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.

Rangel

Check this link: httpd.apache.org/docs/current/rewrite/flags.html#flag_qsa – Arithmomancy

QSA flag in mod_rewrite : helponnet.com/2021/04/27/htaccess-qsa-flag – Alcoholize

Answer 1

.htaccess flag list

• C (chained with next rule)
• CO=cookie (set specified cookie)
• E=var:value (set environment variable var to value)
• F (forbidden - sends a 403 header to the user)
• G (gone - no longer exists)
• H=handler (set handler)
• L (last - stop processing rules)

Last rule: instructs the server to stop rewriting after the preceding directive is processed.

• N (next - continue processing rules)
• NC (case insensitive)
• NE (do not escape special URL characters in output)
• NS (ignore this rule if the request is a subrequest)
• P (proxy - i.e., apache should grab the remote content specified in the substitution section and return it)
• PT (pass through - use when processing URLs with additional handlers, e.g., mod_alias)
• R (temporary redirect to new URL)
• R=301 (permanent redirect to new URL)
• QSA (append query string from request to substituted URL)
• S=x (skip next x rules)
• T=mime-type (force specified mime type)

Flags are added to the end of a rewrite rule to tell Apache how to interpret and handle the rule. They can be used to tell apache to treat the rule as case-insensitive, to stop processing rules if the current one matches, or a variety of other options. They are comma-separated, and contained in square brackets.

Prosimian

You got my +1, but for a perfect answer, it would be nice to provide a link to Apache's official resources, e.g. httpd.apache.org/docs/current/mod/mod_rewrite.html#RewriteRule (or wherever your reference was) – Bimanous

Answer 2

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.

Upbow

QSA replaces ? to &, making it impossible to distinguish between /page&foobar vs /page?foobar. How can I stop QSA from replacing ? to &? – Cooke

@Cooke if you need to encode the query string in the new query string, then you may want to look into using the %{QUERY_STRING} variable instead of using QSA – Upbow

Answer 3

Example of [L,QSA]

Before: https://example.com/index.php?user=robert

RewriteEngine On
RewriteRule ^user/([^/]+)?$ index.php?user=$1 [L,QSA]

After: https://example.com/user/robert?query=value

You can also use other query too.

Like: robert?query=value&query2=value2&query3=value3

Stickler