Here are some specific htaccess examples taken mostly from my WordPress Password Protection plugin, which does alot more than password protection as you will see from the following mod_rewrite examples. These are a few of the mod_rewrite uses that BlogSecurity declared pushed the boundaries of Mod_Rewrite! Some of these snippets are quite exotic and unlike anything you may have seen before, also only for those who understand them as they can kill a website pretty quick.

Directory Protection

Enable the DirectoryIndex Protection, preventing directory index listings and defaulting. [Disable]

Options -Indexes
DirectoryIndex index.html index.php /index.php

Password Protect wp-login.php

Requires a valid user/pass to access the login page[401]

<Files wp-login.php>
Order Deny,Allow
Deny from All
Satisfy Any
AuthName "Protected By AskApache"
AuthUserFile /home/askapache.com/.htpasswda1
AuthType Basic
Require valid-user
</Files>

Password Protect wp-admin

Requires a valid user/pass to access any non-static (css, js, images) file in this directory.[401]

Options -ExecCGI -Indexes +FollowSymLinks -Includes
DirectoryIndex index.php /index.php
Order Deny,Allow
Deny from All
Satisfy Any
AuthName "Protected By AskApache"
AuthUserFile /home/askapache.com/.htpasswda1
AuthType Basic
Require valid-user
<FilesMatch "\.(ico|pdf|flv|jpg|jpeg|mp3|mpg|mp4|mov|wav|wmv|png|gif|swf|css|js)$">
Allow from All
</FilesMatch>
<FilesMatch "(async-upload)\.php$">
<IfModule mod_security.c>
SecFilterEngine Off
</IfModule>
Allow from All
</FilesMatch>

Protect wp-content

Denies any Direct request for files ending in .php with a 403 Forbidden.. May break plugins/themes [401]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /wp-content/.*$ [NC]
RewriteCond %{REQUEST_FILENAME} !^.+flexible-upload-wp25js.php$
RewriteCond %{REQUEST_FILENAME} ^.+\.(php|html|htm|txt)$
RewriteRule .* - [F,NS,L]

Protect wp-includes

Denies any Direct request for files ending in .php with a 403 Forbidden.. May break plugins/themes [403]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /wp-includes/.*$ [NC]
RewriteCond %{THE_REQUEST} !^[A-Z]{3,9}\ /wp-includes/js/.+/.+\ HTTP/ [NC]
RewriteCond %{REQUEST_FILENAME} ^.+\.php$
RewriteRule .* - [F,NS,L]

Common Exploits

Block common exploit requests with 403 Forbidden. These can help alot, may break some plugins. [403]

RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ ///.*\ HTTP/ [NC,OR]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*\?\=?(http|ftp|ssl|https):/.*\ HTTP/ [NC,OR]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*\?\?.*\ HTTP/ [NC,OR]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*\.(asp|ini|dll).*\ HTTP/ [NC,OR]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*\.(htpasswd|htaccess|aahtpasswd).*\ HTTP/ [NC]
RewriteRule .* - [F,NS,L]

Stop Hotlinking

Denies any request for static files (images, css, etc) if referrer is not local site or empty. [403]

RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteCond %{HTTP_REFERER} !^http://www.askapache.com.*$ [NC]
RewriteRule \.(ico|pdf|flv|jpg|jpeg|mp3|mpg|mp4|mov|wav|wmv|png|gif|swf|css|js)$ - [F,NS,L]

Safe Request Methods

Denies any request not using GET,PROPFIND,POST,OPTIONS,PUT,HEAD[403]

RewriteCond %{REQUEST_METHOD} !^(GET|HEAD|POST|PROPFIND|OPTIONS|PUT)$ [NC]
RewriteRule .* - [F,NS,L]

Forbid Proxies

Denies any POST Request using a Proxy Server. Can still access site, but not comment. See Perishable Press [403]

RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{HTTP:VIA}%{HTTP:FORWARDED}%{HTTP:USERAGENT_VIA}%{HTTP:X_FORWARDED_FOR}%{HTTP:PROXY_CONNECTION} !^$ [OR]
RewriteCond %{HTTP:XPROXY_CONNECTION}%{HTTP:HTTP_PC_REMOTE_ADDR}%{HTTP:HTTP_CLIENT_IP} !^$
RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteRule .* - [F,NS,L]

Real wp-comments-post.php

Denies any POST attempt made to a non-existing wp-comments-post.php[403]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*/wp-comments-post\.php.*\ HTTP/ [NC]
RewriteRule .* - [F,NS,L]

HTTP PROTOCOL

Denies any badly formed HTTP PROTOCOL in the request, 0.9, 1.0, and 1.1 only[403]

RewriteCond %{THE_REQUEST} !^[A-Z]{3,9}\ .+\ HTTP/(0\.9|1\.0|1\.1) [NC]
RewriteRule .* - [F,NS,L]

SPECIFY CHARACTERS

Denies any request for a url containing characters other than "a-zA-Z0-9.+/-?=&" - REALLY helps but may break your site depending on your links. [403]

RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteCond %{THE_REQUEST} !^[A-Z]{3,9}\ [a-zA-Z0-9\.\+_/\-\?\=\&]+\ HTTP/ [NC]
RewriteRule .* - [F,NS,L]

BAD Content Length

Denies any POST request that doesnt have a Content-Length Header[403]

RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{HTTP:Content-Length} ^$
RewriteCond %{REQUEST_URI} !^/(wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteRule .* - [F,NS,L]

BAD Content Type

Denies any POST request with a content type other than application/x-www-form-urlencoded|multipart/form-data[403]

RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{HTTP:Content-Type} !^(application/x-www-form-urlencoded|multipart/form-data.*(boundary.*)?)$ [NC]
RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteRule .* - [F,NS,L]

Missing HTTP_HOST

Denies requests that dont contain a HTTP HOST Header.[403]

RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteCond %{HTTP_HOST} ^$
RewriteRule .* - [F,NS,L]

Bogus Graphics Exploit

Denies obvious exploit using bogus graphics[403]

RewriteCond %{HTTP:Content-Disposition} \.php [NC]
RewriteCond %{HTTP:Content-Type} image/.+ [NC]
RewriteRule .* - [F,NS,L]

No UserAgent, Not POST

Denies POST requests by blank user-agents. May prevent a small number of visitors from POSTING. [403]

RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{HTTP_USER_AGENT} ^-?$
RewriteCond %{REQUEST_URI} !^/(wp-login.php|wp-admin/|wp-content/plugins/|wp-includes/).* [NC]
RewriteRule .* - [F,NS,L]

No Referer, No Comment

Denies any comment attempt with a blank HTTP_REFERER field, highly indicative of spam. May prevent some visitors from POSTING. [403]

RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.*/wp-comments-post\.php.*\ HTTP/ [NC]
RewriteCond %{HTTP_REFERER} ^-?$
RewriteRule .* - [F,NS,L]

Trackback Spam

Denies obvious trackback spam. See Holy Shmoly! [403]

RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{HTTP_USER_AGENT} ^.*(opera|mozilla|firefox|msie|safari).*$ [NC]
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /.+/trackback/?\ HTTP/ [NC]
RewriteRule .* - [F,NS,L]

Map all URIs except those corresponding to existing files to a handler

RewriteEngine On
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-d
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} !-f
RewriteRule . /script.php

Map any request to a handler

In the case where all URIs should be sent to the same place (including potentially requests for static content) the method to use depends on the type of the handler. For php scripts, use: For other handlers such as php scripts, use:

RewriteEngine On
RewriteCond %{REQUEST_URI} !=/script.php
RewriteRule .* /script.php

And for CGI scripts:

ScriptAliasMatch .* /var/www/script.cgi

Map URIs corresponding to existing files to a handler instead

RewriteEngine On
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -d [OR]
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -f
RewriteCond %{REQUEST_URI} !=/script.php
RewriteRule .* /script.php

If the existing files you wish to have handled by your script have a common set of file extensions distinct from that of the hander, you can bypass mod_rewrite and use instead mod_actions. Let's say you want all .html and .tpl files to be dealt with by your script:

Action foo-action /script.php
AddHandler foo-action html tpl

Deny access if var=val contains the string foo.

RewriteCond %{QUERY_STRING} foo
RewriteRule ^/url - [F]

Removing the Query String

RewriteRule ^/url /url?

Adding to the Query String

Keep the existing query string using the Query String Append flag, but add var=val to the end.

RewriteRule ^/url /url?var=val [QSA]

Rewriting For Certain Query Strings

Rewrite URLs like http://askapache.com/url1?var=val to http://askapache.com/url2?var=val but don't rewrite if val isn't present.

RewriteCond %{QUERY_STRING} val
RewriteRule ^/url1 /url2

Modifying the Query String

Change any single instance of val in the query string to other_val when accessing /path. Note that %1 and %2 are back-references to the matched part of the regular expression in the previous RewriteCond.

RewriteCond %{QUERY_STRING} ^(.*)val(.*)$
RewriteRule /path /path?%1other_val%2

Mod_Rewrite Security originally appeared on AskApache.com

This is part 2 of the exhaustive Htaccess Tutorial. I realized it was so lengthy that search engines and visitors were having real problems with it, so I moved half of it here. But this gave me the opportunity to add a ton of new stuff that I hadn't been able to add to the main htaccess tutorial. And now this new part 2 is already twice as big as the original! To sum up, this is a work in progress.

Moving Half of Original Tutorial to a new URL - SEO Rewriting

Well, the original tutorial was at /htaccess/apache-htaccess.html, but it was such a huge article that search engines were dropping it! So I split it into 3 new urls.

