How to redirect to www using .htaccess

                       Type your domain name without www in address bar. Check whether it redirects to your site or give a 301 error message. If you got 301 error message, then you will solve this problem using .htaccess.

Syntax:

              RewriteEngine On

              RewriteCond %(HTTP_HOST) ! ^www.domainname.com$ [NC]

              RewriteRule ^(.*)$ http://www.domainname.com/$1 [L, R=301]

Explanation:

              Where,

                          .htaccess force the all http requests to use either www.domainname.com or domainname.com .

                           HTTP_HOST - represents your domain name.

                           RewriteCond   - check the conditions if you typed domain name is not start with www, it 

redirect to next rewrite rule. 

                           ! ^www.domainname.com$ - means you typed domain name is not start with www.

                           NC - represents not case sensitive.

                           RewriteRule - means it redirect domain name without www to http://www.doaminname.com.

                           ^ - starting

                           .* - one or more characters.

                           $ - ending
                           L - if rule matches, don't process any other rewrite rules below this one.

                           R=302 - redirect code


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What is .htaccess

                       Hypertext  access is shortly called as htaccess. It is a directory level configuration file. Directory level means, where you locate your .htaccess file, it configure that directory only. Mostly, on server, it is placed on public_html folder for configure the files to access. You can control your site using it. It is supported by web servers.
   

Uses of .htaccess:

           - DirectoryIndex uses
           - used for restrict the user for access pages from website
           - redirect the urls
           - gives direction to server rather than search engine
           - create error document
           - compressing resources with gzip
           - add expires headers
           - enable and disable the additional functionality of apache webserver
           - prevent access to php.ini file
           - force scripts to display as a source code
           - ensure media files are downloaded instead of played
     

How to start with .htaccess?

   Syntax:
         <IfModule mod_rewrite.c>
             RewriteEngine On
             RewriteCond  %(REQUEST_FILENAME) !-f
             RewriteCond  %(REQUEST_FILENAME) !-d
             RewriteCond  %(REQUEST_FILENAME) !-l
             RewriteBase /
             DirectoryIndex index.php
             RewriteRule ^home index.php [L]
         </IfModule>
  Explanation:
     <IfModule mod_rewrite.c>
                                IfModule test whether mod_rewrite.c is included in apache. If mod_rewrite.c
is included, then it run. Otherwise it doesn't get run.
     RewriteEngine On
                                It tells apache to turn on its RewriteRules.
     RewriteCond
                                RewriteCond execute the next rewrite rules if it is correct.
%(REQUEST_FILENAME) is a variable based on url you request
!-f, !-d, !-l are extension added to regular expression.
where,
         !- f - rewrite condition if it is not  file
         !-d - rewrite condition if it is not directory
         !-l  - rewrite condition if it is not link
 if a file, taken from variable %(REQUEST_FILENAME) does not exist on the file system, then return true.
        RewriteBase /
                              It provide base for RewriteRules.                  
        DirectoryIndex index.php
                              It tells apache to which file is run first when server access to particular directory.
        RewriteRule
                              It redirect the urls.
RewriteRule ^home index.php [L]
      it means, when url get ' home ' on address bar, it runs the file index.php. Using this method, we can change our address bar contents to anything.
          For example,
                 RewriteRule ^sample.html sample.php [L]
                 where,
                            you type sample.html in your address bar, the .htaccess runs sample.php file.
  we can pass the values in address bar using it.
     
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