安装完后gdb一般会有提示：
==> gdb
gdb requires special privileges to access Mach ports.
You will need to codesign the binary. For instructions, see:
https://sourceware.org/gdb/wiki/BuildingOnDarwin
On 10.12 (Sierra) or later with SIP, you need to run this:
echo "set startup-with-shell off" >> ~/.gdbinit
安装完gdb后应该代码签名。
然后在 10.12 (Sierra) or later with SIP（系统集成保护），需要：
:echo "set startup-with-shell off" >> ~/.gdbinit