1. /htaccess/htaccess.html - 1
2. /htaccess/htaccess-rewrites.html - Rewrites
3. /htaccess/apache-htaccess-2.html - Part 2

The /htaccess/apache-htaccess-2.html is a lot of unfinished new stuff, and the /htaccess/htaccess-rewrites.html (this very page) still needs to be split several times to get the filesize down.

301 Link Juice

The /apache-htaccess.html url has been around since 2006, and it was full of original ideas and examples for using htaccess. Almost every htaccess guide or tutorial published since then has many of the examples and ideas from that tutorial, (I encourage people to modify and republish everything on this site according to copyright). I know it, the authors sometimes know it, but the main point is Google for sure knows it. That's the beauty of creating unique content, Google sees that. So that /apache-htaccess.html link has extreme link juice, from all the sites, books, papers, and presentations that have linked to it since 2006.

Filesize Is important

I like to use my blog as a way to keep notes about my research organized, and I am extremely good at doing research, unfortunately, that means I have a huge article. The filesize for the html alone is larger than all the other resources like javascript and images, combined.

• So that means it is very difficult to view on a mobile device, or a slow connection.
• For google-bot and other search engine crawlers and robots, this is a huge problem (I made a big mistake letting it get that size).
• The robot has to parse an enormous single html file, containing hundreds/thousands of external and internal links, and its such an issue they can decide to just skip indexing that url until the filesize is manageable.
• Once again, it's all about the human experience, a huge single file is not good for anyone who isn't printing it out to read offline.

Starting Fresh without losing juice

So since the page wasn't being indexed much since it was so huge, I decided to split up the content into new separate urls and utilize a 301 Redirect to transfer all the link juice from /apache-htaccess.html to /htaccess.html.

301 Redirect Timeline

1. Now, the idea is to take the first pages from the original multi-page guide, do a little improvement on that content, and save it to the new url /htaccess.html.
2. Then just continue taking the next page from the remaining original guide and creating new pages using the original links structure. /apache-htaccess-2.html, /apache-htaccess-3.html, etc.. This is a secondary backup to the new /htaccess.html url, which will receive the 301 link juice from the old url, but these secondary pages will help keep the links on external sites good.
3. Then, I setup a 301 Redirect in my .htaccess file to redirect the old url to the new /htaccess.html url.
4. Finally, I delete the old url and it is replaced forever by a 301 Redirect pointing to my new location, filesize problems eliminated.

301 Redirect Code Used

This is so easy to do with RedirectMatch, way faster and easier than using mod_rewrite to handle this, and much less overhead. Note that this is a general command that I will leave up for a few weeks and slowly tighten it up by looking at my Google Analytics and Apache Logs. For instance, this first redirectmatch rule is an older RedirectMatch I still have active to redirect all the old links pointing at /2006/htaccess/apache-htaccess.html to /htaccess/apache-htaccess.html from when I ditched the date-based permalinks back in 2007, and you can see it is a little tighter than the 2nd one which also redirects requests for apache-htaccess.html/feed/ or trackback or whatever.

RedirectMatch 301 ^/2006/.*apache-htaccess.html$ http://www.askapache.com/htaccess/apache-htaccess.html
RedirectMatch 301 ^/.*apache-htaccess.html(.*)$ http://www.askapache.com/htaccess/htaccess.html$1

Advanced 301 Redirects for SEO

I wrote a couple of articles that go into detail about maximizing the SEO with linking and redirects, it remains one of my most helpful articles to anyone trying to rank higher the right way, the Google way.. SEO Secrets of AskApache Part 2

Htaccess Rewrites for Moving Urls originally appeared on AskApache.com

The idea is to have the browser display programming and code similar to the high-quality found on a developers machine, like this older screenshot of my vim.

The most important step is to figure out the font-family and the basic font-attributes. You want to show the best font for those visitors (like me) who have all these extra console fonts, but fallback to a font that anyone in the world can view.

Monospace is the fallback

15.3.1.5 monospace

The sole criterion of a monospace font is that all glyphs have the same fixed width. (This can make some scripts, such as Arabic, look most peculiar.) The effect is similar to a manual typewriter, and is often used to set samples of computer code.

CSS Rules for Code

Here are a few css rules I use. That is my ultimate font-family heirarchy of console-type fonts, though not many people have them installed. The fallback is usually Andale Mono, Monaco, or DejaVu Sans Mono, Lucida Console, Bitstream, then Courier.

kbd, samp, tt, pre, code, var,
.code, .pre {
   font-family: Terminus,Consolas,Profont,"Andale Mono",Monaco,Inconsolata,Inconsolata-g,
      Unifont,Lime,"ClearlyU PUA",Clean,"DejaVu Sans Mono","Lucida Console",
      "Bitstream Vera Sans Mono",Freemono,"Liberation Mono",Dina,Anka,Droid Sans Mono,
      Anonymous Pro,Proggy fonts,Envy Code R,Gamow,Courier,"Courier New",Terminal,monospace;
}

This is just some basic pre attributes, useful as a reset or to force the issue. You may just want to do .pre {...} to apply to elements with class="pre" instead of applying to all pre elements sitewide.

pre { letter-spacing:normal; word-spacing:normal; text-transform:none; max-width:100%; overflow:auto; white-space:pre-wrap; }
pre.normal { white-space:normal }

Live Font Examples

What you see is what you get, so experiment with different browsers.

• Courier
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Courier New
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Terminal
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Agency FB Bold
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Consolas
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Terminus
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Profont
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Andale Mono
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Monaco
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Inconsolata
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Inconsolata-g
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Unifont
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Lime
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• ClearlyU PUA
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Clean
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• DejaVu Sans Mono
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Lucida Console
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Bitstream Vera Sans Mono
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Freemono
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Liberation Mono
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Dina
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Anka
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Droid Sans Mono
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Anonymous Pro
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Proggy fonts
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Envy-Code-R
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

• Gamow
  

  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  | 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 |
  |     Type      |      Code     |          A B C D E F G H      |

More Info and Software

• CSS Font Families Example at W3
• Monospace/Fixed Width Programmer's Fonts
• WinFontsView v1.10 - View samples of Windows fonts installed on your system

Programming Fonts for the Web originally appeared on AskApache.com

FYI, using the Mod_Rewrite Variables Cheatsheet makes this example, and all advanced .htaccess code easier to understand. This demo lets you set a cookie with 1 of 3 values, then you just request the pdf file with a normal link click and get 1 of 3 different responses. This is accomplished with a nice bit of .htaccess code.

As I explain the htaccess code that achieves this, keep in mind this is merely one simple application for this code. It's much more advanced than your basic htaccess trick, notice how this htaccess acts like a php script, very unusual.. I really wanted to share this trick after I created it for one of my clients because this is the tip of the iceberg. Another use would be to display an alternate style sheet depending on a users theme preference. The coolest thing is that it uses multiple advanced .htaccess ideas. This code uses mod_headers to set the Content-Disposition header for forcing a download and uses mod_rewrite to: Send different Content-Type headers, Check the value of a cookie, Set environment variables for use later by mod_headers header directive

What's Going On

There are 3 different ways for a server to send a pdf file in response to a request for one. This causes 3 different ways to open/view the pdf file in the clients browser.

1. The browser display's a "Save File As" dialog, allowing you to save the file or open.
2. The browser opens the pdf file "Inline", opening the pdf file in the browser like a web page.
3. The browser "Downloads" the pdf file automatically as an "Attachment" and then causes an external pdf reader program like adobe reader to open the file.

Some people prefer to have the option of saving the file to view later, some prefer opening it with an external program, and some just like the pdf file to load right in the browser... The point is that by using .htaccess, we can let them choose any of the 3 methods and save their preference for all further pdf files requested from our site by that user.

How It Works

When you click on one of the 3 demo buttons above, "Inline", "Save As", or "Download", a cookie named askapache_pdf is saved in your browser using the javascript below, with the value being set to which button you clicked. Then when you request the pdf file the .htaccess code below uses mod_rewrite to read the value of the askapache_pdf cookie, and depending on which was your preference it will send alternate HTTP Headers that control how your browser handles the file.

Unique HTTP Headers Returned

When it comes down to it, the following information is the 3 modes. Notice each one is different, because these headers are the only thing controlling how your browser handles the file.

Save As Mode (askapache_pdf=s)

Content-Disposition: attachment
Content-Type: application/pdf

Inline Mode (askapache_pdf=i)

Content-Type: application/pdf

Download Mode (askapache_pdf=a)

Content-Type: application/octet-stream

Htaccess Demo File

For the demo I created the folder /storage/pdf/ and this is the .htaccess file at /storage/pdf/.htaccess

The default Content-Type for .pdf files. This will make .pdf files default Content-Type header have the value 'application/pdf' - but the default can be overridden by using RewriteRule with the [T='different/type']

AddType application/pdf .pdf

Turn on the rewrite engine if its already on you dont need this

RewriteEngine On

Skip RewriteRules if not .pdf request, like autoindexing. The next [2] RewriteRule directives are specific for .pdf files so if the filename requested does not end in .pdf then the [S=2] instructs the next 2 RewriteRule directives to be completely skipped.

RewriteRule !.*\.pdf$ - [S=2]

The first RewriteCond checks to see if the askapache_pdf cookie is NOT set. The second RewriteCond checks to see if the askapche_pdf cookie has the value of s, which is the value corresponding to someone clicking the "Save As" button.

