写脚本的时候，经常需要用到超时控制。看《shell专家编程》时看到一个好例：修改了一下，

1.超过timeout时间还没执行完，则kill进程，发邮件告警:

set-x
mailSend()
{
        mailContent="xxxx Web response time over 5 seconds"
        echo $mailContent | mail -s "xxxxxx Web TimeOut"xxxxx@xxx.cion
}
timeout()
{
        waitfor=3
        command=$*
        $command &
        commandpid=$!

        ( sleep $waitfor ; kill -9 $commandpid  >/dev/null2>&1&& mailSend )&

        watchdog=$!
        sleeppid=$PPID
        wait $commandpid >/dev/null2>&1

        kill $sleeppid >/dev/null2>&1
}

#测试的函数

test123()
{
        sleep 20
}

timeout test123

2.超过timeout时间还没执行完，只发邮件告警，程序正常执行:

mailSend()
{
        mailContent="xxxxe Web response time over 5 seconds,Please have a check !"
        echo $mailContent | mail -s "xxxxx WEB response time over 5 senconds" $mailTo
}
timeout()
{
        waitfor=6
        command=$*
        $command &
        commandpid=$!

        ( sleep $waitfor ;  mailSend )&

        watchdog=$!
        sleeppid=$PPID
        wait $commandpid >/dev/null2>&1
        kill  -9 $watchdog >/dev/null2>&1
        kill $sleeppid >/dev/null2>&1
}