gdb --args /u01/mysql/bin/mysqld
#--------------------------------------------------------------------------------
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-90.el6)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /u01/mysql/bin/mysqld...done.
(gdb) b mysqld_main   # 设置断点
Breakpoint 1 at 0x58c0e4: file /u01/mysql-5.6.35/sql/mysqld.cc, line 5245.
(gdb) r   # 运行
Starting program: /u01/mysql/bin/mysqld 
[Thread debugging using libthread_db enabled]

Breakpoint 1, mysqld_main (argc=1, argv=0x7fffffffe668) at /u01/mysql-5.6.35/sql/mysqld.cc:5245
5245    {
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.192.el6.x86_64 keyutils-libs-1.4-5.0.1.el6.x86_64 
krb5-libs-1.10.3-57.el6.x86_64 libcom_err-1.42.8-1.0.2.el6.x86_64 libgcc-4.4.7-17.el6.x86_64 
libselinux-2.0.94-7.el6.x86_64  libstdc++-4.4.7-17.el6.x86_64 nss-softokn-freebl-3.14.3-23.el6_7.x86_64 
openssl-1.0.1e-48.el6.x86_64 zlib-1.2.3-29.el6.x86_64
(gdb) n   # 向下
5250      my_progname= argv[0];
(gdb) n
5254      if (my_init())                 // init my_sys library & pthreads
(gdb) s   # 看源码位置
my_init () at /u01/mysql-5.6.35/mysys/my_init.c:69
69        if (my_init_done)
(gdb) n
74        my_umask= 0660;                       /* Default umask for new files */
(gdb) n
75        my_umask_dir= 0700;                   /* Default umask for new directories */
#--------------------------------------------------------------------------------

{
  /*
    Perform basic thread library and malloc initialization,
    to be able to read defaults files and parse options.
  */
  my_progname= argv[0];