The [NC,OR] flag means that if the cookie askapache_pdf does not exist, OR (next cond) if the askapache_pdf cookie does exist and is set to 's' then process the RewriteRule. If neither cond is true the rewriterule is skipped.

If one of the RewriteCond is true, then the RewriteRule is processed. The RewriteRule applies to any/all requests (.*) but doesn't rewrite anything (-) This RewriteRule sets an Apache environment variable ASKAPACHE_PDFS to have the value of 1 if either rewritecond is true. The variable can be checked by any directives following the rewriterule in the whole htaccess file. The ASKAPACHE_PDFS ends in S because if this variable exists then it means the users preference is 'Save As'

Notice that if the user requested the pdf file without selecting a preference i.e. no cookie exists, then the ASKAPACHE_PDFS variable is still set. This just lets us pick the default preference for them, in this example the default is 'Save As'

RewriteCond %{HTTP_COOKIE} !^.*askapache_pdf.*$ [NC,OR]
RewriteCond %{HTTP_COOKIE} ^.*askapache_pdf=s.*$ [NC]
RewriteRule .* - [E=ASKAPACHE_PDFS:1]

The RewriteCond checks the askapache_pdf cookie for the value 'a' which 'a' represents 'Download'

If the cookies value is 'a' then the RewriteRule overrides the default Content-Type from 'application/pdf' set with AddType earlier, to 'application/octet-stream', which is a special content-type that tells the browser that the file cannot be loaded by the browser 'Inline', but must be saved which will be opened by an external viewer depending on browser configuration and plugins.

RewriteCond %{HTTP_COOKIE} ^.*askapache_pdf=a.*$
RewriteRule .* - [T=application/octet-stream]

This is superfly. If the cookie/users-preference was 'Save As' (s) then the RewriteRule above the last one set the environment variable ASKAPACHE_PDFS to have the value 1. The Header directive here is ONLY processed in that variable ASKAPACHE_PDFS exists. That is what the end 'env=ASKAPACHE_PDFS' does, it is the condition that must be met or the Header directive is skipped. If the ASKAPACHE_PDFS environment variable set by RewriteRule does exist then the header directive adds the header 'Content-Disposition: attachment' to the normal Response Headers. The 'Content-Disposition: attachment' header instructs your browser to present you with the 'Save As' dialog box allowing you to choose whether you want to save or open.

Header set Content-Disposition "attachment" env=ASKAPACHE_PDFS

Javascript used by Demo

The best place for javascript is quirksmode, here is a definitive article on setting, reading, parsing, etc.. COOKIES.

Note, I now prefer using jQuery over my AAJS javascript library. Also, the whole using cookies aspect is just to highlight some advanced htaccess, you can accomplish this much easier without javascript or cookies.

if(!gi('pdfr'))return;
var pdfr=gi('pdfr');
var cval=getCookie('askapache_pdf');
 
if(cval=='i'){pdfr.innerHTML='Currently set to "Inline".';}
else if(cval=='a'){pdfr.innerHTML='Currently set to "Download" mode.';}
else if(cval=='s'){pdfr.innerHTML='Currently set to "Save As" mode.';}
 
addMyEvent(gi('pdfi'),"mousedown",function(){
  setCookie("askapache_pdf", "i", "", "/", "www.askapache.com"); gi('pdfr').innerHTML = 'Changed mode to "Inline".'; return false; });
addMyEvent(gi('pdfa'),"mousedown",function(){
  setCookie("askapache_pdf", "a", "", "/", "www.askapache.com"); gi('pdfr').innerHTML = 'Changed mode to "Download".'; return false; });
addMyEvent(gi('pdfs'),"mousedown",function(){
  setCookie("askapache_pdf", "s", "", "/", "www.askapache.com"); gi('pdfr').innerHTML = 'Changed mode to "Save As".'; return false; });

Alternative Method - No Cookies + PHP

This is what I came up with first for my client, and then while programming the php I noticed.. Hey! I think I can do the same thing using .htaccess, which would save me on cpu/memory/potential security/etc.. but this works great too. Though you will need to hack the code to get it working probably..

Note that the .htaccess rewrite code I used here used FILENAME-i.pdf or FILENAME-s.pdf to pass the preference to the pdf-dl.php script, it also worked for FILENAME.pdf?i=i

pdf-dl.php

<?php
if (
  !isset($_GET['file'])
  || ($f=$_GET['file'])===false
  || ($fp=@fopen($f,"rb"))===false
  || ($fi=pathinfo($f))===false
  || ($fi['fsize']=filesize($f))===false
  || strtolower($fi["extension"])!='pdf'
) die('Failed');
 
ob_start();
header('Accept-Ranges: bytes');
header("Content-Length: {$fi['fsize']}");
header('Content-Type: application/pdf');
if(!isset($_GET['i'])) header("Content-Disposition: attachment; filename=\"{$fi['basename']}\"");
 
$sent = 0;
while ( !feof($fp) && $sent < $fi['fsize'] && ($buf = fread($fp, 8192)) != '' ){
  echo $buf;
  $sent += strlen($buf);
  flush();  ob_flush();
}
fclose($fp);
exit;
?>

Alternate Method .htaccess

Deny direct request to pdf-dl.php file

RewriteCond %{THE_REQUEST} ^.*pdf-dl\.php.*$ [NC]
RewriteRule .* - [F]

Handle PDF files named anything-i.pdf as inline

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ([^/]*)-i\.pdf$  /cgi-bin/pdf-dl.php?i=i&file=%{DOCUMENT_ROOT}/storage/pdf/$1.pdf [L,NC,QSA,S=1]

Handle PDF files without -i.pdf as attachments

RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ([^/]*)\.pdf$  /cgi-bin/pdf-dl.php?file=%{DOCUMENT_ROOT}/storage/pdf/$1.pdf [L,NC,QSA]

More Info

The following is more information about the Content-Dispositon header and related subjects for fast readers.

Interesting Reading

Here is the thread of the original draft proposal for the Content-Disposition header.

• Content-Disposition Header, Rens Troost - 22 Jun 1993
  • Re: Content-Disposition Header, Nathaniel Borenstein
    • Re: Content-Disposition Header, Gabe Beged-Dov
      • Re: Content-Disposition Header, Rens Troost
      • Re: Content-Disposition Header, Gabe Beged-Dov
      • Content-Disposition Header and multipart/alternative, Rens Troost
      • Re: Content-Disposition Header and multipart/alternative, Nathaniel Borenstein
    • Re: Content-Disposition Header, Keith Moore
      • Re: Content-Disposition Header, Nathaniel Borenstein
      • Re: Content-Disposition Header, Ed Levinson (Contractor)
      • Re: Content-Disposition Header, Keith Moore
      • Re: Content-Disposition Header, Rens Troost
      • Re: Content-Disposition Header, Harald Tveit Alvestrand
    • Re: Content-Disposition Header, Steve Dorner
      • Re: Content-Disposition Header, Rens Troost
        • Re: Content-Disposition Header, Keith Moore
    • Re: Content-Disposition Header, Carlyn M. Lowery

Intense Reading

• Using the MIME Headers Effectively
• Mail Content Disposition Values and Parameters
• Tags for the Identification of Languages
• The Internet Gopher Protocol (a distributed document search and retrieval protocol)
• Universal Resource Identifiers in WWW
• Uniform Resource Locators (URL)
• Hypertext Markup Language - 2.0
• Hypertext Transfer Protocol -- HTTP/1.0
• Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies
• Requirements for Internet Hosts -- Communication Layers
• Standard for The Format of ARPA Internet Text Messages
• Relative Uniform Resource Locators
• Standard for Interchange of USENET Messages
• Network News Transfer Protocol
• MIME (Multipurpose Internet Mail Extensions) Part Three: Message Header Extensions for Non-ASCII Text
• Form-based File Upload in HTML
• Simple Mail Transfer Protocol
• Media Type Registration Procedure
• File Transfer Protocol
• Assigned Numbers
• Functional Requirements for Uniform Resource Names
• The Content-MD5 Header Field
• Renumbering Needs Work
• GZIP file format specification version 4.3
• Improving HTTP Latency
• Analysis of HTTP Performance
• Network Time Protocol (Version 3) Specification, Implementation and Analysis
• DEFLATE Compressed Data Format Specification version 1.3
• Analysis of HTTP Performance Problems,
• ZLIB Compressed Data Format Specification version 3.3
• An Extension to HTTP: Digest Access Authentication
• Hypertext Transfer Protocol -- HTTP/1.1
• Key words for use in RFCs to Indicate Requirement Levels
• Communicating Presentation Information in Internet Messages: The Content-Disposition Header
• Use and Interpretation of HTTP Version Numbers
• Common Internet Message Headers
• UTF-8, a transformation format of Unicode and ISO-10646
• Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types
• IETF Policy on Character Sets and Languages
• Uniform Resource Identifiers (URI): Generic Syntax and Semantics
• HTTP Authentication: Basic and Digest Access Authentication
• MIME E-mail Encapsulation of Aggregate Documents, such as HTML (MHTML)
• The Internet Standards Process -- Revision 3
• Hyper Text Coffee Pot Control Protocol (HTCPCP/1.0)
• Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples
• Communicating Presentation Information in Internet Messages: The Content-Disposition Header Field

3 Ways to Serve PDF Files using Htaccess Cookies, Headers, Rewrites originally appeared on AskApache.com

Htaccess Rewrites are enabled by using the Apache module mod_rewrite, which is one of the most powerful Apache modules and features availale. Htaccess Rewrites through mod_rewrite provide the special ability to Rewrite requests internally as well as Redirect request externally.

