如何在gdb中列出结构信息？

Function \"struct\" not defined.

(gdb) l ngx_http_request_t
10  
11  #include <ngx_config.h>
12  #include <ngx_core.h>
13  
14  
15  typedef struct ngx_http_request_s     ngx_http_request_t;
16  typedef struct ngx_http_upstream_s    ngx_http_upstream_t;
17  typedef struct ngx_http_cache_s       ngx_http_cache_t;
18  typedef struct ngx_http_file_cache_s  ngx_http_file_cache_t;
19  typedef struct ngx_http_log_ctx_s     ngx_http_log_ctx_t;
(gdb) l struct ngx_http_request_s
Function \"struct\" not defined.