统计TCP网络连接情况

#!/bin/bash
metric=$1
tmp_file=/tmp/tcp_status.txt
/bin/netstat -an|awk '/^tcp/{++S[$NF]}END{for(a in S) print a,S[a]}' > $tmp_file
case $metric in
   closed)
          output=$(awk '/CLOSED/{print $2}' $tmp_file)
          if [ "$output" == "" ];then
             echo 0
          else
             echo $output
          fi
        ;;
   listen)
          output=$(awk '/LISTEN/{print $2}' $tmp_file)
          if [ "$output" == "" ];then
             echo 0
          else
             echo $output
          fi
        ;;
   synrecv)
          output=$(awk '/SYN_RECV/{print $2}' $tmp_file)
          if [ "$output" == "" ];then
             echo 0
          else
             echo $output
          fi
        ;;
   synsent)
          output=$(awk '/SYN_SENT/{print $2}' $tmp_file)
          if [ "$output" == "" ];then
             echo 0
          else
             echo $output
          fi
        ;;
   established)
          output=$(awk '/ESTABLISHED/{print $2}' $tmp_file)
          if [ "$output" == "" ];then
             echo 0
          else
             echo $output
          fi
        ;;
   timewait)
         output=$(awk '/TIME_WAIT/{print $2}' $tmp_file)
         if [ "$output" == "" ];then
            echo 0
         else
            echo $output
         fi
       ;;
esac