When the url in your browser's location bar stays the same for a request it is an internal rewrite, when the url changes an external redirection is taking place. This is one of the first, and one of the biggest mental-blocks people have when learning about mod_rewrite... But I have a secret weapon for you to use, a new discovery from years of research that makes learning mod_rewrite drastically quicker and easier. It truly does or I wouldn't be saying so in the introduction of this article.

Despite the tons of examples and docs, mod_rewrite is voodoo. Damned cool voodoo, but still voodoo.
-- Brian Moore

Note: After years of fighting to learn my way through rewriting urls with mod_rewrite, I finally had a breakthrough and found a way to outsmart the difficulty of mod_rewrite that I just couldn't seem to master. The Mod_Rewrite RewriteCond/RewriteRule Variable Value Cheatsheet is the one-of-a-kind tool that changed the game for me and made mod_rewriting no-harder than anything else.

So keep that mod_rewrite reference bookmarked and you will be able to figure out any RewriteRule or RewriteCond, an amazing feat considering it took me a LONG time to figure this stuff out on my own. But that was before the craziness, one of the most challenging and productive .htaccess experiments I've done... An experiment so ILL it's sick like a diamond disease on your wrist! $$$. That mod_rewrite experiment/tutorial was the culmination of many different advanced mod_rewrite experiments I had done in the past and included most of my very best .htaccess tricks. With the cheatsheet it's no longer Voodoo.. Its just what you do. Now lets dig in!

If you really want to take a look, check out the mod_rewrite.c and mod_rewrite.h files.

Be aware that mod_rewrite (RewriteRule, RewriteBase, and RewriteCond) code is executed for each and every HTTP request that accesses a file in or below the directory where the code resides, so it's always good to limit the code to certain circumstances if readily identifiable.

For example, to limit the next 5 RewriteRules to only be applied to .html and .php files, you can use the following code, which tests if the url does not end in .html or .php and if it doesn't, it will skip the next 5 RewriteRules.

RewriteRule !\.(html|php)$ - [S=5]
RewriteRule ^.*-(vf12|vf13|vf5|vf35|vf1|vf10|vf33|vf8).+$ - [S=1]

.htaccess rewrite examples should begin with:

Options +FollowSymLinks
 
RewriteEngine On
RewriteBase /

Require the www

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !^www\.askapache\.com$ [NC]
RewriteRule ^(.*)$ http://www.askapache.com/$1 [R=301,L]

Loop Stopping Code

Sometimes your rewrites cause infinite loops, stop it with one of these rewrite code snippets.

RewriteCond %{REQUEST_URI} ^/(stats/|missing\.html|failed_auth\.html|error/).* [NC]
RewriteRule .* - [L]
 
RewriteCond %{ENV:REDIRECT_STATUS} 200
RewriteRule .* - [L]

Cache-Friendly File Names

This is probably my favorite, and I use it on every site I work on. It allows me to update my javascript and css files in my visitors cache's simply by naming them differently in the html, on the server they stay the same name. This rewrites all files for /zap/j/anything-anynumber.js to /zap/j/anything.js and /zap/c/anything-anynumber.css to /zap/c/anything.css

RewriteRule ^zap/(j|c)/([a-z]+)-([0-9]+)\.(js|css)$ /zap/$1/$2.$4 [L]

SEO friendly link for non-flash browsers

When you use flash on your site and you properly supply a link to download flash that shows up for non-flash aware browsers, it is nice to use a shortcut to keep your code clean and your external links to a minimum. This code allows me to link to site.com/getflash/ for non-flash aware browsers.

RewriteRule ^getflash/?$ http://www.adobe.com/shockwave/download/download.cgi?P1_Prod_Version=ShockwaveFlash [NC,L,R=307]

Removing the Query_String

On many sites, the page will be displayed for both page.html and page.html?anything=anything, which hurts your SEO with duplicate content. An easy way to fix this issue is to redirect external requests containing a query string to the same uri without the query_string.

RewriteCond %{THE_REQUEST} ^GET\ /.*\;.*\ HTTP/
RewriteCond %{QUERY_STRING} !^$
RewriteRule .* http://www.askapache.com%{REQUEST_URI}? [R=301,L]

Sending requests to a php script

This .htaccess rewrite example invisibly rewrites requests for all Adobe pdf files to be handled by /cgi-bin/pdf-script.php

RewriteRule ^(.+)\.pdf$  /cgi-bin/pdf-script.php?file=$1.pdf [L,NC,QSA]

Setting the language variable based on Client

For sites using multiviews or with multiple language capabilities, it is nice to be able to send the correct language automatically based on the clients preferred language.

RewriteCond %{HTTP:Accept-Language} ^.*(de|es|fr|it|ja|ru|en).*$ [NC]
RewriteRule ^(.*)$ - [env=prefer-language:%1]

Deny Access To Everyone Except PHP fopen

This allows access to all files by php fopen, but denies anyone else.

RewriteEngine On
RewriteBase /
RewriteCond %{THE_REQUEST} ^.+$ [NC]
RewriteRule .* - [F,L]

If you are looking for ways to block or deny specific requests/visitors, then you should definately read Blacklist with mod_rewrite. I give it a 10/10

Deny access to anything in a subfolder except php fopen

This can be very handy if you want to serve media files or special downloads but only through a php proxy script.

RewriteEngine On
RewriteBase /
RewriteCond %{THE_REQUEST} ^[A-Z]{3,9}\ /([^/]+)/.*\ HTTP [NC]
RewriteRule .* - [F,L]

Require no www

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !^askapache\.com$ [NC]
RewriteRule ^(.*)$ http://askapache.com/$1 [R=301,L]

Check for a key in QUERY_STRING

Uses a RewriteCond Directive to check QUERY_STRING for passkey, if it doesn't find it it redirects all requests for anything in the /logged-in/ directory to the /login.php script.

RewriteEngine On
RewriteBase /
RewriteCond %{QUERY_STRING} !passkey
RewriteRule ^/logged-in/(.*)$ /login.php [L]

Removes the QUERY_STRING from the URL

If the QUERY_STRING has any value at all besides blank than the?at the end of /login.php? tells mod_rewrite to remove the QUERY_STRING from login.php and redirect.

RewriteEngine On
RewriteBase /
RewriteCond %{QUERY_STRING} .
RewriteRule ^login.php /login.php? [L]

Fix for infinite loops

An error message related to this isRequest exceeded the limit of 10 internal redirects due to probable configuration error. Use 'LimitInternalRecursion' to increase the limit if necessary. Use 'LogLevel debug' to get a backtrace.or you may seeRequest exceeded the limit,probable configuration error,Use 'LogLevel debug' to get a backtrace, orUse 'LimitInternalRecursion' to increase the limit if necessary

RewriteCond %{ENV:REDIRECT_STATUS} 200
RewriteRule .* - [L]

External Redirect .php files to .html files (SEO friendly)

RewriteRule ^(.*)\.php$ /$1.html [R=301,L]

Internal Redirect .php files to .html files (SEO friendly)

Redirects all files that end in .html to be served from filename.php so it looks like all your pages are .html but really they are .php

RewriteRule ^(.*)\.html$ $1.php [R=301,L]

block access to files during certain hours of the day

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
# If the hour is 16 (4 PM) Then deny all access
RewriteCond %{TIME_HOUR} ^16$
RewriteRule ^.*$ - [F,L]

Rewrite underscores to hyphens for SEO URL

Converts all underscores "_" in urls to hyphens "-" for SEO benefits... See the full article for more info.

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
 
RewriteRule !\.(html|php)$ - [S=4]
RewriteRule ^([^_]*)_([^_]*)_([^_]*)_([^_]*)_(.*)$ $1-$2-$3-$4-$5 [E=uscor:Yes]
RewriteRule ^([^_]*)_([^_]*)_([^_]*)_(.*)$ $1-$2-$3-$4 [E=uscor:Yes]
RewriteRule ^([^_]*)_([^_]*)_(.*)$ $1-$2-$3 [E=uscor:Yes]
RewriteRule ^([^_]*)_(.*)$ $1-$2 [E=uscor:Yes]
 
RewriteCond %{ENV:uscor} ^Yes$
RewriteRule (.*) http://d.com/$1 [R=301,L]

Require the www without hardcoding

Options +FollowSymLinks
RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} !^www\.[a-z-]+\.[a-z]{2,6} [NC]
RewriteCond %{HTTP_HOST} ([a-z-]+\.[a-z]{2,6})$     [NC]
RewriteRule ^/(.*)$ http://%1/$1 [R=301,L]

Require no subdomain

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} \.([a-z-]+\.[a-z]{2,6})$ [NC]
RewriteRule ^/(.*)$ http://%1/$1 [R=301,L]

Require no subdomain

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_HOST} \.([^\.]+\.[^\.0-9]+)$
RewriteRule ^(.*)$ http://%1/$1 [R=301,L]

Redirecting WordPress Feeds to Feedburner

Full article:Redirecting WordPress Feeds to Feedburner

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_URI} ^/feed\.gif$
RewriteRule .* - [L]
 
RewriteCond %{HTTP_USER_AGENT} !^.*(FeedBurner|FeedValidator) [NC]
RewriteRule ^feed/?.*$ http://feeds.feedburner.com/apache/htaccess [L,R=302]
 
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]

Only allow GET and PUT Request Methods

Article: Request Methods

RewriteEngine On
RewriteBase /
RewriteCond %{REQUEST_METHOD} !^(GET|PUT)
RewriteRule .* - [F]

Prevent Files image/file hotlinking and bandwidth stealing

RewriteEngine On
RewriteBase /
RewriteCond %{HTTP_REFERER} !^$
RewriteCond %{HTTP_REFERER} !^http://(www\.)?askapache.com/.*$ [NC]
RewriteRule \.(gif|jpg|swf|flv|png)$ /feed/ [R=302,L]

Stop browser prefetching

RewriteEngine On
SetEnvIfNoCase X-Forwarded-For .+ proxy=yes
SetEnvIfNoCase X-moz prefetch no_access=yes
 
# block pre-fetch requests with X-moz headers
RewriteCond %{ENV:no_access} yes
RewriteRule .* - [F,L]

This module uses a rule-based rewriting engine (based on a regular-expression parser) to rewrite requested URLs on the fly. It supports an unlimited number of rules and an unlimited number of attached rule conditions for each rule, to provide a really flexible and powerful URL manipulation mechanism. The URL manipulations can depend on various tests, of server variables, environment variables, HTTP headers, or time stamps. Even external database lookups in various formats can be used to achieve highly granular URL matching.

