Many posters have problems debugging their RewriteRule and RewriteCond statements within their .htaccess files. Most of these are using a shared hosting service and therefore don't have access to the root server configuration. They cannot avoid using .htaccess files for rewriting and cannot enable a RewriteLogLevel" as many respondents suggest. Also there are many .htaccess-specific pitfalls and constraints are aren't covered well. Setting up a local test LAMP stack involves too much of a learning curve for most.
所以我的问题是我们建议他们如何自己调试他们的规则。以下是我的一些建议。其他建议将不胜感激。
Understand that the mod_rewrite engine cycles through .htaccess files. The engine runs this loop:
do
execute server and vhost rewrites (in the Apache Virtual Host Config)
find the lowest "Per Dir" .htaccess file on the file path with rewrites enabled
if found(.htaccess)
execute .htaccess rewrites (in the user's directory)
while rewrite occurred
So your rules will get executed repeatedly and if you change the URI path then it may end up executing other .htaccessfiles if they exist. So make sure that you terminate this loop, if necessary by adding extra RewriteCond to stop rules firing. Also delete any lower level .htaccess rewrite rulesets unless explicitly intent to use multi-level rulesets.
Make sure that the syntax of each Regexp is correct by testing against a set of test patterns to make sure that is a valid syntax and does what you intend with a fully range of test URIs. See answer below for more details.
Build up your rules incrementally in a test directory. You can make use of the "execute the deepest .htaccess file on the path feature" to set up a separate test directory (tree) and debug rulesets here without screwing up your main rules and stopping your site working. You have to add them one at a time because this is the only way to localise failures to individual rules.
Use a dummy script stub to dump out server and environment variables. (See Listing 2)If your app uses, say, blog/index.php then you can copy this into test/blog/index.php and use it to test out your blog rules in the test subdirectory. You can also use environment variables to make sure that the rewrite engine in interpreting substitution strings correctly, e.g.
RewriteRule ^(.*) - [E=TEST0:%{DOCUMENT_ROOT}/blog/html_cache/$1.html]
and look for these REDIRECT_* variables in the phpinfo dump. BTW, I used this one and discovered on my site that I had to use %{ENV:DOCUMENT_ROOT_REAL} instead. In the case of redirector looping REDIRECT_REDIRECT_* variables list the previous pass. Etc..
Make sure that you don't get bitten by your browser caching incorrect 301 redirects. See answer below. My thanks to Ulrich Palha for this.
The rewrite engine seems sensitive to cascaded rules within an .htaccess context, (that is where a RewriteRule results in a substitution and this falls though to further rules), as I found bugs with internal sub-requests (1), and incorrect PATH_INFO processing which can often be prevents by use of the [NS], [L] and [PT] flags.
还有什么评论或建议吗?
清单1——phpinfo
<?php phpinfo(INFO_ENVIRONMENT|INFO_VARIABLES);
我在调试我的mod_rewrite问题时发现了这个问题，它肯定有一些有用的建议。但最后最重要的事情是确保你的正则表达式语法正确。由于我自己的RE语法存在问题，安装regexpCheck.php脚本不是一个可行的选择。
