帮忙 解释一下这段脚本

chuty

#!/bin/sh

EXCUTE_NAME="racer"
X_NAME="race"

verify_system()
{
  #check if this is a linux platform, if not linux, alert and quit
  if [ `uname` != "Linux" ]; then
        echo "This process being available ONLY on Linux"
          return 1
  fi

  #check if it's root, otherwise quit
  if [ `whoami` != "root" ]; then
          echo "No more than root has previlege to run this process"
          return 1
  fi
  #check size of log file
  if [ -f "ecou.log" ]; then
        FSIZE=`du -ks ecou.log | awk '{print $1}'`
        if [ $FSIZE -gt 1000 ]; then
                >ecou.log        #clear the log file
        fi
  else
             >ecou.log
  fi
  
  return 0
}

find_ecou()
{
   #FINDNUM=`ps -ef | grep "$EXCUTE_NAME" | grep -v grep | wc -l`
   FINDNUM=`pgrep -nx "$EXCUTE_NAME" | wc -l`
   if [ $FINDNUM -eq 0 ]; then
        return 1
   else
        return 0
   fi
}

start_ecou()
{
  if find_ecou
  then
        echo "The pocess is running"
        exit
  fi

  #to which interface link with Internet
  INTERNUM=`ifconfig -a | grep "HWaddr" | wc -l`
  if [ $INTERNUM -eq 0 ]; then
        echo "No net Interface can be found, may you type command such as insmod and ifup eth0 first"
        return 1
  fi

  #if more than ONE eth installed, have to select one
  CMPNUM=0
  if [ "$INTERNUM" -gt "$CMPNUM" ]; then
        ifconfig -a | grep "HWaddr" | awk '
          BEGIN {
                i=0;
                printf("All names of your net interface installed\n");
                printf("-----------------------------------------\n");
          }
          {
                printf("\t%s\t%d\n", $1, i);
                i++;
          }'
         echo -n "Input one name to hace access with Internet (eth0): "       
         read INTERNAME
         if [ ! $INTERNAME ]; then   #default name is eth0
                INTERNAME="eth0"
         fi
         #if the name input is correct or not
         TMP_NUM=`ifconfig -a | grep "HWaddr" | grep "$INTERNAME" | wc -l`
         if [ $TMP_NUM -eq 0 ]; then
                echo "You have input an invalid name of net interface"
                return 1
         fi
  else
        INTERNAME=`ifconfig -a |grep "HWaddr" |        awk '{print $1}'`
  fi
  echo "The name of interface is: " $INTERNAME

  #okey, we have got correct env & parameters to run this process
  #However, definitly necessary ini files as well as process file must be found
  #in the same path
  if [ ! -f "racer.ini" ]; then
        echo "Warning: No relative file racer.ini found, re-creating"
        echo "Server1=218.29.0.227" >racer.ini
        echo "Server2=218.29.0.228" >>racer.ini
  fi

  if [ ! -f "$X_NAME" ]; then
        echo "Unable to find process to run, try re-install your process again!"
        return 1
  fi
         
  if [ ! -x "$X_NAME" ]; then
        chmod +x $X_NAME
  fi
  
  if [ ! -L "$EXCUTE_NAME" ]; then
        ln -s $X_NAME $EXCUTE_NAME
  fi
  
  ./$EXCUTE_NAME $INTERNAME

  RETVAL=$?
  if [ ! $RETVAL -eq 0 ]; then
        echo "Failed to run the process"
  else
        echo "$EXCUTE_NAME has been started successfully"
  fi
  
  return 0
}

#for help info
usage()
{
        echo "Usage: $0 {[start]|[status]|[stop]}"       
}

#to stop ecou
stop_ecou()
{
    #ps -ef | grep "$EXCUTE_NAME" | grep -v grep | awk '{print $2}' | xargs kill -SIGINT 2>/dev/null
    pgrep -nx "$EXCUTE_NAME" | xargs kill -SIGINT 2>/dev/null
    FINDNUM=1
    while [ ! $FINDNUM -eq 0 ]
    do
            #FINDNUM=`ps -ef | grep "$EXCUTE_NAME" | grep -v grep | wc -l`
            FINDNUM=`pgrep -nx "$EXCUTE_NAME" | wc -l`
            sleep 1
    done
    if [ $? -eq 0 ]; then
               echo "The process has been halted successfully"
    else
               echo "Failed to terminate the process OR the process is not running"
    fi
}

#to tell status
tell_status()
{
   #ps -ef | grep "$EXCUTE_NAME" | grep -v grep | awk '{print $2}' | xargs kill  -SIGUSR1 2>/dev/null
   pgrep -nx "$EXCUTE_NAME" | xargs kill  -SIGUSR1 2>/dev/null
   if [ $? -eq 0 ]; then
        return;
   else
        echo "No status returned for $EXCUTE_NAME"
   fi
}

#main
  PARAM_NUM=$#
  if [ ! $PARAM_NUM -eq 1 ]; then
    usage
    exit
  fi
  
  if [ -n $RACERC ]; then
      cd $RACERC
  fi

  if ! verify_system
  then
     exit
  fi

  case $1 in
        start)         start_ecou;;
        status) tell_status;;
        stop)         stop_ecou;;
        *)        usage;;
  esac

MMMIX

直接说你什么地方不懂吧，要是一点都不明白，先看看 shell 编程的入门资料，要不然别人解释了你可能也听不明白。