5.1.7 Breakpoint Command Lists
可以在任何断点（或者是监测点watchpoint，或者是捕获点catchpoint）生效时，执行一串命令。例如：或许想在某一点处，打印特定变量的值，或者是打开另外一个断点。
commands [range…]
… command-list …
end
end关键字，代表着命令集的结束。如果想删除断点关联的命令：type commands and follow it immediately with end。
如果commands 后面不带参数，就默认是最后一个断点，watchpoint或者catchpoint（(not to the breakpoint most recently encountered). If the most recent breakpoints were set with a single command, then the commands will apply to all the breakpoints set by that command. This applies to breakpoints set by rbreak, and also applies when a single break command creates multiple breakpoints (see Section 10.2 [Ambiguous Expressions], page 110).
实例
(gdb) break main
Breakpoint