Error: 'debugserver' is not a valid command

怎么回事来着 帮我看看哪里出了问题。
(lldb) br s -a ‘0x0000000000017000’
Breakpoint 1: where = AppStore`AppStore[0x00004000], address = 0x00017000
(lldb) debugserver -x backboard *:1234 /Applications/WeChat.app/WeChat
error: ‘debugserver’ is not a valid command.

debugserver是在iOS上输的