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本文为khler原作，转载必须确保本文完整并完整保留原作者信息及本文原始链接
Author: HeYuanHui
E-mail: khler@163.com
QQ: 23381103
MSN: pragmac@hotmail.com
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如何保证服务一直运行？如何保证即使服务挂掉了也能自动重启？在写服务程序时经常会碰到这样的问题。在Linux系统中，强大的shell就可以很灵活的处理这样的事务。
下面的shell通过一个while-do循环，用ps -ef|grep 检查loader进程是否正在运行，如果没有运行，则启动，这样就保证了崩溃挂掉的进程重新被及时启动。
必须注意两点：
1、ps |grep 一个进程时必须加上其路劲，否则容易grep到错误的结果；
2、必须用 -v 从结果中去除grep命令自身，否则结果非空。
#!/bin/sh
#=====================
#YuanHui.HE
#khler@163.com
#=====================
while :
do
echo "Current DIR is " $PWD
stillRunning=$(ps -ef |grep "$PWD/loader" |grep -v "grep")
if [ "$stillRunning" ] ; then
echo "TWS service was already started by another way"
echo "Kill it and then startup by this shell, other wise this shell will loop out this message annoyingly"
kill -9 $pidof $PWD/loader
else
echo "TWS service was not started"
echo "Starting service ..."
$PWD/loader
echo "TWS service was exited!"
fi
sleep 10
done
#=====================
#YuanHui.HE
#khler@163.com
#=====================
while :
do
echo "Current DIR is " $PWD
stillRunning=$(ps -ef |grep "$PWD/loader" |grep -v "grep")
if [ "$stillRunning" ] ; then
echo "TWS service was already started by another way"
echo "Kill it and then startup by this shell, other wise this shell will loop out this message annoyingly"
kill -9 $pidof $PWD/loader
else
echo "TWS service was not started"
echo "Starting service ..."
$PWD/loader
echo "TWS service was exited!"
fi
sleep 10
done
如果启动此shell时发现进程已经存在，说明以别的方式启动了进程而不是此shell，那么它会持续提醒找到进程，解决办法是，要么只用此shell启动服务，要么一经发现以其他方式启动的服务即kill掉，上面的语句就是这么干的：
kill -9 $pidof $PWD/loader
