Install kernel headers in linux using aptitude

sudo aptitude install linux-kernel-headers linux-headers-`uname -r`

Conversion of CR+LF to LF

The following will convert all files also in subdirectories
exept for those starting with a dot (skips also such directories).
This works if dos2unix is available, of course; otherwise use sed.

find ^.* -exec dos2unix '{}' \;

I needed it to convert the content of a git repository (that's
why I skipped the . files: I didn't want .git/* files to be included).
Of course you can write better matching chriteria, but this worked
fine for my case.

Turn colors on in vi/vim

If the color syntax highlighting is off, you can turn it on by editing (or creating) ~/.vimrc, adding the following line:

:syn on

Determine the current runnning shell (linux)

echo $SHELL

bash startup

In interactive mode bash executes some startup scripts. First thing to know is if it is a login shell or not a login shell: 

* login shell: (executes more things)
(1) general settings for all users are in: /etc/profile
(2) personal settins may be in: (first one readable)
~/.bash_profile
~/.bash_login
~/.profile
(3) before logout: ~/.bash_logout

* non-login: 
>bash => ~/.bashrc

>bash --norc => nothing
>bash --rcfile filename => specify another rc file