在Shell脚本中使用Trap捕获相关信号进行hook

from http://steve-parker.org/sh/trap.shtml

trap指令可以用来捕获相关信号，并运行指定的代码

例如

#!/bin/sh

trap cleanup EXIT

#or

#trap cleanup 0

cleanup()

{

#do some cleanup thing when exit

#...

}

或者

trap handle_interrupt 2

handle_interrupt()

{

#do sth when ctrl_c is pressed

#...

}

下面是一些常见信号的数值

0	0	On exit from shell
1	SIGHUP	Clean tidyup
2	SIGINT	Interrupt
3	SIGQUIT	Quit
6	SIGABRT	Abort
9	SIGKILL	Die Now (cannot be trap'ped)
14	SIGALRM	Alarm Clock
15	SIGTERM	Terminate