gdb -nx -batch -readnever

 -nx Do not execute commands found in any initialization files，即不执行任何初始化文件中的命令，如.gdbinit

-batch  Run in batch mode.执行完所有的命令后自动退出返回0，若出现有命令执行错误，返回非0

-readnever Do not read each symbol file’s symbolic debug information. 不读取符号信息，为了执行速度。特别是这种场景：One use of this is when a user simply wants to do the following sequence: attach, dump core, detach. Loading the debugging information in this case is an unnecessary cause of delay. 这个用法即上篇提到的：

        const char *argv[] = {"gdb", "-nx", "-batch", "-readnever",
                            "-ex", "set pagination off",
                            "-ex", "set height 0",
                            "-ex", "set width 0",
                            "-ex", attach,
                            "-ex", gcore,
                            "-ex", "detach", 
                            "-ex", "quit",
                            nullptr};