This module operates on the full URLs (including the path-info part) both in per-server context (httpd.conf) and per-directory context (.htaccess) and can generate query-string parts on result. The rewritten result can lead to internal sub-processing, external request redirection or even to an internal proxy throughput.

Further details, discussion, and examples, are provided in the detailed mod_rewrite documentation.

Directives

• RewriteBase
• RewriteCond
• RewriteEngine
• RewriteLock
• RewriteLog
• RewriteLogLevel
• RewriteMap
• RewriteOptions
• RewriteRule

If you aren't already comfortable using mod_rewrite then I recommend this excellent mod_rewrite guide by one of my favorite mod_rewrite gurus that I've met.

htaccess Guide Sections

• htaccess tricks for Webmasters
• HTTP Header control with htaccess
• PHP on Apache tips and tricks
• SEO Redirects without mod_rewrite
• mod_rewrite examples, tips, and tricks
• HTTP Caching and Site Speedups
• Authentication on Apache
• htaccess Security Tricks and Tips
• SSL tips and examples
• Variable Fun (mod_env) Section
• .htaccess Security with MOD_SECURITY
• SetEnvIf and SetEnvIfNoCase Examples

« Search Engine Friendly Redirects | .htaccess Tutorial Index | » Speed up your site with Caching and cache-control

Htaccess Rewrites – Rewrite Tricks and Tips originally appeared on AskApache.com

This is part of the GRUB article on the Arch Linux wiki that I contributed. As of now, just a copy.

The grub menu.lst provides for a convenient way to add a number of entries with extended kernel parameters to configure all sorts of advanced settings to enable you to quickly and conveniently boot into your existing system with varying levels of debugging output. It's very easy and useful to create several levels of debugging just by adding additional entries to your grub configuration. And if you ever have issues or problems down the road due to a power-failure or hardware failure, it can save you hours of trouble, and of course nothing can beat debugging output when it comes to learning about your system.

Useful Menu.lst Entries

If you are interested in debugging, then you deserve some grub entries for powerusers, here are a few that I like (just add to your menu.lst).

title Shutdown the Computer
halt
 
title Reboot the Computer
reboot
 
title Command Line
commandline
 
title Install GRUB to hd0 MBR
root (hd0,0)
setup (hd0)
 
title Matrix
color green/black light-green/green
 
title Scan for /boot/grub/menu.lst
find --set-root --ignore-floppies /boot/grub/menu.lst
configfile /boot/grub/menu.lst
 
title Scan for /boot/menu.lst
find --set-root --ignore-floppies /menu.lst
configfile /boot/menu.lst
 
# http://www.vortex.prodigynet.co.uk/x86test/
title    Run x86test (CPU Info)
kernel /boot/x86test_zImage.bin
#wget http://www.vortex.prodigynet.co.uk/x86test/x86test_zImage.bin
 
# http://www.memtest.org/
title    Run memtest86+ (Memory Testing)
kernel /boot/memtest86+-1.70.bin

Light Debug

A quick way to see more verbose messages on your console is to bootup your normal grub entry after appending verbose to the kernel line. This simple word added to your kernel line turns on more logging thanks to the /etc/rc.sysinit file, which at the top of the file runs:

if /bin/grep -q " verbose" /proc/cmdline; then /bin/dmesg -n 8; fi

Very simple way to get a bit more messages and debug output in your logs.

title  Arch Linux DEBUG Light
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro rootwait verbose
initrd /kernel26.img

Medium Debug

This example menu.lst entry turns on real logging that is set by the kernel and not in an init script. Adding the debug kernel parameter to your kernel line is recognized by a lot of linux internals and enables quite a bit of debugging compared to the default.

title Arch Linux DEBUG Medium
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro rootdelay=5 panic=10 debug
initrd /kernel26.img

Heavy Debug

An even more impressive kernel parameter is the ignore_loglevel, which causes the system to ignore any loglevel and keeps the internal loglevel at the maximum debugging level, basically rendering dmesg unable to lower the debug level.

title Arch Linux DEBUG Heavy
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro rootdelay=5 panic=10 debug ignore_loglevel
initrd /kernel26.img

Extreme Debug

If the "Heavy Debug" seemed like a lot of output, thats about 1/2 of the logging that occurs with this example. This does a couple things, it uses the earlyprintk parameter to setup your kernel for "early" "printing" of messages to your "vga" screen. The ,keep just lets it stay on the screen longer. This will let you see logs that normally are hidden due to the boot-up process. This also changes the log buffer length to 10MB, and also instructs that any fatal signals be printed with print_fatal_signals. The last one, sched_debug, you can look up in the very excellent kernel documentation on kernel parameters.

title Arch Linux DEBUG Extreme
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro debug ignore_loglevel log_buf_len=10M print_fatal_signals=1 LOGLEVEL=8 earlyprintk=vga,keep sched_debug
initrd /kernel26.img

Insane Debug

The first few debugging examples showed some really nice kernel parameters to turn on really verbose debugging. This kind of debugging is absolutely critical if you want to max out your system or just learn more about what is going on behind the scenes. But there is a final trick that is my favorite, it's the ability to set both environment variables, and more importantly, module parameters at boot.

As an example, here is the boot line that I am using at the moment on an older Dell Desktop, just to illustrate module parameters and environment vars.

title  Arch Linux X-256
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro rootwait pause_on_oops=5 panic=60 i915.modeset=1 no_console_suspend ipv6.disable=1 TERM=xterm-256color quiet 5
initrd /kernel26.img

Since it's low on both memory and CPU, I disable ipv6. I also turn on kernel modesetting for the i915 video card, set my terminal to be xterm-256color, and boot straight into X. This lets me use a very optimized arch-linux configuration, amazing how fast thanks to using slim as the login manager, ratpoison as my window manager, and terminal with tmux as my login shell, all from boot, as the pstree shows (plus Synergy!).

init,1
  |-slim,3096
  |   |-X,3098 -nolisten tcp vt07 -auth /var/run/slim.auth
  |   `-ratpoison,3107,askapache
  |       |-terminal,5341 -x sh -c exec /usr/bin/tmux -2 -l -u -q attach -d -t tmux-askapache
  |       |   |-bash,11165
  |       |   |-tmux,5345 -2 -l -u -q attach -d -t tmux-askapache
  |       |   `-{terminal},5346
  |       `-xscreensaver,3113 -no-splash
  |-synergyc,6121,galileo -f --name galileo-fire --restart 10.66.66.2:26666
  |
  `-tmux,5348,askapache -2 -l -u -q attach -d -t tmux-askapache
      |-bash,5351
      |   `-ssh,9969 lug@askapache.com
      `-bash,5868
         `-vim,11149 -p sda1/grub/menu.lst /boot/grub/menu.lst

That kind of optimized system is only possible if you first can figure out your system, by debugging both the kernel as previously illustrated, debugging the init process, and most importantly, by debugging the modules enabled for your system's hardware/firmware/software. Debugging modules is challenging but worth the effort, and then you are able to do some truly insane debugging from grub like the following example, note that the actual grub entry is all on one line, but I split it into 4 lines so you could see it all. This basically turns on every module on this little Dell desktop to be at the absolute max debug level. There is so much logging when I boot this that the system grinds to a halt and is slower than a TI-89 calculator (See Improve Boot Performance).

title  Arch Linux DEBUG INSANE
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro rootwait ignore_loglevel debug debug_locks_verbose=1 sched_debug initcall_debug mminit_loglevel=4 udev.log_priority=8
       loglevel=8 earlyprintk=vga,keep log_buf_len=10M print_fatal_signals=1 apm.debug=Y i8042.debug=Y drm.debug=1 scsi_logging_level=1 usbserial.debug=Y
       option.debug=Y pl2303.debug=Y firewire_ohci.debug=1 hid.debug=1 pci_hotplug.debug=Y pci_hotplug.debug_acpi=Y shpchp.shpchp_debug=Y apic=debug
       show_lapic=all hpet=verbose lmb=debug pause_on_oops=5 panic=10 sysrq_always_enabled
initrd /kernel26.img

A couple key items from that grub entry are sysrq_always_enabled which forces on the sysrq magic, which really is a lifesaver when debugging at this level as your machine will freeze/stop-responding sometimes and it's nice to use sysrq to kill all tasks, change the loglevel, unmount all filesystems, or do a hard reboot. Another key parameter is the initcall_debug, which debugs the init process in excruciating detail. Very useful at times. The last parametery I find very useful is the udev.log_priority=8 to turn on udev logging.

