd.log &
or
nohup python -u ./cmd.py > cmd.log &
https://docs.python.org/2/using/cmdline.html#cmdoption-u
Python 3.3 and above has a flush argument to print and this is the only method that worked for me.
print("number to train = " + str(num_train), flush=True)
print("Using {} evaluation batches".format(num_evals), flush=True)
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