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I like it when things work, but I also like it when I know why things have started working.
My server machine, azathoth, runs Linux. Indeed, since I built the box up from components (probably the only time I will do this, to be honest - it's not my idea of fun) it has only ever had Linux on it. I first installed SuSE Linux on it, which ran everything fine. In particular, the SCSI devices attached to azathoth worked flawlessly for all users - the CD-R and scanner could be invoked using user space tools, because I had figured out the permissions necessary for the devices.
However, I was dissatisfied with SuSE Linux in this application. I still think that SuSE is a fine workstation distro, if only because it comes with so many toys, but I dislike it as a server distro because it's a pain to setup minimally enough for a server. I want as few services running as possible, because fewer services mean fewer security holes. SuSE installs a lot of stuff by default, and I would rather work to choose what I want than choose to exclude what I do not. I had also found that I couldn't easily upgrade the kernel or the filesystem support, or any other of a myriad other things that I would need to buy a newer version of SuSE to fix.
So, I switched azathoth over to Gentoo Linux. This is a nice distro with a lot of neat features for the control freak hacker. One of these is that packages are distributed in source form and then compiled locally which means they are always compiled according to the local system choices. Another, and the one that is relevant here, is that when first installed the distro does bugger all. You need to make a positive choice about what to install, which means you have a lot more control over what runs. I knew what tools I needed and had the necessary network connections for our home network backups up and running pretty quickly.
The problem I had was in getting all the attached devices working. Once I'd figured out that one of the SCSI cables wasn't plugged in properly, I at least had the CD-R functioning as desired. But making the scanner work properly eluded me - I got to a point that the root user could scan, but that's not much help really. I've kept SuSE Linux around for this specific purpose, which is annoying in itself. It's untidy.
One of the things I decided to try and finally fix last night when my ankle was bothering me was this scanner non-functioning. I knew it was a permissions issue, so I started rummaging around for more information on setting permissions in devfs (the device management scheme which Gentoo uses). Once I'd read a bit, I thought I'd try out some of the suggestions and so I needed to find out which SCSI device the scanner was attached to.
The scanner software I use is SANE, which comes with a tool called sane-find-scanner which fits the bill, and I ran it. I accidentally ran it using my user account, and was rather surprised when it found a scanner. This gave me the answer I was looking for, but I hadn't expected it to work at all.
Basically, the scanner software had fixed itself.
I still don't know what had changed to fix the scanner permissions. It wasn't anything I had done last night, certainly. Maybe some of the thrashing around I did before stuck (devfs does some tricky things around preserving permissions), or maybe a package update of the scanner software or the devfs drivers had addressed the permissions problems without my intervention.
Either way, I am glad it works but I am dissatisfied because I don't know why.
Still, at least I can get rid of SuSE and some of the stale Gentoo installs that are still hanging around from past adventures. That's a result if nothing else is!
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Posted by Dunx at May 6, 2004 01:44 PM
Not knowing is always ultra-frustrating, but sometimes you just have to accept with good grace whatever gifts the universe bestows on you :)
Well, there's that of course. On the other hand, if I do not know why it works I also will not be able to stop it breaking!
But I'll try and be gracious. It's not one of my special skills, though, grace.
I disagree as to that last bit. Re-reading my comment it does seem rather rude -- apologies for that, I didn't mean to suggest you were being ungracious. Au contraire.
I think that we are both good at being hard on ourselves - both of us are more talented than either would publically admit to ourselves. If I made New Year resolutions, then resolving to be less self-critical would be high on the list every year.