Break Into Init

For instance, If you add break=y to your kernel cmdline, init will pause early in the boot process (after loading modules) and launch an interactive sh shell which can be used for troubleshooting purposes. (Normal boot continues after logout.) This is very similar to the shell that shows up if your computer gets turned off before it is able to shutdown properly. But using this parameter lets you enter into this mode differently at will.

title  Arch Linux Init Break
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro rootwait break=y
initrd /kernel26.img

Debugging init

This awesome parameter udev.log_priority=8 does the same thing as editing the file /etc/udev/udev.conf except it executes earlier, turning on debugging output for udev. If you want to know your hardware, that is the key parameter right there. Another trick is if you change the /etc/udev/udev.conf to be verbose, then you can make your initrd image include that file to turn on verbose udeb debugging by adding it to your {{Filename|/etc/mkinitcpio.conf} like:

FILES="/etc/modprobe.d/modprobe.conf /etc/udev/udev.conf"

, which on arch is as easy as

# mkinitcpio -p kernel26

Debugging udev is key because the initrd performs a root change at the end of its run to usually launch a program like /sbin/init as part of a chroot, and unless the new file system has a valid /dev directory, udev must be initialized before invoking chroot in order to provide /dev/console.

exec chroot . /sbin/init <dev/console >dev/console 2>&1

So basically, you aren't able to view the logs that are generated before /dev/console is initialized by udev or by a special initrd you compiled yourself. One method the kernel developers use to be able to still get the log messages generated before /dev/console is available is to provide an alternative console that you can enable or disable from grub.

Net Console

If you read through the kernel documentation regarding debugging, you will hear about Netconsole, which can be loaded from the kernel line in GRUB, compiled into your kernel, or loaded at runtime as a module. Having a netconsole entry in your menu.lst is most excellent for debugging slower computers like old laptops or thin-clients. It's easy to use. Just setup a 2nd computer (running arch) to accept syslog requests on a remote port, very fast and quick to do on arch-linux, 1 line to syslog.conf. Then you could use a log-color-parser like ccze to view all syslog logs, or just tail your everything.log. Then on your laptop, boot up and select the netconsole entry from the grub menu, and you will start seeing as much logging as you want on your syslog system. This logging lets you view even earlier log output than is available with the earlyprintk=vga kernel parameter, as netconsole is used by kernel hackers and developers, so it's very powerful.

title  Arch Linux DEBUG Netconsole
kernel /vmlinuz26 root=/dev/disk/by-label/ROOT ro netconsole=514@10.0.0.2/12:34:56:78:9a:bc debug ignore_loglevel
initrd /kernel26.img

Hijacking cmdline

If you do not have access to GRUB or the kernel boottime cmdline, like on a server or virtual machine, as long as you have root permissions you can still enable this kind of simplistic verbose logging using a neat hack. While you cannot modify the /proc/cmdline even as root, you can place your own cmdline file on top of /proc/cmdline, so that accessing /proc/cmdline actually accesses your file.

For example if I cat /proc/cmdline, I have the following:

root=/dev/disk/by-label/ROOT ro console=tty1 logo.nologo quiet

So I use a simple sed command to replace quiet with verbose like:

sed 's/ quiet/ verbose/' /proc/cmdline > /root/cmdline

Then I bind mount /root/cmdline so that it becomes /proc/cmdline, using the -n option to mount so that this mount won't be recorded in the systems mtab.

mount -n --bind -o ro /root/cmdline /proc/cmdline

Now if I cat /proc/cmdline, I have the following:

root=/dev/disk/by-label/ROOT ro console=tty1 logo.nologo verbose

Advanced Linux Debugging using a Bootloader (GRUB) originally appeared on AskApache.com

We've figured out what mod_rewrite variables look like so we can create rewriterules and condition patterns based on the actual value. This cheatsheet is where we'll lay them all out for quick reference. This cheatsheet changed my life, way more than 301 redirect htaccess.

mod_rewrite Variable Value Cheat-Sheet

Jump to: API_VERSION, AUTH_TYPE, CONTENT_LENGTH, CONTENT_TYPE, DOCUMENT_ROOT, GATEWAY_INTERFACE, HTTPS, HTTP_ACCEPT, HTTP_ACCEPT_CHARSET, HTTP_ACCEPT_ENCODING, HTTP_ACCEPT_LANGUAGE, HTTP_CACHE_CONTROL, HTTP_CONNECTION, HTTP_COOKIE, HTTP_FORWARDED, HTTP_HOST, HTTP_KEEP_ALIVE, HTTP_PROXY_CONNECTION, HTTP_REFERER, HTTP_USER_AGENT, IS_SUBREQ, ORIG_PATH_INFO, ORIG_PATH_TRANSLATED, ORIG_SCRIPT_FILENAME, ORIG_SCRIPT_NAME, PATH, PATH_INFO, PHP_SELF, QUERY_STRING, REDIRECT_QUERY_STRING, REDIRECT_REMOTE_USER, REDIRECT_STATUS, REDIRECT_URL, REMOTE_ADDR, REMOTE_HOST, REMOTE_IDENT, REMOTE_PORT, REMOTE_USER, REQUEST_FILENAME, REQUEST_METHOD, REQUEST_TIME, REQUEST_URI, SCRIPT_FILENAME, SCRIPT_GROUP, SCRIPT_NAME, SCRIPT_URI, SCRIPT_URL, SCRIPT_USER, SERVER_ADDR, SERVER_ADMIN, SERVER_NAME, SERVER_PORT, SERVER_PROTOCOL, SERVER_SIGNATURE, SERVER_SOFTWARE, SSL_CIPHER, SSL_CIPHER_ALGKEYSIZE, SSL_CIPHER_EXPORT, SSL_CIPHER_USEKEYSIZE, SSL_CLIENT_VERIFY, SSL_PROTOCOL, SSL_SERVER_A_KEY, SSL_SERVER_A_SIG, SSL_SERVER_CERT, SSL_SERVER_I_DN, SSL_SERVER_I_DN_C, SSL_SERVER_I_DN_CN, SSL_SERVER_I_DN_L, SSL_SERVER_I_DN_O, SSL_SERVER_I_DN_OU, SSL_SERVER_I_DN_ST, SSL_SERVER_M_SERIAL, SSL_SERVER_M_VERSION, SSL_SERVER_S_DN, SSL_SERVER_S_DN_CN, SSL_SERVER_S_DN_O, SSL_SERVER_S_DN_OU, SSL_SERVER_V_END, SSL_SERVER_V_START, SSL_SESSION_ID, SSL_VERSION_INTERFACE, SSL_VERSION_LIBRARY, THE_REQUEST, TIME, TIME_DAY, TIME_HOUR, TIME_MIN, TIME_MON, TIME_SEC, TIME_WDAY, TIME_YEAR, TZ, UNIQUE_ID

API_VERSION: 20020903:12

RewriteCond %{API_VERSION} ^(.*)$
RewriteRule .* http://www.askapache.com?API_VERSION=%1 [R=307,L]

AUTH_TYPE: Digest

RewriteRule .* - [E=IN_AUTH_TYPE:%{AUTH_TYPE}]
RequestHeader set AUTH_TYPE "%{IN_AUTH_TYPE}e"

CACHE_CONTROL: max-age=0

RewriteCond %{ENV:CACHE_CONTROL} no-cache [NC]
RewriteRule . %{REQUEST_URI}?nocache [L]

CONNECTION: keep-alive

CONTENT_LENGTH: (null)

RewriteCond %{REQUEST_METHOD} =POST
RewriteCond %{HTTP:Content-Length}%{CONTENT_LENGTH} ^$
RewriteRule .* - [F,NS,L]

CONTENT_TYPE: (null)

DOCUMENT_ROOT: /home/webroot/askapache.com

RewriteCond %{DOCUMENT_ROOT}/cache%{REQUEST_URI}/index.html -f
RewriteRule . /cache%{REQUEST_URI}/index.html

HOST: www.askapache.com

RewriteCond %{HTTP_HOST} !^www\.askapache\.com$ [NC]
RewriteRule . http://www.askapache.com%{REQUEST_URI} [R=301,L]

HTTP:

RewriteCond %{HTTP:Accept-Encoding} gzip [NC]
RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI}.gz -f
RewriteRule . %{REQUEST_URI}.gz [L]

HTTPS: off

RewriteCond %{HTTPS} !=on
RewriteRule .* https://%{SERVER_NAME}%{REQUEST_URI} [R=301,L]

HTTP_ACCEPT: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8

HTTP_COOKIE: __qca=1176541205adf28-5553185; ASKAPACHEID=fdadfa4f33e62a878468; __utmc=1df3893

RewriteCond %{HTTP_COOKIE} ^.*autostart=on.*$
RewriteRule ^(.*)\.swf$ /$1\?autostart=true [NE,L]

HTTP_HOST: www.askapache.com

HTTP_REFERER: http://www.askapache.com/pro/mod_rewrite/catch.php?k=i

RewriteCond %{HTTP_REFERER} badhost [NC]
RewriteRule . - [F]

HTTP_USER_AGENT: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9) Firefox/3.0.1

RewriteCond %{HTTP_USER_AGENT} ^.*(Android|2.0\ MMP|240x320|AvantGo|BlackBerry|Blazer|Cellphone|Danger|DoCoMo|Elaine/3.0|EudoraWeb|hiptop|IEMobile|iPhone).*$ [NC]
RewriteRule ^(.+)$ /mobile/$1 [L]