但是由于Apache使用与perl兼容的正则表达式(PCRE)，任何有助于编写PCRE的工具都应该有帮助。我曾经在Java和Javascript REs中使用过RegexPlanet的工具，并且很高兴地发现它们也支持Perl。
只需输入正则表达式和一个或多个示例URL，它就会告诉你正则表达式是否匹配(“~=”列中的“1”)，如果适用，任何匹配组(“split”列中的数字将对应于Apache期望的数字，例如$1，$2等)。他们声称PCRE支持是“测试版”，但这正是我解决语法问题所需要的。
http://www.regexplanet.com/advanced/perl/index.html
我本可以简单地在已有的答案上添加一条评论，但我的声誉还没有达到那个水平。希望这能帮助到一些人。
下面是一些关于测试规则的额外技巧，可以简化共享主机上用户的调试
1. 使用伪用户代理
在测试一个新规则时，添加一个条件，以只使用一个伪用户代理执行它，您将在请求中使用这个假用户代理。这样就不会影响到你网站上的其他人。
e.g
#protect with a fake user agent
RewriteCond %{HTTP_USER_AGENT} ^my-fake-user-agent$
#Here is the actual rule I am testing
RewriteCond %{HTTP_HOST} !^www\.domain\.com$ [NC]
RewriteRule ^ http://www.domain.com%{REQUEST_URI} [L,R=302]
如果您正在使用Firefox，您可以使用用户代理切换器来创建假用户代理字符串并进行测试。
2. 在测试完成之前不要使用301
我见过很多帖子，人们仍然在测试他们的规则，他们使用的是301。不喜欢。
如果你没有在你的网站上使用建议1，那么不仅是你，而且当时访问你网站的任何人都将受到301的影响。
请记住，它们是永久的，并被浏览器积极缓存。
在确定之前，先用302，然后再换成301。
3.请记住，301缓存在您的浏览器中
如果您的规则不起作用，并且看起来对您来说是正确的，并且您没有使用建议1和2，那么在清除浏览器缓存后或在私人浏览时重新测试。
4. 使用HTTP捕获工具
使用Fiddler之类的HTTP捕获工具来查看浏览器和服务器之间的实际HTTP流量。
虽然其他人可能会说您的网站看起来不正确，但您可以看到并报告所有的图像、css和js都返回404错误，从而迅速缩小问题范围。
虽然其他人会报告说你从URL A开始，结束于URL C，你将能够看到他们从URL A开始，被302重定向到URL B和301重定向到URL C。即使URL C是最终目标，你也会知道这对SEO是不利的，需要修复。
您将能够看到在服务器端设置的缓存头，重放请求，修改请求头以测试....
确保每个Regexp的语法是正确的
通过对一组测试模式进行测试，以确保语法有效，并对所有测试uri执行您想要的操作。
See regexpCheck.php below for a simple script that you can add to a private/test directory in your site to help you do this. I've kept this brief rather than pretty. Just past this into a file regexpCheck.php in a test directory to use it on your website. This will help you build up any regexp and test it against a list of test cases as you do so. I am using the PHP PCRE engine here, but having had a look at the Apache source, this is basically identical to the one used in Apache. There are many HowTos and tutorials which provide templates and can help you build your regexp skills.
清单1——regexpCheck.php
<html><head><title>Regexp checker</title></head><body>
<?php
$a_pattern= isset($_POST['pattern']) ? $_POST['pattern'] : "";
$a_ntests = isset($_POST['ntests']) ? $_POST['ntests'] : 1;
$a_test = isset($_POST['test']) ? $_POST['test'] : array();
$res = array(); $maxM=-1;
foreach($a_test as $t ){
$rtn = @preg_match('#'.$a_pattern.'#',$t,$m);
if($rtn == 1){
$maxM=max($maxM,count($m));
$res[]=array_merge( array('matched'), $m );
} else {
$res[]=array(($rtn === FALSE ? 'invalid' : 'non-matched'));
}
}
?> <p> </p>
<form method="post" action="<?php echo $_SERVER['SCRIPT_NAME'];?>">
<label for="pl">Regexp Pattern: </label>
<input id="p" name="pattern" size="50" value="<?php echo htmlentities($a_pattern,ENT_QUOTES,"UTF-8");;?>" />
<label for="n"> Number of test vectors: </label>
<input id="n" name="ntests" size="3" value="<?php echo $a_ntests;?>"/>
<input type="submit" name="go" value="OK"/><hr/><p> </p>
<table><thead><tr><td><b>Test Vector</b></td><td> <b>Result</b></td>
<?php
for ( $i=0; $i<$maxM; $i++ ) echo "<td> <b>\$$i</b></td>";
echo "</tr><tbody>\n";
for( $i=0; $i<$a_ntests; $i++ ){
echo '<tr><td> <input name="test[]" value="',
htmlentities($a_test[$i], ENT_QUOTES,"UTF-8"),'" /></td>';
foreach ($res[$i] as $v) { echo '<td> ',htmlentities($v, ENT_QUOTES,"UTF-8"),' </td>';}
echo "</tr>\n";
}
?> </table></form></body></html>
