How to change file/folder permissions in cPanel?

All files on UNIX (including Linux and other UNIX variants) machines have access permissions. In this way the operating system knows how to deal with requests to access the files. There are three types of access:

• Read - Denoted as r, files with read access can be displayed to the user
• Write - Denoted as w, files with write access can be modified by the user
• Execute - Denoted as x, files with execute access can be executed as programs bythe user

Access types are set for three types of user group:

• User - The owner of the file
• Group - Other files which are in the same folder or group
• World - Everyone else

How to redirect www URLs to non-www?

In order to redirect all requests for www.yourdomain.com to yourdomain.com, you should set the appropriate rewrite rule. This can be done by adding the following lines at the beginning of the .htaccess file in your public_html folder:
RewriteCond %{HTTP_HOST} ^www.yourdomain.com [NC]
RewriteRule ^(.*)$ http://yourdomain.com/$1 [L,R=301]
From now on, when someone accesses http://www.yourdomain.com she/he will be redirected to http://yourdomain.com.
Using this method is safe because it should not create any redirection loops nor it should interfere with other rewrite rules.