@在位置塊（命名位置）中是什麼意思？

在NGINX配置中，location塊內的@符號用於定義命名位置，這些是僅限內部使用的端點，不能直接由客戶端請求匹配，它們通常通過error_page、try_files或rewrite指令調用。 1. 命名位置以@開頭，如location @notfound，不會響應直接請求，而是從配置其他部分觸發；2. 常用於自定義錯誤處理、內部路由和後端代理回退；3. 例如，結合try_files實現靜態文件不存在時轉發到@backend；4. 注意事項包括：不可直接訪問、避免命名衝突、使用描述性名稱。命名位置可包含標準NGINX指令，支持變量，其作用類似於代碼中的函數或子程序，本身不執行操作，但在被引用時發揮功能。

In NGINX configuration, the @ symbol inside a location block is used to define a named location . These are internal-only endpoints that can't be matched by client requests directly—they're meant to be called using the error_page , try_files , or rewrite directives.

Named locations are handy for handling things like custom error pages, internal redirects, or processing fallback logic without exposing those paths publicly.

How Named Locations Work

A named location starts with @ followed by a name:

 location @notfound {
    # internal logic here
}

This location won't respond to direct requests like /notfound . Instead, it's triggered from other parts of the config—commonly via error_page or as a fallback in try_files .

For example:

 error_page 404 @notfound;

location @notfound {
    return 404 "Custom not found message";
}

When a 404 happens, NGINX internally forwards the request to the @notfound named location.

Common Use Cases for @-Named Locations

Here are a few real-world scenarios where named locations shine:

• Custom error handling : Redirecting 404s or 500s to a consistent internal handler.
• Internal routing : Using try_files to fall back to an internal location if files aren't found.
• Backend proxy fallbacks : If static files don't exist, pass control to a backend service.

Example with try_files :

 location / {
    try_files $uri $uri/ @backend;
}

location @backend {
    proxy_pass http://myapp;
}

In this case:

• NGINX first tries to serve a static file.
• If it doesn't exist, it routes the request to the @backend named location.

Things to Keep in Mind When Using @

• They're internal only : You can't access them directly via a browser or API call.
• Avoid naming conflicts : Choose unique names to prevent unexpected behavior.
• Use descriptive names : Like @php , @fallback , or @api_error , so it's clear what they do.

Also, remember that:

• You can use variables inside named locations.
• They can include any standard NGINX directives like proxy_pass , return , or rewrite .

So, when you see @something inside a location block, it's just NGINX setting up a label for internal routing—very similar to a function or subroutine in code. It doesn't do anything on its own but becomes powerful when referenced elsewhere.

基本上就這些。

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