USB Bluetooth on Kubuntu 11.04 (Natty)

Diagnostic steps and commands for a USB Bluetooth adapter on Kubuntu 11.04 Natty Narwhal. dmesg, lsusb, hciconfig -a, rfkill unblock all, hciconfig hci0 up […]

(Fix) postfix: Recipient address rejected: Domain not found

We had a problem last weekend with Postfix not accepting email for a single domain when it was coming from outside our network, while messages from hosts on the local network were accepted and routed with no problems. Messages from outside the network were rejected with a 450 (temporary) code and the error message “Recipient address rejected: Domain not found”. The cause did end up being a DNS problem (apparently the most common kind of issue with Postfix), but not one that I would have expected (a missing host entry for the top-level domain, so wouldn’t resolve even though did). Finding the source of the problem was complicated because of a set of several changes during a weekend maintenance window.

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Configuring apcupsd on Linux for Multiple USB UPSes

I recently needed to add monitoring of a UPS powering network equipment to a Linux server already monitoring one USB-connected UPS. Since the second UPS also uses a USB connection for monitoring apcpusd (the standard UPS management package for Linux systems) was not seeing it. This is not a fault of the software – it’s designed to work pretty much seamlessly with detection of a single UPS and does so, but autodetectin multiple battery backups would still require some level of manual configuration – at the very least, which one(s) are powering the monitoring system in case it needs to shut down? The solution is to set up udev rules to let the system recognize each attached UPS as a distinct device using the serial number of the UPS, then follow the instructions for managing multiple UPSes in the manual. Continue reading Configuring apcupsd on Linux for Multiple USB UPSes

(Fix) Hangs When I Start Typing

I ran into a minor difficulty recently on a Linux desktop PC (CentOS 5.4) updated to the recently released 3.2, specifically the variant that includes some options and tweaks left out of the primary branch. 3.2 would start without difficulties, but as soon as I started to type the application would completely freeze up or hang. I only checked this in Calc and Writer, but I suspect that it applies to all of the other components as well and from what I’ve read it’s not specific to CentOS (or other RedHat-derived distributions).

After a bit of searching, I ended up at this thread: OpenOffice-3.0.1 hangs if SCIM is active. Boiled down to something for those not interested in the technical details, 3.x has problems with some configurations of SCIM, the “Smart Common Input Method platform.”
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