【求助】Syntax error: "(" unexpected (expecting "done")

源码：
#!/bin/bash
#network
#Mike.Xu
while : ; do
time=*date +%m"-"%d" "%k":"%M*
day=*date +%m"-"%d*
rx_before=*ifconfig eth0|sed -n "8"p|awk *{print $2}*|cut -c7-*
tx_before=*ifconfig eth0|sed -n "8"p|awk *{print $6}*|cut -c7-*
sleep 2
rx_after=*ifconfig eth0|sed -n "8"p|awk *{print $2}*|cut -c7-*
tx_after=*ifconfig eth0|sed -n "8"p|awk *{print $6}*|cut -c7-*
rx_result=$[(rx_after-rx_before)/256]
tx_result=$[(tx_after-tx_before)/256]
echo "$time Now_In_Speed: "$rx_result"kbps Now_OUt_Speed: "$tx_result"kbps"
sleep 2
done