Mao PU's digital scratchbook for anything.


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Performance Evaluation, Measurement and Characterization of Complex Systems (Raghunath Nambiar, Meikel Poess)

Ubuntu with broken boot (partition)

Within the last 3 months I’ve had several incidents, where Ubuntu systems booted into a Busybox. In all cases booting a live CD and repairing the file system with `fsck /dev/sdx`, answering several times with “yes” fixed the problem.

Since I installed some customers machines that are physically located quite a few miles away, I am afraid, this error will lead to me, driving there, inserting the live disk, typing the above mentioned command and driving back…

Never heard of other systems with similar problems - so what is this?

git and subversion parallel

I work on some projects that are shared across developer sites via a centralized subversion repository. These projects use svn:keywords to track last changes, revisions and responsibilities.

Since I have a much higher commit frequency than most of my colleagues but do not want to create too much noise on the central repository, I decided to use git locally to track my personal changes. Some of the projects include personal configuration files, that are not allowed to be exchanged with other developers (e.g. eclipse .project files). Nevertheless I wanted to track changes in these files as well.

I was experimenting with git-svn a lot, tried to create scripts that imitate the svn:keyword usage of our projects. After several hours of getting into plumbing and porcelain I finally decided, that the project I am working on are not really the best use cases to start with git-svn (or git at all).

Right now, I set up both systems in parallel for the projects. In .git/info/excludes I put .svn and .git is in svn:ignore. I can independendly decide, when to commit and checkout, can easily branch and save intermediate results using git and spare my colleagues the hourly update on my work :-)) Whenever I check update subversion, I do this in a git branch. Afterwards I merge the branch with my work and commit the result to subversion. The only thing that is still not optimal, is the noise created by svn:keywords in the git repository - but this is something I can live with by now.

I wonder, if there are any side effects in the long run, but for now the parallel installation seems an even better solution for my projects than the git-svn could be. Sorry for these heretical thoughts…

Export / Import applicance error on VirtualBox

If you have trouble importing an applicance you just exported from a lower version of VirtualBox, read the linked post and use the VBoxFixHdd tool to repair the disk images.

Disable firefox DNS cache

DNS caching in the browser is not usefull if you machine is caching the dns some place else. Disable it in FF by entering network.dnsCacheExpiration=0 and network.dnsCacheEntries=0 at about:config

dirty configuration for tld on localhost

To develop a site, that depends on the correct domain name, I had to redirect to my local apache.

I did not find a good solution, already asked for help on serverfault more than a week ago on an similar question.

Today I finally got dnsmasq up and running (using openresolv, a resolvconf-clone). I created a file with all the necessary entries:
and also created VirtualHosts for each of the domains. I am sure, there is a better way doing this using mod_rewrite and such, but for now it works….

Suggested reading for DHCP

I just suggested Tanenbaums book on networking as an answer to Superuser.

Cross browser opacity

not yet tested, but there seems to be a certain order for IE opacity definition.