实现原理：通过每秒读取一次/proc/net/dev动态文件，计算得出平局速度。执行格式

    1. sh ./speedmonitor.sh eth0

    脚本详情：

    1. #!/bin/bash
    3. ethn=$1
    5. while true; do
    6.     RX_pre=$(cat /proc/net/dev | grep $ethn | sed 's/:/ /g' | awk '{print $2}')
    7.     TX_pre=$(cat /proc/net/dev | grep $ethn | sed 's/:/ /g' | awk '{print $10}')
    8.     sleep 1
    9.     RX_next=$(cat /proc/net/dev | grep $ethn | sed 's/:/ /g' | awk '{print $2}')
    10.     TX_next=$(cat /proc/net/dev | grep $ethn | sed 's/:/ /g' | awk '{print $10}')
    12.     clear
    13.     echo -e "\t RX $(date +%k:%M:%S) TX"
    15.     RX=$((${RX_next} - ${RX_pre}))
    16.     TX=$((${TX_next} - ${TX_pre}))
    18.     if [[ $RX -lt 1024 ]]; then
    19.         RX="${RX}B/s"
    20.     elif [[ $RX -gt 1048576 ]]; then
    21.         RX=$(echo $RX | awk '{print $1/1048576 "MB/s"}')
    22.     else
    23.         RX=$(echo $RX | awk '{print $1/1024 "KB/s"}')
    24.     fi
    26.     if [[ $TX -lt 1024 ]]; then
    27.         TX="${TX}B/s"
    28.     elif [[ $TX -gt 1048576 ]]; then
    29.         TX=$(echo $TX | awk '{print $1/1048576 "MB/s"}')
    30.     else
    31.         TX=$(echo $TX | awk '{print $1/1024 "KB/s"}')
    32.     fi
    34.     echo -e "$ethn \t $RX $TX "
    36. done