crontab 定时任务守护程序，停止服务器时出现 job for * canceled

（1）首先要在程序启动的时候加入定时任务到crontab

#! /bin/sh
mkdir -p /home/apps/components/ams/ 2>/dev/null
cp ./amswatchdog.sh /home/apps/components/ams/
CRONTAB_CMD="* * * * * sh /home/apps/components/ams/amswatchdog.sh
* * * * * sleep 10;sh /home/apps/components/ams/amswatchdog.sh
* * * * * sleep 20;sh /home/apps/components/ams/amswatchdog.sh
* * * * * sleep 30;sh /home/apps/components/ams/amswatchdog.sh
* * * * * sleep 40;sh /home/apps/components/ams/amswatchdog.sh
* * * * * sleep 50;sh /home/apps/components/ams/amswatchdog.sh"
(crontab -l 2>/dev/null | grep -Fv /home/apps/components/ams/amswatchdog.sh; echo "$CRONTAB_CMD") | crontab -

（2）停止服务器时，要清除crontab中的定时任务，并重新加载定时任务，重启crontab服务器

#! /bin/sh
(crontab -l 2>/dev/null | grep -Fv /home/apps/components/ams/amswatchdog.sh) | crontab -

service crond reload

service crond restart

（3）还要清除正在执行的定时job，查询并杀死正在执行的amswatchdog.sh进程，否则会出现job for ** canceled的错误，导致服务停止不了；

ps -ef | grep amswatchdog.sh | grep -v grep | awk '{print $2}' |xargs kill -9