Is my kernel 32 bit or 64 bit

In linux, we often see the use of ./ or ../ before a file name. Here is the explanation for the same

.  Current Directory
.. Parent Directory

./filename  # referring to file name in current directory
../filename # referring to file name in p...

I've noticed that Incognito mode retain cache from the previous session, it just don't collect any new cache while in incognito.

I usually clear the cache/cookies then go into incognito, or run a different browser profile, or a different browser ...

In ubuntu, you have a variety of window managers to choose from. Though Ubuntu 12.04 comes with Unity as the default you can switch back to Gnome, or choose other managers like Cinnamon.

If you want to know, which window manager you are running c...

This is to install adobe flash player in Ubuntu 14.04 or higher. This works for Firefox browser.

If you have a 32-bit OS, run

sudo apt-get update
sudo apt-get install flashplugin-installer

Make sure each of the commands executed success...

To check if a given package is installed in Debian / Ubuntu, type

dpkg -s <package-name>

To get a neater output use dpkg-query which accepts wildcards as well.

dpkg-query -l <package-name>

In Redhat / Fedora / CentOS use the foll...

In Ruby, send is often introduced as a way to show how everything is an object

1.send(:+, 1)  ## -> 2

It can also be used to call private or protected methods from outside a given class as explained below.

class Myclass
  def method...

To delete sessions based on a hard coded cut-off date:

DELETE FROM sessions WHERE updated_at < STR_TO_DATE('23.05.2013',GET_FORMAT(DATE,'EUR'));

Replacing cut-off date with period of inactivity

DELETE FROM sessions WHERE updated_at ...

To get formatted results for select statements use \G as a suffix for the query.

select * from table_name\G

Use following command and answer YES to enable dynamic updates:

sudo dpkg-reconfigure resolvconf

Do a system restart after that.