We had 5 smaller builds and a big one. And what I saw was a system going down, freezing.

All resources of the system were used. And 200+ Firefox processes

Needless to say, that without any clue I checked all what might go wrong… to no avail.

Solution: on Unix, the Firefox executable should be binary (firefox-bin), not the script firefox.sh . Make a symbolic link to the binary…

The selenium grid was running on the fresh Linux system with default Firefox.
Not the Firefox binary, but the firefox.sh Obviously, selenium can’t stop the process started through the bash script.
If you watch the selenium log output, you will also see it complaining about the risks of starting Firefox from the script.
That is also possible to run from the shell script, but definitely not the default one.