.htaccess - What is L in [QSA, L] in htaccess

Question

QSA means that if there's a query string passed with the original URL, it will be appended to the rewrite (olle?p=1 will be rewritten as index.php?url=olle&p=1.

L means if the rule matches, don't process any more RewriteRules below this one.

Hi, what are some easy examples to explain the use of L? I can't seem to grasp this explanation above. Any help will be highly appreciated. Thanks.

Answer 1

The QSA flag means to append an existing query string after the URI has been rewritten. Example:

URL=http://example.com/foo/bar?q=blah

Rule:

RewriteRule ^foo/(.*)$ /index.php?b=$1

Result=/index.php?b=bar

Notice how the q=blah is gone. Because the existing query string is dropped in favor of the one in the rule's target, (b=$1). Now if you include a QSA flag:

RewriteRule ^foo/(.*)$ /index.php?b=$1 [QSA]

The result becomes=/index.php?b=bar&q=blah

---

The L flag simply means to stop applying any rules that follow. Given the same URL, http://example.com/foo/bar?q=blah, and given the rules:

RewriteRule ^foo - 

RewriteCond %{REQUEST_URI} !^/bar.php
RewriteRule ^(.*)$ /bar.php?z=$1 

The first rule gets applied and the URI gets passed through unchanged (via the - target). The rewrite engine then processes the next rule, and the URI gets rewritten to /bar.php?z=foo/bar. What happens when you add an L to the end:

RewriteRule ^foo - [L]

RewriteCond %{REQUEST_URI} !^/bar.php
RewriteRule ^(.*)$ /bar.php?z=$1 

The URL http://example.com/foo/bar gets passed through untouched from the first rule, then stops because of the L flag. If the URL is http://example.com/something/else then the first rule doesn't match and the second rule gets applied, rewriting the URI to: /bar.php?z=something/else

Note that since the rewrite engine loops through all the rules until the URI stops changing, the L flag will not prevent the looping, only any further rules from getting applied in the current iteration.