Use Shell in Linux to monitor network traffic, and use linuxshell

Use Shell in Linux to monitor network traffic, and use linuxshell

#input the network name if [ -n "$1" ]; then    eth_name=$1else    eth_name="eth0"fi send_o=`ifconfig $eth_name | grep bytes | awk '{print $6}' | awk -F : '{print $2}'`recv_o=`ifconfig $eth_name | grep bytes | awk '{print $2}' | awk -F : '{print $2}'` send_n=$send_orecv_n=$recv_o i=0while [ $i -le 100000 ]; do    send_l=$send_n    recv_l=$recv_n    sleep 2    send_n=`ifconfig $eth_name | grep bytes | awk '{print $6}' | awk -F : '{print $2}'`    recv_n=`ifconfig $eth_name | grep bytes | awk '{print $2}' | awk -F : '{print $2}'`    i=`expr $i + 1`     send_r=`expr $send_n - $send_l`    recv_r=`expr $recv_n - $recv_l`    total_r=`expr $send_r + $recv_r`    send_ra=`expr \( $send_n - $send_o \) / $i`    recv_ra=`expr \( $recv_n - $recv_o \) / $i`    total_ra=`expr $send_ra + $recv_ra`    sendn=`ifconfig $eth_name | grep bytes | awk -F \( '{print $3}' | awk -F \) '{print $1}'`    recvn=`ifconfig $eth_name | grep bytes | awk -F \( '{print $2}' | awk -F \) '{print $1}'`    clear    echo "Last second : Send rate: $send_r Bytes/sec Recv rate: $recv_r Bytes/sec Total rate: $total_r Bytes/sec"    echo "Average value: Send rate: $send_ra Bytes/sec Recv rate: $recv_ra Bytes/sec Total rate: $total_ra Bytes/sec"    echo "Total traffic after startup: Send traffic: $sendn Recv traffic: $recvn"done

The following common shell commands are used:
Whether the variable string is null
To run a command, you must use the application as the command.
Basic Writing of while LOOP
Use of some mathematical expressions
Escape Writing of some special characters output