While I was running
apt upgrade I accidentally sent a Ctrl-S to that terminal window.
Now I know of
XON, Ctrl-Q, and something new about teletype.
When I sent a Ctrl-Q to the "paused" terminal,
apt continued with its work.
From reading about
XOFF, it is unclear to me what happened in
apt, or what happens generally in any command which receives an
htop stops updating the display, which is something good to know, but is
htop still running?
apt still running? Or was
htop effectively paused, frozen?
Apparently the processes can still receive input, while
XOFF'd, so they are still executing.
What is happening? For example, the program counter, apparently it doesn't simply stop incrementing the program counter, freezing the program.
Does it depend on how the command is programmed to handle XOFF? Is there a general behavior that can be expected with the basic Linux commands?