.htaccess中RewriteRule的替换对象：是整个URL路径还是正则匹配部分？

Great question—this is one of the most common stumbling blocks when learning Apache's Rewrite Module, so let's break this down clearly with your example.

Core Rule to Remember #

The Substitution in a RewriteRule replaces only the portion of the URL path that your regular expression Pattern matches—not the entire path, unless your pattern explicitly targets the full path.

Breakdown of Your Exact Scenario #

Your configuration is:

RewriteRule ^test new

Here's what happens when you visit http://example.com/test/file.php:

1. Apache strips the hostname http://example.com/, leaving the path test/file.php to evaluate against the rule.
2. The pattern ^test is a regex where ^ means "start of the string". This pattern matches the leading test characters in the path test/file.php—it does NOT match the entire path.
3. The substitution new replaces exactly the matched portion (test), while the unmatched part of the path (/file.php) is preserved automatically.

The final resulting path will be new/file.php.

Contrast with Exact Match for Clarity #

To highlight how pattern scope changes behavior, if you used a rule that matches the full path:

RewriteRule ^test$ new

Here, the $ means "end of the string", so this rule only triggers when the path is exactly test (i.e., visiting http://example.com/test). In this case, the entire path is matched, so the substitution replaces the whole thing, resulting in just new.

Key Takeaways #

• What gets replaced depends entirely on your regex pattern:
  • If your pattern matches a segment of the path, only that segment is replaced.
  • If your pattern matches the full path (using anchors like ^ and $ with appropriate wildcards), the entire path is replaced.
• Always test your regex patterns to confirm exactly what they're matching—this avoids unexpected substitution behavior.

内容的提问来源于stack exchange，提问作者Franky