Comment 47 for bug 1007089

Ohh, one added point is that you are only looking for overlayfs mounts:
lnk=$(readlink /proc/$(pgrep firefox)/exe); for ech in $(cut -f2,3 -d\ /proc/mounts | grep ' overlayfs$' | cut -f1 -d\ ); do [ -f "$ech$lnk" ] && echo "$ech$lnk"; done
/usr/lib/firefox/firefox