fg a bg process because you forgot to redirect output to /dev/null

Question

I did Ctrl+Z bg with the intention of disowning next, but I forgot to redirect, now I cant get to my terminal because the scrolling of the output (tarballed a huge directory with verbose set).

How do I get a prompt when STDOUT from tar is filling the screen and I already sent it to the background?

I am using Bash 4.

Answer 1

You actually have a prompt already, you just can't see it because it's scrolled off screen.

The simplest thing to type is probably Ctrl-C (to kill any partial line you've typed at the prompt), fg, enter, Ctrl-Z which will bring it back to the foreground then suspend it again. Simple is nice in this case as you're doing it blindly.

It may take a few seconds to work, as your terminal is struggling to keep up with the output.

You can see clearly what this does by using a command that spews to the terminal slowly (note that my PS1 includes $? when non-zero):

anthony@Zia:~$ perl -E 'say "ha" while sleep(1)'
ha
ha
^Z
[1]+  Stopped                 perl -E 'say "ha" while sleep(1)'
anthony@Zia:~ [$?=148]$ bg %1
[1]+ perl -E 'say "ha" while sleep(1)' &
ha
anthony@Zia:~$ ha
ha
ha
ha
ha
^C
anthony@Zia:~ [$?=130]$ ha
fha
g
perl -E 'say "ha" while sleep(1)'
ha
^Z
[1]+  Stopped                 perl -E 'say "ha" while sleep(1)'
anthony@Zia:~ [$?=148]$ 

At this point, you have it stopped again, and can do whatever you'd like with it.