Tom Moertel's Weblog: Tag fedora

How to hotsync the Palm Centro with a Fedora 7 Linux desktop via USB

Tom Moertel — Wed, 31 Oct 2007 00:35:00 -0400

I just got a Palm Centro smartphone, and I love it. Getting it to sync with my Linux workstation, however, was tricky, so I’m posting this recipe in hopes that it might save you some time.

The “visor” kernel driver is supposed to make compatible Palm handhelds look like serial devices when attached via a USB cable. For me, it didn’t work. Instead, I had to blacklist the driver and then use libusb to talk to the Centro. Here’s the recipe:

First, blacklist the “visor” kernel driver:

# echo blacklist visor >> /etc/modprobe.conf
# modprobe -qr visor

Second, make sure libusb is installed:

# yum install libusb

Third, edit the system’s udev rules to make sure your user account can access the device files used to talk to the Centro. On my Fedora 7 setup, I found the right rule in /etc/udev/rules.d/50-udev.rules:

ACTION=="add", SUBSYSTEM=="usb_endpoint", \
ATTR{bEndpointAddress}=="?*", ATTRS{devnum}=="?*", ATTRS{busnum}=="?*", \
NAME="bus/usb/$attr{busnum}/$attr{devnum}_ep/$attr{bEndpointAddress}", \
MODE="0644", SYMLINK+="%k"

I edited the last line of the rule, changing the mode to 0664 and adding a GROUP key to assign the Centro devices to my exclusive user group:

MODE="0664", SYMLINK+="%k", GROUP="thor"

This change lets my account talk to the Centro without having to take on root privileges. (For bonus points you could set up a more-specific rule to match just your Centro. The rule above, as is, will actually match other devices, too.)

Fourth, tell udev to reload the rules:

# udevcontrol reload_rules

Finally, set up a Palm-device connection via gnome-pilot. Be sure to select USB for the Type and “usb:” from the Device drop-down list.

That’s it. If you’re lucky like me, you should now be ready to hotsync your Palm Centro!

Update: Even better, this handy HOWTO shows you to sync via Bluetooth, which is more convenient than hooking up a USB cable. I’m now using this method.

Update 2: If you want to use USB to hotsync your Centro, there is a method that’s more convenient than setting up udev rules. Just create a perms file for pam_console_apply that tells it to give the console user permission to access your Centro. To do so, create a file /etc/security/console.perms.d/60-libpisock.perms and put the following in it:

<libpisock>=/dev/usbdev* /dev/bus/usb/[0-9]*/[0-9]*
<console> 0644 <libpisock> 0644 root

That’s it. (You’ll still need to use libusb.)

New Fedora Core RPMS for CRAN packages arm, Matrix, lme4, car, coda, leaps, and mlmRev

Tom Moertel — Wed, 25 Apr 2007 14:07:00 -0400

Just a quick note for folks using the R statistics system on Fedora Linux. I have packaged for Fedora a bunch of R packages from the CRAN. (R packages have to be packaged again, as RPM packages, to integrate with Fedora Linux.)

My initial goal was to package arm, which contains tools for working with various regression models. (This package accompanies Andrew Gelman and Jennifer Hill’s wonderful book Data Analysis Using Regression and Multilevel/Hierarchical Models.) Packaging “arm,” however, quickly snowballed into packaging a bunch of prerequisites. Thankfully, I have now completed that task and can share the fruits of my labor with you.

All in all, to install “arm,” you will need the following RPMs:

R-arm-1.0-2
R-car-1.2-1
R-lme4-0.9975-1
R-Matrix-0.9975-1
R-R2WinBUGS-2.0-1

The following RPMs are optional (but you will need them if you want to rebuild the RPMs):

R-coda-0.10-1
R-leaps-2.7-1
R-mlmRev-0.995-1

You can download the packages from the RPMs section of the Community Projects site. Better yet, you can use Yum to download them for you. Just add the moertel-community Yum repository to your /etc/yum.repos.d directory (see RPMs for the recipe) and then use the following command:

$ sudo yum install R-arm

Yum will automatically resolve dependencies and install the required packages. If you want any of the optional packages, add them after “R-arm” on the command line.

