Because I am craving for this for months; Because I only found kilometres-long texts about use, performance, advanced manipulation… but no simple thing at all; Because I like (useful) lists. Here is...
- Because I am craving for this for months;
- Because I only found kilometres-long texts about use, performance, advanced manipulation… but no simple thing at all;
- Because I like (useful) lists.
Here is a short summary of various redirect rules and their uses.
Redirect
- (1)
Redirect, RedirectTemp, Redirect temporary or Redirect 302 - URL 1 is redirected to URL 2; it is visible in the address bar[1].
- (2)
RedirectPermanent or RedirectPermanent or Redirect 301 - Same as (1), but permanent[2].
- (3)
Redirect Seeother or Redirect 303 - Temporary change, do not change the index. Seldom used.
- (4)
Redirect Gone or Redirect 410 - The page has disappeared and nothing will replace it. Think of it as a « voluntary 404″.
- (5)
Redirect xxx - Redirect with the corresponding code.
- (6)
RedirectMatch - Same as (1), but with regular expressions[3].
- (7)
RedirectMatch Permanent - Same as both (2) and (6)[4].
Notice how (6) and (7) differ from the other: they do not just send a code, they change the behaviour of the syntax. Consequenty, it is not possible (
AFAIK) to use regexps with other than 301.
Rewrite
Rewrite is different and not necessarily better. But in any case, it is more complex (and I won’t delve into it for now). The main differences between
Redirect and
Rewrite are:
Redirect uses mod_alias; Rewrite uses mod_rewrite — except for old Apache version, where both rules use mod_rewrite. Big deal.Rewrite hides the redirection to the user — this means the address stays the same in the address bar. That is the main difference between Redirect and Rewrite.Rewrite is the only one able to cope with dynamic URL (you know, those damn question marks in QUERY STRING). Not even RedirectMatch can do it (AFAIK).
Redirect is appropriate when you want people to remember the new address; You may be sure they will copy the good address and that will save you some
CPU cycles in non redirecting anymore. On the contrary,
Rewrite is appropriate when you want the address to stay the same/not to be visible; A good example is hiding the architecture (/wordpress/, /wiki/…). Ultimately, using one or the other is not a technical consideration but more of a human and strategic one.
Examples
Below are examples I use to change
domain.tld/images/foo to
domain.tld/dotclear/public/images/foo (I actually only use the fourth one). The leading circumflex (
^) is for forcing the matching string to be at the begining of the address.
Redirect ^/images/(.*)$ http://blog.empyree.orghttp://david.latapie.name/wordpress/wp-content/uploads/$1RedirectPermanent ^/images/(.*)$ http://blog.empyree.orghttp://david.latapie.name/wordpress/wp-content/uploads/$1RedirectMatch ^/images/(.*)$ http://blog.empyree.orghttp://david.latapie.name/wordpress/wp-content/uploads/$1RedirectMatch Permanent ^/images/(.*)$ http://blog.empyree.orghttp://david.latapie.name/wordpress/wp-content/uploads/$1
To be completely accurate, I must say that Rewrite is able to do most, if not all, of what Redirect may do, thank to the
flags. But that would be another topic I prefer not to speak of here.
- Which is a good idea in some contexts; Error code 302.
- Error code 301; search engine should update their index (but Google does not).
- Don’t use it if you don’t need it: regexp parsing requires CPU cycles, even when there is no actual regexp to parse.
- That is, the resulting regexp-powered redirections are permanent (error code 301).
Ils en parlent mais ne me le disent pas, les petits cachottiers :
