Linux – put a job in the bg and run it

Answer found.

For BASH, this depends on the huponexit shell option, which can be viewed and/or set using the built-in shopt command.

Looks like this options is off by default, at least on RedHat-based systems.

More info on the BASH man page:

The shell exits by default upon receipt of a SIGHUP. Before exiting, an interactive shell resends the SIGHUP to all jobs, running or stopped. Stopped jobs are sent SIGCONT to ensure that they receive the SIGHUP. To prevent the shell from sending the signal to a particular job, it should be removed from the jobs table with the disown builtin (see SHELL BUILTIN COMMANDS below) or marked to not receive SIGHUP using disown -h.

If the huponexit shell option has been set with shopt, bash sends a SIGHUP to all jobs when an interactive login shell exits.

When you exit an interactive bash login shell, it sends a SIGHUP to all children unless the shell option huponexit is set to off.

When most userland processes receive a SIGHUP, they will exit.

When you disown -h, you are marking the process to prevent bash from sending a SIGHUP on exit regardless of the shell options. You could have also prefixed the command with nohup to reproduce this same behavior.

As far as STAT D:

An uninterruptible sleep state is a sleep state that cannot handle a signal (such as waiting for disk or network IO (input/output)).