I have built the packages for Fedora Core 6 on the x86_64 architecture, but the RPM specs are available if you want to rebuild the packages for other architectures. (See the instructions for rebuilding RPMs for help.)

Caveat: I’m not sure that the R-R2WinBUGS package is fully functional. It depends on BRugs, which doesn’t yet build on the Linux platform. To get around this problem, I made R-R2WinBUGS’s dependency on BRugs weak; the first package no longer requires the second to install.

Engauge Digitizer: a handy tool for extracting data from charts

Tom Moertel — Tue, 17 Apr 2007 03:45:00 -0400

Today I wanted to extract the data that were visualized in a chart I saw on Seth Roberts’s blog. That is, I had a picture of a data set, and I wanted the numbers behind the picture.

This task turned out to be surprisingly easy – once I found Engauge Digitizer, an open-source (GPL) tool made for this very task. After I launched Engauge, the digitization process was straightforward:

I established the chart’s coordinate system by clicking in the corners and entering the associated coordinates.
Then I had Engauge identify data points. With the mouse, I selected a data point by hand, teaching Engauge what a point looks like. Then Engauge identified spots on chart that looked like data points and locked on to them. I was able to step through the points to tell Engauge to skip the few it misidentified.
I manually selected a few more data points that were scrunched into blobs and had eluded Engauge’s point-detection heuristics.
Finally, I exported the data set in CSV format.

If you ever need to extract the data behind a chart, do check out Engauge Digitizer. (If you use Fedora Linux, you’ll be happy to know that I have packaged Engauge for you. Get it at the RPMs section of the community site.)

How to make sure your servers come back up after an extended power outage

Tom Moertel — Wed, 09 Aug 2006 00:35:00 -0400

If an extended power outage drains your UPS, and your servers are forced to shut down, will they automatically start up again when the power is eventually restored? It’s a good question, especially if your servers are in some distant, unattended server room. Unless you’ve tested your servers, don’t assume that the answer is Yes.

Many servers offer a BIOS configuration option that forces them to automatically power on when they receive line voltage. If your servers have this option, just set it and you’re done.

Unfortunately, some servers, including a Dell PowerEdge 1600SC that I’m using, lack this configuration option. When these servers turn themselves off as the final step of a UPS-controlled shutdown, they don’t start up again when the power is restored. Because they were shut down before the power was cut off, they think they are supposed to remain off when the power is restored. That is, they remember their on/off status across power outages.

Fortunately, there is a way to make sure these servers automatically power on: shut them down without powering them off; halt them instead. That way, when the UPS finally cuts off the supply voltage, the servers will still be in their “on” state, and they will remember this state across the outage. Later, when the power is restored, the servers will automatically restore their pre-outage state and power up.

With Fedora Core Linux and Network UPS Tools, it’s not difficult to make sure the servers are halted instead of powered off, but the implementation isn’t obvious. To spare you the digging, here are the important bits.

When the power fails and the UPS-monitoring software decides that the batteries are almost depleted, it will initiate a server shutdown using the command defined in the /etc/ups/upsmon.conf file. The default command is this:
```
SHUTDOWNCMD "/sbin/shutdown -h +0" 
```
The shutdown command will tell the init process to enter runlevel 0, which is the prepare-to-halt-the-system runlevel.
The init process will stop all of the running services in an orderly fashion, and then, as the last step, invoke the final script in the shutdown process: /etc/rc.d/rc0.d/S01halt.
The final lines of the S01halt script will power off the server. Unless, that is, the file /halt is present, in which case the script will halt the server instead.

Thus the trick is to make sure that the /halt file does exist. The trick turns out to be easy to pull off; just redefine the shutdown command in /etc/ups/upsmon.conf:

SHUTDOWNCMD "/bin/touch /halt; /sbin/shutdown -h +0"

And that’s all there is to it!