IS_SUBREQ: false

KEEP_ALIVE: 300

PATH: /bin:/usr/bin:/sbin:/usr/sbin

QUERY_STRING: k=i

RewriteCond %{QUERY_STRING} showtime [NC]
RewriteCond T:%{TIME}_TY:%{TIME_YEAR}_TMO:%{TIME_MON}_TWD:%{TIME_WDAY}_TD:%{TIME_DAY}_TH:%{TIME_HOUR}_TMI:%{TIME_MIN}_TS:%{TIME_SEC} ^(.*)$
RewriteRule .* http://%{HTTP_HOST}%{REQUEST_URI}?time=%1 [R,L]

REMOTE_ADDR: 22.162.134.211

RewriteCond %{REMOTE_ADDR} !^22\.162\.134\.211$
RewriteRule . http://www.askapache.com/maintenance-in-progress.html [R=307,L]

REMOTE_HOST: 22.162.134.211

REMOTE_PORT: 4220

REMOTE_USER: askapache

RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization}]

REQUEST_FILENAME: /home/webroot/askapache.com/pro/mod_rewrite/index.php

REQUEST_METHOD: GET

RewriteCond %{REQUEST_METHOD} !^(POST|GET|HEAD|PROPFIND|OPTIONS)$
RewriteRule .* - [F,L]

REQUEST_PROTOCOL: HTTP/1.1

RewriteCond %{REQUEST_PROTOCOL} !^HTTP/(0\.9|1\.[01])$
RewriteRule . [F,L]

REQUEST_URI: /pro/mod_rewrite/index.php

RewriteCond %{REQUEST_URI} ^(robots\.txt|favicon\|ico)$ [NC]
RewriteRule . - [S=1]
RewriteCond %{HTTP_HOST} ^www
RewriteRule .* http://%{SERVER_NAME}%{REQUEST_URI} [R=301,L]

SCRIPT_FILENAME: /home/webroot/askapache.com/pro/mod_rewrite/index.php

SCRIPT_GROUP: daemong

SCRIPT_URI: http://www.askapache.com/pro/mod_rewrite/index.php

SCRIPT_URL: /pro/mod_rewrite/index.php

SCRIPT_USER: askapache

SERVER_ADDR: 208.113.134.190

SERVER_ADMIN: webmaster@askapache.com

SERVER_NAME: www.askapache.com

SERVER_PORT: 80

SERVER_PROTOCOL: HTTP/1.1

SERVER_SOFTWARE: Apache/2.0.61 (Unix) PHP/5.5 OpenSSL/0.9.7e

SSL_CIPHER: DHE-RSA-AES256-SHA

SSL_CIPHER_ALGKEYSIZE: 256

SSL_CIPHER_EXPORT: false

SSL_CIPHER_USEKEYSIZE: 256

SSL_CLIENT_VERIFY: NONE

SSL_PROTOCOL: TLSv1

SSL_SERVER_A_KEY: rsaEncryption

SSL_SERVER_A_SIG: sha1WithRSAEncryption

SSL_SERVER_CERT: -----BEGIN CERTIFICATE----- ... MIIFkTC ... -----END CERTIFICATE-----

SSL_SERVER_I_DN: /C=US/ST=Arizona/L=Scottsdale/O=Starfield Technologies, Inc./OU=http://certificates.starfieldtech.com/repository/CN=Starfield Secure Certification Authority/serialNumber=10688435

SSL_SERVER_I_DN_C: US

SSL_SERVER_I_DN_CN: Starfield Secure Certification Authority

SSL_SERVER_I_DN_L: Scottsdale

SSL_SERVER_I_DN_O: Starfield Technologies, Inc.

SSL_SERVER_I_DN_OU: http://certificates.starfieldtech.com/repository

SSL_SERVER_I_DN_ST: Arizona

SSL_SERVER_M_SERIAL: 042840B88A2352

SSL_SERVER_M_VERSION: 3

SSL_SERVER_S_DN: /O=www.askapache.com/OU=Domain Control Validated/CN=www.askapache.com

SSL_SERVER_S_DN_CN: www.askapache.com

SSL_SERVER_S_DN_O: www.askapache.com

SSL_SERVER_S_DN_OU: Domain Control Validated

SSL_SERVER_V_END: Jul 14 16:53:43 2012 GMT

SSL_SERVER_V_START: Jul 14 20:25:17 2010 GMT

SSL_SESSION_ID: 4184083DD1C74547553018174950D88987BD7ED03CE54EBB6638539C34814376

SSL_VERSION_INTERFACE: mod_ssl/2.2.16

SSL_VERSION_LIBRARY: OpenSSL/0.9.8e-fips-rhel5

THE_REQUEST: GET /pro/mod_rewrite/index.php?k=i HTTP/1.1

RewriteCond %{THE_REQUEST} ^(GET|POST)\ /.*\?(s|search)=(.+)\ HTTP/ [NC]
RewriteRule .* http://www.askapache.com/search/%3/? [R=302,L,NE]

TIME: 20080915152142

RewriteCond %{QUERY_STRING} showtime [NC]
RewriteCond T:%{TIME}_TY:%{TIME_YEAR}_TMO:%{TIME_MON}_TWD:%{TIME_WDAY}_TD:%{TIME_DAY}_TH:%{TIME_HOUR}_TMI:%{TIME_MIN}_TS:%{TIME_SEC} ^(.*)$
RewriteRule .* http://%{HTTP_HOST}%{REQUEST_URI}?time=%1 [R,L]

TIME_DAY: 15

TIME_HOUR: 15

TIME_MIN: 21

TIME_MON: 09

TIME_SEC: 42

TIME_WDAY: 1

TIME_YEAR: 2008

UNIQUE_ID: qOr5tEBvcm8AAE-VoiUAAAAQ

This article is meant to prepare us for the advanced mod_rewrite examples that are soon to be published. The upcoming article is going to be examples using mod_rewrite to achieve some crazy stuff... Here the focus is on identifying mod_rewrite variables and defining the limits of the module by checking the mod_rewrite source code.

For a broader mod_rewrite cheat sheet, check this printable cheat sheet.

Directives in Mod_Rewrite

RewriteEngine

RewriteEngine on|off

On or Off to enable or disable (default) the whole rewriting engine

RewriteOptions

RewriteOptions Options

List of option strings to set

RewriteBase

RewriteBase URL-path

the base URL of the per-directory context

RewriteCond

RewriteCond TestString CondPattern

an input string and a to be applied regexp-pattern

RewriteRule

RewriteRule Pattern Substitution [flags]

an URL-applied regexp-pattern and a substitution URL

RewriteMap

RewriteMap MapName MapType:MapSource

a mapname and a filename

RewriteLock

RewriteLock file-path

the filename of a lockfile used for inter-process synchronization

RewriteLog

RewriteLog file-path

the filename of the rewriting logfile

RewriteLogLevel

RewriteLogLevel Level

the level of the rewriting logfile verbosity (0=none, 1=std, .., 9=max)

RewriteRule Flags

C

Using the [Chain], or [C] flag, allows you to indicate that several rules should be chained together as a single logical transation. This is usually used when a transformation is sufficiently complicated to warrant breaking into several smaller steps.

CO

cookie|CO=Name:Value:Domain[:Lifetime[:Path]]

This sets a cookie on the client's browser. The cookie's name is specified by NAME and the value is VAL. The domain field is the domain of the cookie, such as '.apache.org',the optional lifetime is the lifetime of the cookie in minutes, and the optional path is the path of the cookie.

E

'env|E=VAR:VAL' (set environment variable)

RewriteRule (root|cmd)\.exe - [E=worm:nimda]

F

'forbidden|F' (force URL to be forbidden)

G

'gone|G' (force URL to be gone)

H

'handler|H=Content-handler' (force Content handler)

L

'last|L' (last rule)

N

'next|N' (next round)

NC

'nocase|NC' (no case)

NE

'noescape|NE' (no URI escaping of output)

NS

'nosubreq|NS' (not for internal sub-requests)

P

'proxy|P' (force proxy)

PT

'passthrough|PT' (pass through to next handler)

QSA

'qsappend|QSA' (query string append)

R

'redirect|R  [=code]' (force redirect)

S

'skip|S=num' (skip next rule(s))

This flag forces the rewriting engine to skip the next num rules in sequence, if the current rule matches. Use this to make pseudo if-then-else constructs: The last rule of the then-clause becomes skip=N, where N is the number of rules in the else-clause. (This is not the same as the 'chain|C' flag!)

T

'type|T=MIME-type' (force MIME type)

Force the MIME-type of the target file to be MIME-type. This can be used to set up the content-type based on some conditions. For example, the following snippet allows .php files to be displayed by mod_php if they are called with the .phps extension:

Rules and Conditions Processing Order

1. The Pattern of the RewriteRule (^/.*$) is checked first.
2. If the pattern matches, then the RewriteCond's are checked.
3. If the RewriteConditions also match, the RewriteRule is applied.

