> For the complete documentation index, see [llms.txt](https://docshome.gitbook.io/nginx-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docshome.gitbook.io/nginx-docs/readme/tiao-shi-ri-zhi.md).

# 调试日志

* [为指定客户端做调试日志](https://docshome.gitbook.io/nginx-docs/readme/pages/-M6a1v7oGUefMtwgQ4s5#为指定客户端做调试日志)
* [记录日志到循环内存缓冲区](https://docshome.gitbook.io/nginx-docs/readme/pages/-M6a1v7oGUefMtwgQ4s5#记录日志到循环内存缓冲区)

要开启调试日志，需要在编译 Nignx 时增加如下配置：

```bash
./configure --with-debug ...
```

之后应该使用 [error\_log](http://nginx.org/en/docs/ngx_core_module.html#error_log) 指令设置调试级别：

```
error_log /path/to/log debug;
```

要验证 nginx 是否已经配置为支持调试功能，请运行 `nginx -V` 命令：

```bash
configure arguments: --with-debug ...
```

预构建 [Linux](http://nginx.org/en/linux_packages.html) 包为 nginx-debug 二进制文件的调试日志提供了开箱即用的支持，可以使用命令运行。

```bash
service nginx stop
service nginx-debug start
```

之后设置 `debug` 级别。Windows 的 nginx 在编译时就已经支持调试日志，因此只需设置 `debug` 级别即可。

请注意，重新定义日志而不指定 `debug` 级别将禁止调试日志。在下面的示例中，重新定义 `server` 上的日志级别，nginx 将不会在此服务器上做日志调试。

```
error_log /path/to/log debug;

http {
    server {
        error_log /path/to/log;
        ...
```

为了避免这种情况，重新定义日志级别应该被注释掉，或者明确指定日志为 `debug` 级别。

```
error_log /path/to/log debug;

http {
    server {
        error_log /path/to/log debug;
        ...
```

## 为指定客户端做调试日志

也可以仅为选定的客户端地址启用调试日志：

```
error_log /path/to/log;

events {
    debug_connection 192.168.1.1;
    debug_connection 192.168.10.0/24;
}
```

## 记录日志到循环内存缓冲区

调试日志可以被写入到循环内存缓冲区中：

```
error_log memory:32m debug;
```

在 `debug` 级别将日志写入到内存缓冲区中，即使在高负载情况下也不会对性能产生重大的影响。在这种情况下，可以使用如下 `gdb` 脚本来提取日志：

```bash
set $log = ngx_cycle->log

while $log->writer != ngx_log_memory_writer
    set $log = $log->next
end

set $buf = (ngx_log_memory_buf_t *) $log->wdata
dump binary memory debug_log.txt $buf->start $buf->end
```

## 原文档

* <http://nginx.org/en/docs/debugging_log.html>


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