shell参数 传递

$# 是传给脚本的参数个数

$0 是脚本本身的名字

$1 是传递给该shell脚本的第一个参数

$2 是传递给该shell脚本的第二个参数

$@ 是传给脚本的所有参数的列表

$* 是以一个单字符串显示所有向脚本传递的参数，与位置变量不同，参数可超过9个

$$ 是脚本运行的当前进程ID号

$? 是显示最后命令的退出状态，0表示没有错误，其他表示有错误

区别：@*

• 相同点：都是引用所有参数
• 不同点：只有在双引号中体现出来。假设在脚本运行时写了三个参数（分别存储在12 3）则"*" 等价于 “12 3"（传递了一个参数）；而“@" 等价于 "1""2" "$3"（传递了三个参数）

一个守护脚本 demon：

###################
#  VERSION=0.0.4
###################

#!/bin/bash
###############################
####Global parameters##########
###############################

set -x #echo on

CUR_DIR=`pwd`
VA_LOG_LEVEL="err"
VA_RUN_LEVEL="demon"

####for record file delete
DEFAULT_DAYS=15
RECORD_FILE_PATH=/var/video_record
DEFAULT_FILE_CHECK=1
##### unit : G
DEFAULT_MINI_SPACE=15
PROCESS_NUM=2
#CertMS
#DarwinStreamingServer

#CertMS_Server
#Darwin_Server


#functions
###################
##parse argument
###################
usage()
{
  echo "######################################"

  echo "usage of maintain.sh :"
  echo "options  "
  echo "-l  : videomon log level [warn , info , err] , default is err"
  echo "-m  : videomon run mod[demon , foreground] , default is demon"
  echo "-c   : record file delete check! [ 0:not check 1:check , default is 1]"
  echo "-n   : [Delete the record files of the n days ago , default is 15 days]"
  echo "-d   : [record file path , default is :/var/video_record]"
  echo "For example: ./maintain.sh -l info -m foreground -c 1 -n 10 -d /video_record or ./maintain.sh "
  echo "-?  : usage info"
  
  echo "######################################"
}

get_opt()
{
  while getopts ":?l:m:c:n:d:" optname
  do
    case "$optname" in
    "l")
      VA_LOG_LEVEL=$OPTARG
      ;;
    "m")
      VA_RUN_LEVEL=$OPTARG
      ;;
    "c")
      DEFAULT_FILE_CHECK=$OPTARG
      ;;
    "n")
      DEFAULT_DAYS=$OPTARG
      ;;
    "d")
      RECORD_FILE_PATH=$OPTARG
      ;;
    "?")
      usage
      exit 0
      ;;
    *)
      # Should not occur
      echo "maintain.sh :Unknown error while processing options"
      exit 0
      ;;
    esac
done
}

####################
##Video_Monitor clean
####################
video_monitor_clean()
{
    for (( i = 0 ; $i < PROCESS_NUM; i++ ));
    do
        echo $i;
        pid_videomon=`ps aux|grep -v grep|grep  "videomon$i" | grep "$"|sed -n '1P'|awk '{print $2}'`

        if [ $pid_videomon ]
        then
            killall -9 videomon$i
        fi
    done
}

####################
##ran_videomon_monitor
####################
ran_videomon_monitor()
{
    echo $1 
  cd $CUR_DIR/bin$1

  if [ $VA_RUN_LEVEL == "demon" ]
  then
    nohup ./videomon$1 -l $VA_LOG_LEVEL -p pid -d &
  else
    nohup ./videomon$1 -l $VA_LOG_LEVEL -p pid &
  fi

  echo Start videomon Success!
}


####################
##record file check
####################
record_file_check()
{
  cd $CUR_DIR
  if [ -f record_file_delete.sh ]
  then
    chmod +x record_file_delete.sh
    ###
    pid_record_sh=`ps aux|grep -v grep|grep  "record_file_delete.sh" | grep "$"|sed -n '1P'|awk '{print $2}'`
    if [ -z $pid_record_sh ]
    then
      nohup ./record_file_delete.sh -n $DEFAULT_DAYS -d $RECORD_FILE_PATH -s $DEFAULT_MINI_SPACE &
    else
      echo "record_file_delete.sh is running!"
    fi
    ###
  else
    echo "Can not find record_file_delete.sh"
    return 0
  fi
}

####################
##videomon_maintain
####################

videomon_maintain()
{
  while true
  do
    sleep 2

    ####Check whether need to delete record files
    if [ $DEFAULT_FILE_CHECK -eq 1 ]
    then
      record_file_check
    fi

    for (( i = 0 ; $i < PROCESS_NUM; i++ ));
    do
        echo $i; 
        pid=`ps aux|grep -v grep|grep  "videomon$i -l $VA_LOG_LEVEL" | grep "$"|sed -n '1P'|awk '{print $2}'`
        if [ -z $pid ]
        then
              ran_videomon_monitor $i
        fi
    done
  done
}

###############
##start process
###############
get_opt $@
if [ $? != 0 ]
then 
  echo get_opt unknow options!
  exit 1
fi

video_monitor_clean

for (( i = 0 ; $i < PROCESS_NUM; i++ ));
do
    ran_videomon_monitor $i
done

videomon_maintain

参考http://www.cnblogs.com/kaituorensheng/p/4002697.html