Need to parallel run a video on multiple hosts BASH-CodePudding

So I have a for loop where

  for HOST in $HOST_LOOP
   do
     ssh $HOST ... play video ... &
  done
  wait

I wanted to play the video on those hosts at the same time, that's what the & is for and the wait is for the script to keep running. But when I try to exit the bashscript, the processes still run on the background and the video keeps playing. I want to kill the processes, and I know that an individual host kills the video by ssh $Host pkill ffplay

So how can I kill these processes? The thing really throwing me off is this wait because it has essentially nothing to wait for, and it's becoming an infinite loop...

CodePudding user response：

how can I kill these processes?

for HOST in $HOST_LOOP; do
   ssh $HOST 'kill ...the_process_that_plays_the_video'
done

The quick and dirty solution is to run ssh -tt, that will forward signals to process runnin gon the other side.

CodePudding user response：

GNU Parallel had exactly the same problem.

It was solved by making a wrapper, that checked if the ssh connection was still there and if not: killed the local job. https://www.gnu.org/software/parallel/parallel_design.html#the-remote-system-wrapper

So maybe you can do:

# GNU Parallel wants hosts as: "host,host,host" not as "host host host"
hosts=$(echo "$HOST_LOOP" | perl -pe 's/ /,/g')
parallel -j0 -S"$hosts" --nonall play video

If this does not kill the job, try changing --termseq.