Linux Shell Implementation Daemon Script _linux Shell

Embedded beginners, the first time to upload code. Yesterday did a UDHCPD and Udhcpc Guardian, currently only with Shell imitation writing, what method can do guardian?

#! /bin/sh
#进程名字可修改
pro_name=udhcpc
wlan=ra0 while
 
true;
 
#    get $pro_name number of processes with PS
  num= ' PS aux | grep ${pro_name} |  grep-v grep |wc-l '
#  Echo $NUM
#    less than 1, restart process
  if ["${num}"-lt "1"];then
    echo "${pro_name} was  Killed "
    ${pro_name}-I ${wlan}
#    greater than 1, kill all Processes, reboot
  elif [" ${num} "-gt" 1 "];then
    echo" more than 1 ${pro_name},killall ${pro_name} "
    killall-9 $PRO _name
    ${pro_name}-I ${wlan}
  fi
#    kill zombie Process
  num_stat= ' ps aux | grep ${pro_name} | grep T | grep-v grep | wc-l '
 
  if ["${num_stat}"-gt "0"];then
    Kil Lall-9 ${pro_name}
    ${pro_name}-I ${wlan}
  fi done
 
exit 0

The above is the entire contents of this article, I hope to be familiar with the Linux shell script to help.