In this blog post I will be explaining how it is possible to re-write urls on an apache web server using your .htaccess file. This allows you to use ‘pretty’ links such as http://www.example.org/category/item.html in place of ‘ugly’ links such as http://www.example.org/catid=23&itemid=54

Aside from the fact that the pretty links obviously look better, they can help users navigate the site and are more search engine friendly. They provide keywords for the pages and can also provide a site hierarchy.

Some users navigate the site by removing sections of the URL, for example:

http://www.example.org/category/item.html -> http://www.example.org/category/

In a well designed site using URL re-writing this should not be a problem.

The Tutorial:

To get started, the below line should be added above the rewrite rules in your .htaccess file (if it is not there already) .
RewriteEngine on

We will assume that the sites URL’s are arranged as so:

http://www.example.org/index.php?pageid=x

http://www.example.org/index.php?catid=x

http://www.example.org/index.php?catid=x&itemid=y

In the sites database a field should be added to hold a ‘slug’ – unique URL friendly title – for each page/category. The site linking needs to be changed so that the x/y above contains the slug e.g.

as well as the link

http://www.example.org/index.php?pageid=2

the following can be used:

http://www.example.org/index.php?slug=about-us

the argument in the url does not have to be slug, it could be anything e.g.

http://www.example.org/index.php?title=about-us

and so we have urls such as these:

http://www.example.org/index.php?slug=x

http://www.example.org/index.php?catslug=x

http://www.example.org/index.php?catslug=x&itemslug=y

Rewrite rules like these should then need to be added to the .htaccess file
RewriteRule ^([0-9A-Za-z-]+).html$ index.php?slug=$1 [L,QSA]
RewriteRule ^([0-9A-Za-z-]+)/$ index.php?catslug =$1 [L,QSA]
RewriteRule ^([0-9A-Za-z-]+)/([0-9A-Za-z-]+).html$ index.php?catslug =$1&itemslug=$2 [L,QSA]

In the
([0-9A-Za-z-]+)

regular expression, the brackets
()

select the regular expression between them.
[0-9A-Za-z-]

allows all alphanumeric characters and hyphens
(-)

we could add underscores
(_)

like this
[0-9A-Za-z-_]

for example.
The plus after the square bracket expression means 1 or more instances.
So
([0-9A-Za-z-]+)

looks for and selects a group of one or more alphanumeric characters/hyphens. The regular expression selects everything between the previous and next part of the link. So
^([0-9A-Za-z-]+).htm

Would select ‘abcdef’ from the url ‘http://www.example.org/abcdef.html’

This is just a very simple guide to regular expression, look out for an upcoming post explaining regular expressions in more detail.

The regular expression selection is referenced using
$1

, for each subsequent regular expression the number is incremented.

i.e.
RewriteRule ^([0-9A-Za-z-]+)/([0-9A-Za-z-]+).html$ index.php?catslug =$1&itemslug=$2 [L,QSA]

These above rules will then take a link such as

http://www.example.org/index.php?slug=about-us

and show

http://www.example.org/about-us.html

and

http://www.example.org/index.php?catslug=urls

and show

http://www.example.org/urls/

and

http://www.example.org/index.php?catslug=urls&itemslug=re-writing

and show

http://www.example.org/urls/re-write.html

The linking within the site should therefore be using the links of the format

http://www.example.org/urls/re-write.html

Each page should also automatically generate a canonical tag of the format
<link rel="canonical" href="http://www.example.org/url-of/page.html" />

at the top, therefore if any search engine spiders visit the existing links of the format http://www.example.org/index.php?catslug=urls&itemslug=re-writing they will know about the new link i.e. http://www.example.org/urls/re-write.html
and change the cached url to the new one.

Another example of re-writing

http://www.example.org/index.php?pageslug=x

http://www.example.org/index.php?catslug=x

http://www.example.org/index.php?itemslug=x

RewriteRule ^([0-9A-Za-z-]+).html$ index.php?slug=$1 [L,QSA]
RewriteRule ^category/([0-9A-Za-z-]+).html$ index.php?catslug =$1 [L,QSA]
RewriteRule ^item/([0-9A-Za-z-]+).html$ index.php?itemslug=$1 [L,QSA]

Will give urls such as

http://www.example.org/x.html

http://www.example.org/category/x.html

http://www.example.org/item/x.html

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