{"id":8738,"date":"2016-01-23T16:34:37","date_gmt":"2016-01-23T16:34:37","guid":{"rendered":"https:\/\/wp.okra.host\/article\/redirects-with-mod_rewrite\/"},"modified":"2021-03-07T14:48:49","modified_gmt":"2021-03-07T13:48:49","slug":"redirects-with-mod_rewrite","status":"publish","type":"ht_kb","link":"https:\/\/kb.okra.host\/de\/article\/redirects-with-mod_rewrite\/","title":{"rendered":"Umleitungen mit mod_rewrite"},"content":{"rendered":"

Overview<\/h2>\n

A redirect changes the URL, in browser, from one URL to another. A variety of redirect codes exist to force a variety of behaviors in the browser (or spider).<\/p>\n

Usage<\/h2>\n

All redirects are controlled through a .htaccess<\/a> file in the document root<\/a> of your target domain<\/a> or subdomain<\/a>. The following stanza is a common, and simple redirect if the URL is www.example.com, then redirect to example.com:<\/p>\n

RewriteEngine On\r\nRewriteBase \/\r\nRewriteCond %{HTTP_HOST} ^www.example.com$\r\nRewriteRule ^(.*)$ http:\/\/example.com\/$1 [R,L]<\/pre>\n
Likewise, a converse rule to redirect example.com to www.example.com would be a minor alteration of RewriteCond<\/code> and RewriteRule<\/code>:<\/p>\n
RewriteEngine On\r\nRewriteBase \/\r\nRewriteCond %{HTTP_HOST} ^example.com$\r\nRewriteRule ^(.*)$ http:\/\/www.example.com\/$1 [R,L]<\/pre>\n
Notice the difference? RewriteCond stands for “rewrite condition” and RewriteRule “rewrite rule”. That is to say, if this condition<\/em> matches, apply this rule<\/em>, which consists of a regular expression substitution, to the current URL. Rewrites operate using\u00a0regular expressions<\/a>, in particular Perl-compatible (“PCRE”)<\/a>.<\/p>\n
Required components<\/h2>\n
A redirect always<\/strong><\/em> requires two crucial components:<\/p>\n
RewriteEngine On\r\nRewriteBase \/<\/pre>\n
RewriteEngine On<\/code> enables URL rewriting. RewriteBase \/<\/code> anchors all rules to the current directory. [su_highlight]RewriteBase is absolutely necessary when used with addon domains and subdomains.[\/su_highlight]<\/p>\n
The following examples will omit these 2 lines for brevity:<\/p>\n
Examples<\/h3>\n
Redirect to SSL<\/h4>\n
RewriteCond %{HTTPS} !^on$\r\nRewriteRule ^(.*)$ https:\/\/%{HTTP_HOST}\/$1 [R,L]<\/pre>\n
Discussion:<\/strong><\/span>\u00a0look for an environment variable called HTTPS<\/code>. Whenever SSL is used, this variable is set by the web server. If no flag is set, assume normal HTTP traffic. Redirect to SSL (https) and keep the hostname (%{HTTP_HOST}<\/code>) + URL path ($1<\/code>, captured from left-side)<\/p>\n
Redirect codes<\/h3>\n
An optional number may be added onto a R flag to specify a\u00a0redirect code. By default a 302 is sent in a redirect response. The following redirect codes may be used by changing R<\/code> to R=XXX<\/code>, where XXX is one of the following codes:<\/p>\n
[su_table]<\/p>\n\n\n\n\n\n\n\n\n\n
Code<\/strong><\/th>\nName<\/strong><\/th>\nDescription<\/strong><\/th>\n<\/tr>\n<\/thead>\n
301<\/td>\nMoved Permanently<\/td>\nResource is no longer accessible under URL, use new URL<\/td>\n<\/tr>\n
302<\/td>\nFound<\/td>\nURL resides temporarily under new resource, continue to use this URL<\/td>\n<\/tr>\n
303<\/td>\nSee Other<\/td>\nResponse resides elsewhere and should be retrieved using a GET; used mostly with POST requests<\/td>\n<\/tr>\n
307<\/td>\nTemporary Redirect<\/td>\nURL resides elsewhere; new location may differ on different requests. Continue to use this URL in future.<\/td>\n<\/tr>\n
308<\/td>\nPermanent Redirect<\/td>\nSimilar to 301, works with POST, but experimental<\/a><\/em><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
[\/su_table]<\/p>\n
See also<\/h2>\n