.htaccess files

• Apache web server.
• .htaccess configuration files for Apache.
• Can have a different .htaccess file in each dir

• Apache allows an enormous amount of customisation of your web server.
• Apache docs
  • Apache Core Features

Example of .htaccess: How to stop caching

• Say you are editing CSS.
• To stop CSS ever being cached, put it in a CSS dir, and put a .htaccess file like this in that dir:

          <IfModule mod_expires.c>
                  ExpiresActive Off
          </IfModule>
          <IfModule mod_headers.c>
                  FileETag None
                  Header unset ETag
                  Header unset Pragma
                  Header unset Cache-Control
                  Header unset Last-Modified
                  Header set Pragma "no-cache"
                  Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"
                  Header set Expires "Thu, 1 Jan 1970 00:00:00 GMT"
          </IfModule>
  

• This tells the browser never to cache any file in that dir, but to always fetch the new version from the server.
• To see if it is working:
  On Chrome - DevTools - Network - Hard reload / Reload - see if it is coming from cache or not

Reference

• Caching in HTTP
• How to control cache on Apache

• Apache docs
  • Caching
  • Apache needs module mod_headers installed and enabled
  • CacheDisable

student.computing.dcu.ie

• The global Apache config file is:

   /etc/apache2/apache2.conf 

• User .htaccess can be turned off in apache2.conf using AllowOverride
• User .htaccess should currently be turned on.

Other examples of .htaccess

• ErrorDocument to redirect "404 not found" errors

• Options Indexes to block raw directory listings