Found a way in which Lightburn fails non-obviously; check /run/lock!

Community Laser Talk
1

I really like the software. I bought a license for my new 10W Comgrow. However, I spent easily a good day or two trying to dork around with why I couldn’t connect to the laser with linux before I finally got it working and bought it. I had tried forever with an old ubuntu 20.04 install, no avail, couldn’t get windows installed on this laptop (and I didn’t feel like paying for a license key), and so tried Fedora 39. After a while I finally got LightBurn to talk to the laser cutter. I knew the laser cutter worked fine, I had connected earlier with my main win10 laptop (I didn’t want to use that laptop though, I wanted to dedicate this laptop to the laser cutter since it’s been just sitting around to no good use).

Anyway, under Fedora 39, I could get lightburn to talk using sudo Lightburn acting as superuser, but it wasn’t my preferred way. Running as regular user, I couldn’t get it to do squat. It would just fail with “Failed to open port - already in use?” with no explanation. I had at this point gone through all the steps to add my user to dialout, tty, ensure brltty wasn’t taking up the port, added a udev rule to make it mode 0666, etc etc. After running an lsof (nothing showed as using the port), strace, inotifywatch etc, it turns out there was an errant lock file in /run/lock on the port. It seems lightburn somehow was seeing the lock file, and saying “oops, its in use” but not really saying why it thought that.

A suggestion for a next revision to tell if there’s a lock file that shouldn’t be there. I have no clue how the lock file got there, but it did.

Anyway, looking forward to making cool stuff with this thing. LightBurn does exactly what I wanted it to.

2

In case you didn’t know or it’s changed, you can install win10 and run it without activation.

3

No, more in that windows 10 wouldn’t even install on the laptop properly, kept on failing and losing the boot drive. And yes, I could in theory run it without activation, but my OCD wouldn’t really take that well (that’s a me issue, not a Lightburn/Windows issue). Prefer fewer computers running windows in my house either way.

4

Perfectly legal. You just can’t customize which I don’t really care about.

5

So what did you do to resolve the issue? I’m guessing this was not actually spurious and was a legitimate lock.

6

It wasn’t a legitimate lock. I just deleted it and haven’t had any issues since. I don’t know what created it, I forgot to look at what user owned the lock, I just saw it and said “Huh, lets try deleting it as root” and it worked every time after that.

7

How are you determining that it wasn’t a legitimate lock? By legitimate I mean that some application placed it there and had not yet released it.

Your fix addressed the issue but it’s likely that there was an underlying cause not directly addressed.

8

In that it hasn’t shown back up again since (which is basically all I can do, wait to see if it happens again)