So, I have a shell script that launches mpv in the background to connect to my remote MPD server:

$ cat $(which stream-mpd)
#!/bin/bash
pkill -f "mpv http://mysever"
mpv http://myserver &

If I launch this from the command line, everything works as it should, mpv runs in the background even if I close the terminal, etc. However, if I try to hook it up to my mpd module in polybar (so that I can actually listen to the stream that I am remote-controlling with the module) like so:

format-online = %{A3:stream-mpd:}<label-song> %{A}  <icon-prev> <icon-seekb> <icon-stop> <toggle> <icon-seekf> <icon-next>  <icon-repeat> <icon-random>

then something strange happens: the mpv process is killed as soon as stream-mpd exits. I can confirm this by adding a sleep 10 as the last line of my script: polybar will freeze up for 10 seconds since the script is running, but then once the 10 seconds are up, mpv is killed too! I can't explain why that happens - is polybar going out of its way to clean up the children of all the processes it spawns? Is there a way to accomplish what I'm after (which is to start a background task as an input trigger)?