gdb commands

list:
        #list symbols
        (gdb)list


debug multi-process:
        http://www.ibm.com/developerworks/cn/linux/l-cn-gdbmp/index.html
        set follow-fork-mode
        show follow-fork-mode
        http://www.delorie.com/gnu/docs/gdb/gdb_26.html
        set detach-on-fork [on|off]
where

print
        file::variable
        function::variable
        #print x in file f2.c
        (gdb) p 'f2.c'::x