URL Rewritting in htcaccess

I recently gone through a source code of php and found this code in .htaccess in root

RewriteEngine On
RewriteBase /

RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteRule ^([a-zA-Z0-9-]+)/?$ ?menu=$1 [L,QSA]

RewriteRule ^users/([a-zA-Z0-9-/_.[]()@$]+)/$ ?menu=users&user=$1 [L,QSA]
RewriteRule ^users/([a-zA-Z0-9-/_.[]()@$]+)$ ?menu=users&user=$1 [L,QSA]
RewriteRule ^bans/([a-zA-Z0-9-/_.[]()@$]+)/$ ?menu=bans&banuser=$1 [L,QSA]
RewriteRule ^bans/([a-zA-Z0-9-/_.[]()@$]+)$ ?menu=bans&banuser=$1 [L,QSA]

Please,can someone explain me why it is written twice instead once?

Thanks.

Answer

If you look closely at those lines and compare them character-by-character you’ll notice that “doubled” lines actually not identical. I assume that, for example:

RewriteRule ^users/([a-zA-Z0-9-/_.[]()@$]+)/$ ?menu=users&user=$1 [L,QSA]
RewriteRule ^users/([a-zA-Z0-9-/_.[]()@$]+)$ ?menu=users&user=$1 [L,QSA]

differ only by / character to take into account cases when one can query for users/some_user/ and users/someuser (with or without trailing slash). This is common thing to take into account, although it might be addressed at different levels – webserver or framework ones (or even both).

According to RegExp rules, putting a ? sign makes the preceding character optional, which allows you to replace those “duplicates” from above with e.g.:

RewriteRule ^users/([a-zA-Z0-9-/_.[]()@$]+)/?$ ?menu=users&user=$1 [L,QSA]

which should be sufficient, but needs testing.