The default desktop environment for Ubuntu 11.04 (Natty Narwhal) Unity. While Unity itself is great, some might prefer the old GNOME 2.8.x desktop environment.

In Natty Narwhal, GNOME 2 is installed by default. To login to GNOME 2 session instead of Unity, follow these steps;

sudo is a program that allows a user to run programs with the security privileges of another user. If no user is specified, it will try to run the other program as root, or the superuser. By default, running sudo will prompt for the superuser password, as in the following example;

shakir@anduril:~$ sudo vi /etc/resolv.conf

 We assume you have received the usual lecture from the local System
 Administrator. It usually boils down to these three things:

 #1) Respect the privacy of others.
 #2) Think before you type.
 #3) With great power comes great responsibility.

 Password:

While this is good for security reason, normal users would want to avoid the password prompt completely, especially if they are just running it on a desktop.

To enable passwordless sudo, one need to edit the /etc/sudoers file. This can be done by directly editing the file using your favorite editor as the following;

$ sudo vi /etc/sudoers

or by using a dedicated program just for this by issuing the following command;

$ su -
# visudo

In editing the file, there are 2 options to enable passwordless sudo, which is to allow by group, or by user.

To everyone in the group mygroup to be able to use sudo without password, add the following line;

%mygroup ALL=NOPASSWD: ALL

Adding the following line will allow the user shakir to use sudo without password

shakir ALL=NOPASSWD: ALL

The default display (login) manager for Ubuntu/GNOME is GDM. KDM, which is the login manager for Kubuntu/KDE is installed when you install the kubuntu-desktop package in your Ubuntu system.

If you want to switch back to GDM as the login manager, run the following command at the terminal;

sudo dpkg-reconfigure gdm

At the ncurses menu, choose gdm and click OK.

You’ll now be presented with GDM every time you boot your Ubuntu system.

Google AdSense by default serve ads based on your visitor’s browsing history that Google stores in browser’s cookie. Depending on your website’s niche, disabling it can serve more targeted ads to your visitors and increase your AdSense earnings.

A niche with high competition in Google AdWords (where there are a lot advertisers bid for keywords in your site) would benefit from disabling the option, while site’s with less targeted keyword might suffer.

To disable 'Interest-based ads, go to Allow & block ads → Advanced settings from your Gooogle AdSense dashboard.

From there, disable the interest-based ads in the Interest-based Ads Preferences section.

You could get the following warning if timezone is not configured for PHP when using date related function such as date() or date_default_timezone_get().

You can configure timezone for PHP by setting up date.timezone in your configuration file to any of the supported timezones. You can view the list of supported timezones from PHP‘s official documentation.

The following example sets the timezone to America/Los_Angeles

[Date]
; Defines the default timezone used by the date functions
; http://php.net/date.timezone
date.timezone = America/Los_Angeles

If you’re using PHP 5.1.0 or later, you can you can independently set the timezone for each of your PHP script by calling the date_default_timezone_set function with the timezone as the parameter.

bool date_default_timezone_set ( string $timezone_identifier )

The example below sets the timezone for the rest of the script to America/Los_Angeles.

<?php
date_default_timezone_set('America/Los_Angeles');
?>

Don’t forget to restart your webserver after changing the PHO configuration file for the changes to take effect.

There are a number of programs that you can use to view running processes in Linux, and generally every desktop environment will include one of their own. GNOME for example comes with GNOME System Monitor while KDE has System Activity. For all Linux distributions however, you can use always go to the command line and use both ps and top.

You will get the following [Process completed] message when exiting the session in Terminal and will have to manually close the Terminal windows afterwards.

Saving session...completed.

[Process completed]

Follow these steps to avoid the message and let the window automatically close.

1. Open the Preferences window from the menu.
   
2. Go to the Profiles tab and choose the profile that you want to set this option on.
   

   Basic is the default profile and it’s safe to just select it if you can’t remember ever changing the profiles settings.

3. Click on the Shell tab and find the When the shell exits option.
   
4. Choose Close if the shell exited cleanly from the option’s select list.
   

SSH by default will check and keep key fingerprint of all the hosts you’ve connected to in ~/.ssh/known_hosts. You’ll get the following warning if the fingerprint changed from the last time you’ve connected to the host;

@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED!  @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@

IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that the RSA host key has just been changed.
The fingerprint for the RSA key sent by the remote host is
11:5b:16:56:a5:cd:9b:1e:11:aa:2b:1c:a2:91:cd:a2.
Please contact your system administrator.
Add correct host key in /home/user/.ssh/known_hosts to get rid of this message.
Offending key in /home/user/.ssh/known_hosts:1
RSA host key for docs.oseems.com has changed and you have requested strict checking.
Host key verification failed.

You can fix the problem by whether disabling the key check, or have the right key in your ~/.ssh/known_hosts file.

If you use Virtual Desktops or Spaces in macOS then you’ll notice that their arrangements often times change. This is because macOS by default sets to automatically rearrange Spaces by recent use. While this could be useful to some, it could get frustrating if it disrupts the flow of your work.

You can prevent this from happening and lock the arrangement by setting it up from Mission Control‘s preferences as the following;

1. Open System Preferences from the Apple menu.
   
2. Click on Mission Control.
   
3. Notice that Automatically rearrange Spaces based on most recent use is enabled.
   
4. Untick the checkbox for the option, and your Virtual Desktops / Spaces should no longer re-arrange by itself.
   

Google Chrome will offer to translate websites to English by automatically popping up the translate bar on non-English websites.

You’ll have the options to;

1. Always translate the particular language
2. Never translate the particular language
3. Never translate the particular site

You can completely disable this feature if that’s not your preference by following these steps;

1. Open Chrome‘s Setting page by going to chrome://settings from the URL bar.
   
2. Go to Advanced section at the end of the page.
   
3. Look for Languages and unfold the options .
   
4. Disable Offer to translate pages that aren't in a language you read at the bottom of the section.