Directives
“Directives” is the terminology that Apache uses for the commands in Apache’s configuration files. They are normally relatively short commands, typically key value pairs, that modify Apache’s behavior. An .htaccess file allows developers to execute a bunch of these directives without requiring access to Apache’s core server configuration file, often named httpd.conf(httpd.conf typically referred to as the "global configuration file")Enabling .htaccess:
.htaccess files are normally enabled by default. This is actually controlled by the AllowOverride Directive in the httpd.conf file. This directive can only be placed inside of a <Directory> section. The typical httpd.conf file defines a DocumentRoot and the majority of the file will contain Directives inside a <Directory> section dealing with that directory. This includes the AllowOverride directive.The default value is actually “All” and thus .htaccess files are enabled by default. An alternative value would be “None” which would mean that they are completely disabled. There are numerous other values that limit configuration of only certain contexts.
Checking if .htaccess is Enabled:
1 - is_htaccess_enabledThis test case is very simple. It uses a directive to make Apache look first for the “indexgood.html” file before “index.html.” If .htaccess support is enabled, when you point your browser to the folder, Apache will load the .htaccess file and know that it should display the “indexgood.html” page
# This Directive will make Apache look first
# for "index_good.html" before looking for "index.html"
DirectoryIndex index_good.html index.html
2 - is_htaccess_enabled_2
Any syntax error in your .htaccess file will cause the server to hiccup.
You can use this to your advantage to test if your server has .htaccess support enabled!
# This file is intended to make Apache blow up. This will help
# determine if .htaccess is enabled or not!
AAAAAA
So, if you get back a page yelling
“Internal Server Error” then your server is looking for .htaccess files!
Consequences of .htaccess files:
- Always keep in mind that you’re affecting all of the subdirectories as well as the current directory.- Also, when enabled the server will take a potential performance hit. The reason is because, every server request, if .htaccess support is enabled, when Apache goes to fetch the requested file for the client, it has to look for a .htaccess file in every single directory leading up to wherever the file is stored.
Headers
Let's start simple, we'll add a header to the Response and see what happens:# Add the following header to every response
Header add X-HeaderName "Header Value"
I ran a test to check to see if certain modules were enabled on a web-server. I wrote the following check:
<IfModule mod_gzip.c>
Header add X-Enabled mod_gzip
</IfModule>
<IfModule mod_deflate.c>
Header add X-Enabled mod_deflate
</IfModule>
There is a difference between Header set and Header add. With add, the Header will always get added to the Response. Even if it happens to show up multiple times in the response. This is most often what you would want for custom headers. You would use set when you want to override the value of one of the default headers that Apache returns.
Custom error documents..
the usual method. the "err" folder (with the custom pages) is in the root# custom error documents
ErrorDocument 401 /err/401.php
ErrorDocument 403 /err/403.php
ErrorDocument 404 /err/404.php
ErrorDocument 500 /err/500.php
# quick custom error "document"..
ErrorDocument 404 "<html><head><title>NO!</title></head><body><h2><tt>There is nothing here.. go away quickly!</tt></h2></body></html>
Save bandwidth with .htaccess!
it enables PHP's built-in transparent zlib compression.<ifModule mod_php4.c>
php_value zlib.output_compression 16386
</ifModule>
Expire Header
<IfModule mod_expires.c>ExpiresActive on
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
</IfModule>
Compression by file extension
<IFModule mod_deflate.c>
<filesmatch "\.(js|css|html|jpg|png|php)$">
SetOutputFilter DEFLATE
</filesmatch>
</IFModule>
how to add the Vary Accept-Encoding header:
<IfModule mod_headers.c><FilesMatch "\.(js|css|xml|gz)$">
Header append Vary: Accept-Encoding
</FilesMatch>
</IfModule>
compression by file type
##################### GZIP COMPRESSION #
####################
SetOutputFilter DEFLATE
AddOutputFilterByType DEFLATE text/html text/css text/plain text/xml application/x-javascript application/x-httpd-php
BrowserMatch ^Mozilla/4 gzip-only-text/html
BrowserMatch ^Mozilla/4\.0[678] no-gzip
BrowserMatch \bMSIE !no-gzip !gzip-only-text/html
BrowserMatch \bMSI[E] !no-gzip !gzip-only-text/html
SetEnvIfNoCase Request_URI \.(?:gif|jpe?g|png)$ no-gzip
Header append Vary User-Agent env=!dont-vary
#End Gzip
Image Expire Tag
First we enable expirations and then we set a default expiry date for files we don't specify.<IfModule mod_expires.c>
# Enable expirations
ExpiresActive On
# Default directive
ExpiresDefault "access plus 1 month"
</IfModule>
# My favicon
ExpiresByType image/x-icon "access plus 1 year"
# Images
ExpiresByType image/gif "access plus 1 month"
ExpiresByType image/png "access plus 1 month"
ExpiresByType image/jpg "access plus 1 month"
ExpiresByType image/jpeg "access plus 1 month"
# CSS
ExpiresByType text/css "access plus 1 month"
# Javascript
ExpiresByType application/javascript "access plus 1 year"
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