我想用gdb调试nginx程序，但是过程中出现了问题，能不能帮忙看看？

操作流程

1.首先配置了make的-g参数,使cc -g
2.gdb objs/nginx 开始调试
3.b src/core/nginx.c:91 打断点到函数的第一行，肯定有argc的

问题

1.有时候断点失效，捉摸不透，感觉自己用了假的gdb，比如输入r命令，直接执行完成了，并没有中断，使用print var，说

(gdb) print argc
No symbol "argc" in current context.

2.list参数显示文件源码，但是显示的是这个：

(gdb) list
1    /* Startup code compliant to the ELF x86-64 ABI.
2       Copyright (C) 2001-2012 Free Software Foundation, Inc.
3       This file is part of the GNU C Library.
4       Contributed by Andreas Jaeger <aj@suse.de>, 2001.
5
6       The GNU C Library is free software; you can redistribute it and/or
7       modify it under the terms of the GNU Lesser General Public
8       License as published by the Free Software Foundation; either
9       version 2.1 of the License, or (at your option) any later version.
10
(gdb) list main
No line number known for main.

按照网上配置了directory,还是不能解决，我是使用

(gdb) directory src/core/