Dropbox installation from the command line

In order to install dropbox from the command line, follow the instructions found here. Useful in case your system is stuck with an old, broken version...
If by any chance you want to install dropbox on a centos system, then this will probably be of use.

It seems that centos has some issues with dropbox client v3. Here is a discussion about it

SELinux in redhat (and friends) systems

If you wonder what SELinux is, you my find this useful. If you ever find yourself wanting to disable SELinux, just set it in permissive mode instead,so you can at least have its logs to use in case something weird happens. Also this blog post gives a nice overview of what SELinux is all about

Molecular Mechanisms of Learning and Memory, by Lee Frank

I have started reading this short essay related to the mechanisms and different types of learning at a molecular level. Fascinating stuff, that make digital communications seem simplistic.

su user cannot open display

Sometimes you want to run something graphical as a different user on your system and when switching to that user using su you get the error "cannot open display"

There are a number of solutions to this problem.
The simplest one (but a bit insecure) is to run xhost + before switching users.
This will disable the authentication mechanism of X windows.

Update postfix virtual address map

You just need to use the command sudo postmap ./virtual in /etc/postfix if your virtual db file is called virtual.

Of course you need to have this activated in the /etc/main.cf using the variables:
virtual_alias_domains and
virtual_alias_maps

if you changed anything in the main.cf you also need to do a postfix reload.

The Hobbit 3. The battle of 5 armies

Watched this in IMAX 3D. Not bad at all, i have the feeling that the whole production was slightly better than the first and the second.

After the history of Florence, SuperFreakonomics

After the history of Florence by Machiavelli, i have started superFreakonomics, a more relaxed reading of unconventional stories related to economy of culture. Some of them are really funny, some are not, but most of of them are at least unexpected.