RewriteRule Special Variables

1. ENV_
2. SSL_
3. HTTP_
4. LA-U_
5. LA-F_

RewriteCond Tests

• f - FILE_EXISTS
• s - FILE_SIZE
• l - FILE_LINK
• d - FILE_DIR
• x - FILE_XBIT
• U - LU_URL
• F - LU_FILE
• > - STR_GT
• < - STR_LT
• = - STR_EQ

Special Rewrite Redirects

1. "permanent" - HTTP_MOVED_PERMANENTLY
2. "temp" - HTTP_MOVED_TEMPORARILY
3. "seeother" - HTTP_SEE_OTHER
4. digit

Recognized by Mod_Rewrite

1. ajp://
2. balancer://
3. ftp://
4. gopher://
5. http://
6. https://
7. ldap://
8. mailto:
9. news:
10. nntp://

Mod_Rewrite Variables, from Source

• TIME - %04d%02d%02d%02d%02d%02d
• HTTPS - flag ? "on" : "off"
• TIME_DAY
• TIME_SEC
• TIME_MIN
• TIME_HOUR
• TIME_MON
• TIME_WDAY
• TIME_YEAR
• IS_SUBREQ - (main ? "true" : "false");
• PATH_INFO - path_info;
• AUTH_TYPE - ap_auth_type;
• HTTP_HOST - lookup_header("Host", ctx);
• SERVER_NAME - ap_get_server_name(r);
• REMOTE_ADDR - connection->remote_ip;
• SERVER_ADDR - connection->local_ip;
• HTTP_ACCEPT - lookup_header("Accept", ctx);
• THE_REQUEST - the_request;
• API_VERSION - "%d:%d",MODULE_MAGIC_NUMBER_MAJOR,MODULE_MAGIC_NUMBER_MINOR);
• HTTP_COOKIE - lookup_header("Cookie", ctx);
• SERVER_PORT - ap_get_server_port(r);
• REMOTE_HOST
• REMOTE_NAME, NULL);
• REMOTE_PORT - r->connection->remote_addr->port
• REMOTE_USER - user;
• SCRIPT_USER - "<unknown>";
• APR_FINFO_USER
• REQUEST_URI - uri;
• SCRIPT_GROUP - "<unknown>";
• REMOTE_IDENT - ap_get_remote_logname(r);
• HTTP_REFERER - lookup_header("Referer", ctx);
• QUERY_STRING - args;
• SERVER_ADMIN - server->server_admin;
• DOCUMENT_ROOT - ap_document_root(r);
• HTTP_FORWARDED - lookup_header("Forwarded", ctx);
• REQUEST_METHOD - method;
• HTTP_USER_AGENT - lookup_header("User-Agent", ctx);
• SCRIPT_FILENAME - same as request_filename
• REQUEST_FILENAME - same as script_filename
• SERVER_PROTOCOL - protocol
• SERVER_SOFTWARE - ap_get_server_banner();
• HTTP_PROXY_CONNECTION - lookup_header("Proxy-Connection", ctx);

REGEX Rewrite Guides

• Mod_Rewrite: Flags, Rules, Conditions, Tutorial and Variables
• Using Regular Expressions
• RewriteRule (mod_rewrite) guide

Mod_Rewrite Terms and Definitions

pattern

the RegExp pattern string

regexp

the RegExp pattern compilation

flags

Flags which control the substitution

forced_mimetype

forced MIME type of substitution

forced_handler

forced content handler of subst.

forced_responsecode

forced HTTP response status

env

added environment variables

cookie

added cookies

skip

number of next rules to skip

state

the RewriteEngine state

options

the RewriteOption state

rewritelogfile

the RewriteLog filename

rewritelogfp

the RewriteLog open filepointer

rewritelog: level

the RewriteLog level of verbosity

rewritemaps

the RewriteMap entries

rewriteconds

the RewriteCond entries (temp.)

rewriterules

the RewriteRule entries

directory

the directory where it applies

baseurl

the base-URL where it applies

Mod_Rewrite Errors

• Options FollowSymLinks or SymLinksIfOwnerMatch is off which implies that RewriteRule directive is forbidden: %s
• RewriteCond: bad argument line
• RewriteCond: NoCase option for non-regex pattern %s is not supported and will be ignored.
• RewriteCond: cannot compile regular expression
• RewriteRule: invalid HTTP response code %s for flag R
• RewriteRule: unknown flag
• RewriteRule: cannot compile regular expression
• RewriteOptions: MaxRedirects option has been removed in favor of the global LimitInternalRecursion directive and will be ignored.
• RewriteOptions: unknown option
• RewriteMap: bad path to txt map:
• RewriteMap: bad path to rnd map:
• RewriteMap: bad map:
• RewriteMap: bad path to dbm map:
• RewriteMap: dbm type
• RewriteMap: bad path to prg map:
• RewriteMap: internal map not found:
• RewriteMap: bad path to txt map:
• RewriteMap: file for map not found:
• Invalid RewriteLock path
• RewriteBase: only valid in per-directory config files
• RewriteBase: empty URL not allowed
• RewriteBase: argument is not a valid URL
• RewriteCond: bad flag delimiters
• RewriteCond: unknown flag
• RewriteLog and RewriteLogLevel are not supported by this build of mod_rewrite because it was compiled using the -DREWRITELOG_DISABLED compiler option. You have to recompile mod_rewrite WITHOUT this option in order to use the rewrite log.
• mod_rewrite: Invalid RewriteLog path %s
• mod_rewrite: could not open reliable pipe to RewriteLog filter %s
• mod_rewrite: Invalid RewriteLog path %s
• mod_rewrite: could not open RewriteLog file %s
• mod_rewrite: Running external rewrite maps without defining a RewriteLock is DANGEROUS!
• mod_rewrite: could not start RewriteMap program %s
• mod_rewrite: cant access text RewriteMap file %s
• mod_rewrite: cant access DBM RewriteMap file %s
• mod_rewrite: Parent could not create RewriteLock file %s
• mod_rewrite: Parent could not set permissions on RewriteLock check User and Group directives
• mod_rewrite: could not create rewrite_log_lock
• mod_rewrite: Could not set permissions on rewrite_log_lock check User and Group directives
• mod_rewrite: could not init rewrite_mapr_lock_acquire in child
• mod_rewrite: could not init rewrite log lock in child
• mod_rewrite: could not init map cache in child
• split uri=%s -> uri=%s, args=%s
• reduce %s -> %s
• strip matching prefix: %s -> %s
• add subst prefix: %s -> %s
• cant open RewriteMap file, see error log
• cache lookup FAILED, forcing new map lookup
• map lookup FAILED: map=%s[txt] key=%s
• map lookup OK: map=%s[txt] key=%s -> val=%s
• cache lookup OK: map=%s[txt] key=%s -> val=%s
• randomly chosen the subvalue `%s
• cant open DBM RewriteMap file, see error log
• cache lookup FAILED, forcing new map lookup
• map lookup FAILED: map=%s[dbm] key=%s
• map lookup OK: map=%s[dbm] key=%s -> val=%s
• cache lookup OK: map=%s[dbm] key=%s -> val=%s
• map lookup FAILED: map=%s key=%s
• map lookup OK: map=%s key=%s -> val=%s
• map lookup FAILED: map=%s key=%s
• map lookup OK: map=%s key=%s -> val=%s
• lookahead: path=%s var=%s -> val=%s
• lookahead: path=%s var=%s -> val=%s
• RESULT=%s
• escaping backreference %s to %s
• setting env variable %s to %s
• setting cookie %s, cookie
• skipping already set cookie %s
• RewriteCond URI (-U) check: path=%s -> status=%d
• RewriteCond file (-F) check: path=%s -> file=%s status=%d
• RewriteCond: input=%s pattern=%s%s%s%s => %s
• remember %s to have MIME-type %s
• remember %s to have Content-handler %s
• add path info postfix: %s -> %s%s
• strip per-dir prefix: %s -> %s
• applying pattern %s to uri %s
• rewrite %s -> %s, ctx->uri
• forcing responsecode %d for %s
• add per-dir prefix: %s -> %s%s
• forcing proxy-throughput with %s
• explicitly forcing redirect with %s
• implicitly forcing redirect (rc=%d) with %s
• forcing %s to get passed through to next API URI-to-filename handler
• init rewrite engine with requested uri %s
• go-ahead with proxy request %s [OK]
• dconf->directory,trying to replace prefix %s with %s
• escaping %s for redirect
• redirect to %s [REDIRECT/%d]
• initial URL equal rewritten URL: %s [IGNORING REWRITE]
• dconf->directory, trying to replace prefix %s with %s
• strip document_root prefix: %s -> %s
• internal redirect with %s [INTERNAL REDIRECT]
• pass through %s
• force filename %s to have MIME-type %s
• force filename %s to have the Content-handler %s,
• init rewrite engine with requested uri %s
• init rewrite engine with passed filename %s. Original uri = %s
• uri already rewritten. Status %s, Uri %s, %s
• attempt to make remote request from mod_rewrite without proxy enabled: %s
• go-ahead with proxy request %s [OK]
• escaping %s for redirect
• redirect to %s [REDIRECT/%d]
• local path result: %s
• prefixing with document_root of %s FAILED
• prefixed with document_root to %s
• go-ahead with %s [OK]
• pass through %s

URL Rewriting Module

This module uses a rule-based rewriting engine (based on a regular-expression parser) to rewrite requested URLs on the fly.

It supports an unlimited number of additional rule conditions (which can operate on a lot of variables, even on HTTP headers) for granular matching and even external database lookups (either via plain text tables, DBM hash files or even external processes) for advanced URL substitution.

It operates on the full URLs (including the PATH_INFO part) both in per-server context (httpd.conf) and per-dir context (.htaccess) and even can generate QUERY_STRING parts on result. The rewriting result finally can lead to internal subprocessing, external request redirection or even to internal proxy throughput.

This module was originally written in April 1996 and gifted exclusively to the The Apache Software Foundation in July 1997 by

Ralf S. Engelschall rse [at] engenschall.com

Mod_Rewrite Variables Cheatsheet originally appeared on AskApache.com