Nohup: ignoring input – what does it mean

GNU coreutils nohup man page indicates that you can use normal redirection:

If standard input is a terminal, redirect it from /dev/null. If standard output is a terminal, append output to 'nohup.out' if possible, '$HOME/nohup.out' otherwise. If standard error is a terminal, redirect it to standard output. To save output to FILE, use 'nohup COMMAND > FILE'.

Edit: I didn't read your link at first; you may have a different version of nohup, although this section suggests that you can still use normal redirection:

 nohup.out          The output file of the nohup execution if
                    standard  output is a terminal and if the
                    current directory is writable.

You can redirect standard output and standard error to different files:

nohup myprogram > myprogram.out 2> myprogram.err

or to the same file:

nohup myprogram > myprogram.out 2>&1

nohup only redirects the command's output if it's going to a terminal. If the output is already going to another type of file (e.g. regular file or a pipe), nohup assumes that this is desired and does not redirect to nohup.out.

By default, docker run runs the command via a socket (connecting the host with the virtual environment — that's how they communicate). A socket isn't a terminal so nohup doesn't perform any redirection.

If you run docker run -t then Docker will emulate a terminal in the container and so nohup will redirect to nohup.out. If you don't pass a command name then docker acts as if you'd used docker run -t bash.

The best solution is to explicitly redirect the output of the command to your choice of log file. Don't forget to redirect stderr as well. That way you'll know where they're going.

nohup awk 'BEGIN { while (c++<50) print "y" }' >myscript.log 2>&1 &