On Mon, 7 Sep 2020 10:13:26 +0300 Alexander Krotov <ilab...@gmail.com> wrote:
> > What you could do is to patch a terminal to allow programs to because > > paused via SIGSTOP when invisible and continued via SIGCONT when > > visible. Then your program would only need to write some string to > > the terminal when it starts and when it terminates. Multiplexers > > could however become an issue, but you could patch one as well. > > Sending SIGSTOP stops even the programs that simply do something in the > background, like software update. This will make it impossible to run > something like "apt-get upgrade" in invisible terminal. I meant that this would be something the application would explicitly have to opt in for by writing a special string to the terminal. > > Maybe a better solution is to send XOFF (see > https://en.wikipedia.org/wiki/Software_flow_control), but I am also not > sure how other programs react to it. They will probably block waiting > for the write(2) syscall to return instead of continuing to do work in > the background. > > If they use separate threads/coroutines for the work and for progress > bar update, they will continue to work while progress bar will be > blocked. Once unlocked, they will send the rest of previous progress bar > update, skip all the "frames" that were never displayed and display the > final state. > > Looks like doing an XOFF patch for st and fixing all the programs that > can't handle it properly is the "right thing", but prepare to discover > that badly written programs will stop or even timeout with an error. >
