or checking out a specific commit.

First, one has to locate the hash of the commit. This can be done by:

1. Scanning the log by running “git log” (press q to quit). Look for lines labeled commit.
2. Scanning the log in giggle. Look for the SHA-line. Example:
   

In this case our hash is 7f8d2051582dd030e3c07ded70010af033461e31.

Then, come up with a name for a branch to refer the this specific revision. For this example we will use old-branch.

Last, set up the branch by running:

git checkout -b old-branch 7f8d2051582dd030e3c07ded70010af033461e31

Syntax: The general syntax is: “git checkout -b BRANCHNAME HASH“

Since installing Karmic on my laptop, it has consistently failed to connect to the World Community Grid server.

Symptoms: When going the the ‘Messages’ tab of the ‘Advanced View’, one is greeted by lines of the form:

2009-11-05T12:56:47 CET|World Community Grid|Sending scheduler request: Project initialization. Requesting 1 seconds of work, reporting 0 completed tasks
2009-11-05T12:56:50 CET||Project communication failed: attempting access to reference site
2009-11-05T12:56:52 CET|World Community Grid|Scheduler request failed: Peer certificate cannot be authenticated with known CA certificates
2009-11-05T12:56:53 CET||Internet access OK - project servers may be temporarily down.

Solution: After some googling I came across this page, which basically gives a simple workaround:

sudo su
cd /var/lib/boinc-client
mv ca-bundle.crt ca-bundle.crt.backup
wget http://boinc.berkeley.edu/trac/export/16195/trunk/boinc/curl/ca-bundle.crt

I’m not convinced that it will survive an update though.

From time to time one needs to measure stuff on the desktop. You might – for instance – want to know whether some region of an image will fit nicely into some part of a webpage.

In ubuntu (both jaunty and karmic releases) the screenruler application provides an easily available mean to do just that. This application is available through a package of the same name and can be found in the menu under Applications -> Accessories -> Screen Ruler.

The screenshot above shows two instances of screenruler along with the contextual menu (available through right-click or a menu button which appears when the mouse hovers over the ruler). Through this menu the metric can be changed. The length of the ruler can be changed by pulling in the ends and the orientation can be flipped by middle-clicking.

Note: This applies to multiple flavors of Ubuntu; Jaunty as well as Karmic. Also, it might be generic to all distributions based on Network Manager.

At the university we have a eduroam-based wireless network. It has not been very dependable yet; sometimes you can log on, sometimes you cannot. It doesn’t seem to be directly related to signal strength.

It seems that Ubuntu – which uses Network Manager – is quite well suited for this environment. Our setup is based on two laptops; one which can connect to eduroam and one which cannot. These are connected by a standard ethernet cable. The laptop connected to eduroam is then set up to share the connection.

The Guide

First open up the network connections dialog. Do this by right clicking on the Network Manager icon in the notification area and choose ‘Edit Connections …’. In the ‘Wired’ tab, click ‘Add’ to add a new connection. Fill it out like so:

The important parts are

1. The method. This should be ‘Shared to other computers’.
2. The unmarking of ‘Connect automatically’. This will make sure other connections (like DHCP) take precedence.

After confirming this dialog (by clicking ‘Apply …’) the list of network connections should look like this:

Thats it! When you whish to share a wireless connection, click on the network manager icon in the notification area and choose ‘Share Connection’ under ‘Wired networks’.

The solution for Jaunty seems to have degenerated.

I recently installed Karmic (Koala) Beta and decided to give it a try again. For me, installing the pidgin-facebookchat package and following the instructions at the relevant (bottom) part of the official documentations page regarding protocols. The experience is not entirely stable, but for a beta release I guess it’s ok.

Not the Darwinian kind, but the mail client. This is useful if you want to move evolution data back and forth between two machines.

A little google-research seems to indicate that Evolution stores its data at several locations:

• Running processes These may interfere with our work.
  Exit them by running: killall evolution-data-server-2.26 evolution-alarm-notify
  Note that the name of the data server seems to follow the relase of evolution (2.26 in this case).
• ~/.evolution This is the big one, containing mails and other kind of data.
  Backed up by running: mv ~/.evolution ~/.evolution.bk0
  Note this resets the location.
• ~/.gconf/apps/evolution Contains GConf data. This is most likely and old format which I have lying around.
  Backed up by running: mv ~/.gconf/apps/evolution ~/.evolution_gconf
  Note this resets the location.
• gconf2://apps/evolution Contains GConf data, new format.
  I don’t know how to backup this.
  Removed by running[source]: gconftool-2 --recursive-unset /apps/evolution
  Note this resets the location.

When these locations have been cleared, starting evolution will launch a settings importer, which can load settings from a backup. Backups can be created by chosing ‘Backup Settings …’ from the ‘File’ menu.

Note: This process appears to forget all about your signatures. Use other means to back them up if necessary.

Came across an article describing one guys efforts in photographing bats slurping water from a pond while in flight. The pictures are strangely beautiful.

Locating clear guidelines describing the proces of creating a copy of an already existing machine (also known as cloning it) is not an easy task. I gave up when I came across an unofficial guide or two.

In VirtualBox, virtual machine definitions are stored separately from disk images. Cloning the machine can be reduced to the matter of cloning the disk(s) and creating a new machine which uses the cloned disk(s). Since disk images contain a unique identifier (UUID) a simple copy – as performed by the operating system – won’t do. Instead, use the following command:

vboxmanage clonevdi ORIGINAL_IMAGE NEW_IMAGE

The default locating for disk images is ~/.VirtualBox/HardDisks and the files use the .vdi extension.

Example:

$ vboxmanage clonevdi ~/.VirtualBox/HardDisks/Disk.vdi ~/.VirtualBox/HardDisks/DiskClone.vdi
VirtualBox Command Line Management Interface Version 2.1.4_OSE
(C) 2005-2009 Sun Microsystems, Inc.
All rights reserved.

0%...10%...20%...30%...40%...50%...60%...70%...80%...90%...100%
Clone hard disk created in format 'VDI'. UUID: cd4972c2-b57f-4b59-90f3-db151ac131e5
$

Then create a new virtual machine which uses the DiskClone.vdi image.

This site sells kits to convert Leica R-Mount lenses to Nikon F mount.

Features (according to site):

• The procedure is fully reversible.
• The lens will focus to infinity.
• Nikon cameras will show focus confirmation light in viewfinder.

It seems like a few Hong Kong based brands are offering alternatives on ebay. Don’t know if they are trustworthy though …

leitax also has kits for other exotic lens/body combinations. Just about any combination of:

• Lens: Contax Carl Zeiss, Leica R
• Body: Canon EOS, Minolta/Sony alpha, Nikon F, Pentax, Sigma

Chilean coup d’état