普通的前pression死循环 [英] Regular expression endless loop

问题描述

我在这台服务器，其中两个域的名称指向。所以在我的.htaccess文件我想作一个简单的规则说沿线的东西：

I have this server where two domain-names are pointed to. So in my .htaccess-file I want to make a simple rule that says something along the line:

如果你来自test.domain.com然后去夹X，如果你来自the-other-sub.domain.com然后去夹Y.这意味着我移动子域之一，所以我可以喜欢做它，所以它重定向到正确的网址（在人们关注的一个深层链接的情况下。例如，如果有人去 http://test.domain.com/path/to /一/页，他们将被重定向到 /路径/到/一/页在新的文件夹中。

If you come from test.domain.com then go to folder X, if you come from the-other-sub.domain.com then go to folder Y. And this means that I'm moving one of the subdomains, so I could like to make it so it redirects to the right URL (in case that people are following a deep link. For instance if people go to http://test.domain.com/path/to/a/page that they will be redirected to /path/to/a/page in the new folder.

我挣扎这样做，虽然。我不明白的是，为什么是这code：

I'm struggling to do so, though. What I don't get is, why is that this code:

Options +FollowSymLinks
RewriteEngine on

RewriteBase /
RewriteCond %{HTTP_HOST} ^subdomain.domain.com$ 
RewriteRule ^(.*)$ /test/$1 [L,R=301]

叶我，所以如果我去 subdomain.domain.com/abc ，那么浏览器就会送我去 subdomain.domain.com /测试/检验/检验/检验/检验/检验/检验/检验/检验/检测/测试/ ABC
然后抱怨，我有和无限循环。并请没有智能链接到Apache的文档mod_rewrite.c ......我读过它，这是它采取了我。我知道，*意味着匹配0次以上，但我不明白为什么副本的目标串一遍又一遍又一遍......？ /测试/ 不是在常规的前pression一个变量，是吗？那么，为什么它重复一次吗？

Leaves me, so if I go to subdomain.domain.com/abc , then the browser will send me to subdomain.domain.com/test/test/test/test/test/test/test/test/test/test/test/abc and then complaining about that I have and endless loop. And please no smart links to Apache's documentation for mod_rewrite.c... I've read it, and this is where it has taken me. I know that the * means 'match 0 or more times', but I don't get why that copies the destination-string over and over and over...? /test/ isn't a variable in the regular expression, is it? So why does it repeat it?

推荐答案

如果您无条件地重定向到 /测试/...那么它将继续增加 /测试/ 之前重定向的URL也。

If you redirect unconditionally to /test/... then it will keep adding /test/ before redirected URLs also.

要解决使用这样的规则：

To fix use this rule:

Options +FollowSymLinks
RewriteEngine on

RewriteBase /
RewriteCond %{HTTP_HOST} ^subdomain\.domain\.com$ [NC]
RewriteRule ^((?!test/).*)$ /test/$1 [L,R=301,NC]

（？！测试/）是指添加 /测试/ 只有当它已经没有按负先行条件T开始 /测试/ 。

(?!test/) is negative lookahead condition which means add /test/ only if it already doesn't start with /test/.

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