Parallel Universe

It is really worth reading the article “Future of RDBMS is RAM Clouds & SSD”. Will RAM be the DISK of the FUTURE and DISK the TAPE of the future?

Source: Stick animations!

Very funny videos for those who have experienced to work with computer tech support

Problem:

Ubuntu starts up automatically on the graphic mode. This is a nice features for most of the users but I am running Ubuntu on a VM and would like to have it directly to the command prompt and decide myself (by startx command) to start the graphical interface if I want.

Every linux system has a certain number of runlevels. The system boots up and goes enabling services whenever getting at each runlevel.

As an example, in popular linux distributions such as Fedora the runlevel 1 is single user mode, 2  multi-user without network, 3 full multiuser console mode, 4 is reserved and 5 is the graphical mode.

So, in order to give maintenance on the system you would simply boot on runlevel 1 and have single user mode. Normally the user will be either in runlevel 5 (graphical interface) or 3 (full console/text interface).

In Fedora it is fairly easy to change your runlevel by editing /etc/inittab and changing the line:

id:5:initdefault:

If you want to go for text mode you simply change the 5 for 3:
id:3:initdefault:

What about Ubuntu?

My problem would be solved if Ubuntu followed the same philosophy of Fedora but this is far from being true. First of all Ubuntu does not have the /etc/inittab file.

You can change the runlevel by running the command (as superuser):

root@server:$ telinit 3

But this will not help because from runlevel 2 on Ubuntu is already in graphical mode. Also the default runlevel for Ubuntu is 2.

Solving the problem

One possible solution for this problem is to disable the graphical service in runlevel 2. This is the default runlevel at Ubuntu and whenever we want the default to be back in graphic mode we can simply change the runlevel to 3.

Disabling GDM

In order to disable the graphical mode in runlevel 2 (the default one) we will simply disable the GDM service by renaming it with the command:

user@server:$ sudo mv /etc/rc2.d/S30gdm /etc/rc2.d/K30gdm

This will mean that instead of starting (S) the service GDM it will  kill (K) this service.

What about the upsplash screen?

Yeah, I know. Although now we boot up on the console, we still see the graphical splash screen while booting up.

To disable that you will need to change the boot loader configuration. Don’t worry, it is very simple.

Just edit the file /boot/grub/menu.lst

user@server:$ sudo vim /boot/grub/menu.lst

Take the “splash” word out from the line (something like that):

kernel /boot/vmlinuz-2.6.27-14-generic root=/dev/hda1 ro quiet splash

That is it.

I have one of these usb tv card from Hauppauge and survive all the trouble that it brings me. The last one was the fact that it comes with a webserver that I completely dislike once the computer I have the tv cad is my server that also will have an webserver.

So, what if you want to disable your Hauppauge’s webserver?

You will need to go to windows control panel and administrative tools. Select then “Services” and stop the service “EPGService”. In order to avoid it from starting over the next time you boot up your computer, make sure you double click on this service and put its startup to “manual”.

I am currently setting up a home server (actually a virtual home server) for all my personal software projects.

I have one TRAC for each project and one svn repository for all projects.

Then I got the problem of interfacing svn and TRAC. The script TRAC offers for making this interface is a python post-commit hook that you add on you subversion hooks. This script assumes you have the repository targeting one trac project (that is set by TRAC_ENV).

But this was not my case. So, I needed to set TRAC_ENV depending on the project I was doing the commit.

In order to do that I changed the post-commit script to get the project and add the project name to the TRAC_ENV. So I now point out to the TRAC that corresponds to the project being updated on my subversion.

My post-commit hook is then:

REPOS="$1"
REV="$2"
PROJ=`svnlook changed /srv/svn/repo | head -n 1 | sed 's/.* //' | sed 's/\/.*//'`
TRAC_ENV="/my/trac/base/$PROJ"
/usr/bin/python /srv/svn/repo/hooks/trac-post-commit-hook.py -p "$TRAC_ENV" -r "$REV"

By the way, make sure your svn user can write to the TRAC database. My trac data is owned by the group www-data so I just did add svn to the www-group and changed the file permissions:

sudo chmod g+rw /my/trac/base/* -R

PS.: If you just want to interface a subversion repository with a TRAC then follow the instructions in here.

Simple command to know which version of Ubuntu you are running:

me@ubuntu:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=8.04
DISTRIB_CODENAME=hardy
DISTRIB_DESCRIPTION="Ubuntu 8.04.1"
me@ubuntu:~$

If you live in a foreign country like me, you may have already found the streaming site Justin.TV. This site broadcasts the streams of its users and many of them are from local television.

Through Justin.TV I can watch the events my local TV does not show, like the Argentina x Brazil match from yesterday.

There is one inconvenient though. Justin.tv is limiting the bandwidth for some countries (the one I live included) and after a short while you are watching, the channel will stop and display a message: “We’ve reached the maximum number of streams for your country…”.

One way to avoid this behavior is to use a proxy. In other words, your computer will ask for data from another computer that is in a country for which justin.tv does not limit the bandwidth. For justin.tv you are not watching anything, it is the other computer that is doing it.

As you can see, the use of a proxy is also interesting when you want to surf the web without being noticed.

How to set up a proxy?

If you use Internet Explorer I recommend the program UltraSurf. You download the program, run it and it will open an Internet Explorer under a proxy. To configure the proxy, in UltraSurf, you select “options” and then “proxy settings”.

The proxy I am using and that is so far working fine is: 174.142.24.201 with port 3128

If you use Firefox, just go on Options->Advanced->Network->Settings and configure a the mentioned proxy at “Manual proxy configuration”.