Introverts

So I just stumbled across a video about introverts and thought I'd share it.

Creating a DVD

Creating a DVD is easy but also harder then it needs to be. I wish I could just say "I have an NTSC TV. I have an .avi over there. Make it so." But alas there are all sorts of fiddly bits that need dealing with. So I need a GUI front end that understands the fiddly bits. But installing on CentOS one can get complicated.

First you need CentOS 6.

Then you need ffmpeg 0.7, available from the NauLinux school repo. You might already have ffmpeg 0.6.5 installed, in which case you'll need rpm -e ffmpeg-libpostproc --nodeps before doing yum --enablerepo=naulinux-school install ffmpeg. (If you skip this step, you end up with an error that looks like Unrecognized option 'vf'. Or at least you will if can find stderr, which might be in ~/.xsession-errors).

Finally you install devede, which is written in Python but is surprisingly non-fail. Linux tech has a repo. Set up that repo, then run yum --enablerepo=linuxtech-testing --enablerepo=rpmforge install devede.

Vixie is a smart guy

I found out something interesting the other day. A crontab entry has a DOW (day of week) column and a day of month (DOM) column. Because I'm a bad sysadmin, I'd never read the full manpage and assumed that if you specified both your entry would be run once every 7 or 14 years. I also suffer from NIH, so I'm writing a cron replacement in pure-perl that includes all the stuff I think a cron should have, like watching a directory for new files. So I finally read the full man page. And it turns out that Vixie was a smart guy. Having an cron job that runs every 7 or 14 years isn't useful so the DOW and DOM columns don't affect each other.

I other words

0 0 1 * 0 do-something

is in fact the equivalent of

0 0 1 * * do-something
0 0 * * 0 do-something

which is so much more useful.

This is another formulation of the "don't allow the user to do stupid things" principle I talked about a while back.

Total silence

I bought myself a fanless PSU for my birthday. I'd been eying one for a while now. Corey now has no fan on the CPU, a SSD and a fanless PSU; total, deafening silence. I had to move Corey into a different case because the PSU wants to be vented from the top. So now I've changed corey's CPU, motherboard, heatsink, hard drive, RAM, case and PSU. But it's still the same ax!

Of note: when you switch on a computer you've just assembled, one of the first bits of feedback you get is the fans going WUURRRwuuurrrrr. But not if your computer has no fans! It took me at least one panicky minute to figure this our.

Gloating

I just have to share this:

~ (fil@billy:)$ uptime
 13:48:21 up 719 days, 13:48, 11 users,  load average: 0.37, 0.22, 0.18

This means my rented VM host hasn't been rebooted in close to 2 years. Wheee!

Multiple UPSes

OK, so now for a problem that probably only affects me. I have multiple UPSes in my server closet. A large one (APC BackUPS XS-1300 LCD) for most of the computers in the closet and a mid-sized one (APC BackUPS XS-900) for the computers in my office. I have a long wire running through the floor into my office. Why not put the mid-sized one in the office itself? Because it has a noisy fan.

Both these USPes are connected via USB to one computer. This computer assigns nearly randomly the device name, based on where I've plugged them into a USB hub. This resulted in the computers in the basement thinking they were on the 900 and my office thinking it was on the 1300. Not acceptable.

Using lsusb, I see the UPSes are at 2:5 and 2:4

# lsusb
Bus 004 Device 001: ID 0000:0000  
Bus 003 Device 001: ID 0000:0000  
Bus 005 Device 001: ID 0000:0000  
Bus 001 Device 001: ID 0000:0000  
Bus 002 Device 005: ID 051d:0002 American Power Conversion Uninterruptible Power Supply
Bus 002 Device 002: ID 05e3:0604 Genesys Logic, Inc. USB 1.1 Hub
Bus 002 Device 001: ID 0000:0000  
Bus 002 Device 004: ID 051d:0002 American Power Conversion Uninterruptible Power Supply

Again with lsusb, I can find the serial number:

# lsusb -v -s 2:5
Bus 002 Device 005: ID 051d:0002 American Power Conversion Uninterruptible Power Supp
ly
Device Descriptor:
  bLength                18
  bDescriptorType         1
  bcdUSB               1.10
  bDeviceClass            0 (Defined at Interface level)
  bDeviceSubClass         0
  bDeviceProtocol         0
  bMaxPacketSize0         8
  idVendor           0x051d American Power Conversion  
  idProduct          0x0002 Uninterruptible Power Supply
  bcdDevice            1.06
  iManufacturer           3 American Power Conversion
  iProduct                1 Back-UPS XS  900 FW:830.E8 .D USB FW:E8 
  iSerial                 2 BB0842016813  
... SNIP ...

Another way to get the same info:

# udevinfo -a -p /class/usb_device/usbdev2.5
  looking at device '/class/usb_device/usbdev2.5':
    KERNEL=="usbdev2.5"
    SUBSYSTEM=="usb_device"
    SYSFS{dev}=="189:132"

  looking at parent device '/devices/pci0000:00/0000:00:1d.0/usb2/2-1/2-1.3':
    ID=="2-1.3"
    BUS=="usb"
    DRIVER=="usb"
    SYSFS{configuration}==""
    SYSFS{serial}=="BB0842016813  "
    SYSFS{product}=="Back-UPS XS  900 FW:830.E8 .D USB FW:E8 "
    SYSFS{manufacturer}=="American Power Conversion"
    SYSFS{maxchild}=="0"
    SYSFS{version}==" 1.10"
... SNIP ...

Then I created some custom udev rules in /etc/udev/rules.d/99-apc.rules:

KERNEL=="hiddev*", SYSFS{serial}=="BB0842016813*", NAME="apc900"
KERNEL=="hiddev*", SYSFS{serial}=="JB0741003708*", NAME="apc1300"

I could also have used SYSFS{product} for matching, but the serial number uniquely defines these UPSes. I need the * for globbing because the serial number is padded with spaces, as can be seen in the udevinfo output.

Next reload the udev db:

# udevcontrol reload_rules
# udevtrigger
# ls -l /dev/apc*
crw------- 1 root root 180, 97 Oct  5 12:53 /dev/apc1300
crw------- 1 root root 180, 96 Oct  5 12:53 /dev/apc900

YAY!

Today in scamming news

They got shut down.  I don't know if it's the scammers that have phone me and Papy.