sh 确保同时只能运行一个sh实例

fsh=`ps ax` # don't include |grep may sure ps don't include sub shell:因为管道命令会产生子shell,会让处理麻烦.分步执行防止此问题

if [ "$UID" -ne 0 ];then
    echo "this sh must run on root"
    exit 0
fi

shPid=" $$ " #本sh pid
echo "sh pid $shPid"
shName=`basename $0`
fsh=`echo "$fsh" | grep "[0-9]\+ /.*/bash .*/sh/$shName"` #过滤进程,只保留本sh路径的进程信息,但是本过滤使用绝对路径,所以,如果非绝对路径调用时,本过滤将会失效
echo $fsh
fsh="none      `echo  $fsh` " # at the front add space,and replace /r/n,移除换行
fsh=${fsh/$shPid/$shName} # 把本sh 的pid移除,确保下面匹配过程不会得到本进程
echo "$fsh"
fsh=`expr "$fsh" : ".* \([0-9]\+\) "` #匹配是否有其它实例
echo $fsh

if [ -n "$fsh" ];then
    echo "another sh runing exit self"
    exit 0
fi