如何在ubuntu中删除一个文本文件中的某一列？

代码:

#! /bin/bash

net=$1

while true
do

tmp=`ifconfig $net|grep '接收字节'`
#echo $tmp

dspeed=${tmp/接收字节:/}
down_pre=${dspeed/ (*/}
#echo $down_pre

uspeed=${tmp/*发送字节:/}
up_pre=${uspeed/ (*/}
#echo $up_pre

sleep 1

tmp=`ifconfig $net|grep '接收字节'`
#echo $tmp

dspeed=${tmp/接收字节:/}
down_next=${dspeed/ (*/}
#echo $down_next

uspeed=${tmp/*发送字节:/}
up_next=${uspeed/ (*/}
#echo $up_next

declare -i down_speed up_speed

down_speed=$((${down_next}/1024-${down_pre}/1024))
up_speed=$((${up_next}/1024-${up_pre}/1024))

clear

echo "Down-speed:$down_speed KB/s     Up-speed:$up_speed KB/s"
echo "Total-down:"$((${down_next}/1024)) "KB    Total-up:"$((${up_next}/1024)) "KB"
sleep 1
done