help with bash script

[muton]

I don't know of any programs which will give me raw interface speeds, so I am trying to write a bash script. This is all so I can have speeds for my interface (wlan0) in an fvwm module. It was working a minute ago... now it's not. I changed something, don't know what. This is the script:

#!/bin/sh
  2 # this script counts the number of new bytes per second for rx and tx as seen
     by ifconfig
  3 # if you want to see it live from the console use watch -n1,
  4 # it's meant to be repeated from an FvwmScript's PeriodicTasks section
  5 i=0
  6 while [ 2 -eq 2 ] ; do
  7         ref1="$(/sbin/ifconfig wlan0)"
  8         prdct1="$(echo "$ref1" | sed --quiet -e '/RX bytes/p')"
  9         rxpre="$(echo $prdct1 | awk -F' ' '{print $2}')"
 10         txpre="$(echo $prdct1 | awk -F' ' '{print $6}')"
 11         rx="$(echo $rxpre | awk -F: '{print $2}')"
 12         tx="$(echo $txpre | awk -F: '{print $2}')"
 13         getrx() {
 14                 rx_onesecago="$rx"
 15                 sleep 1
 16                 rx_now="$rx"
 17                 currentrx="$(expr $rx_now - $rx_onesecago)"
 18                 echo "$rx_now - $rx_onesecago"
 19                 return $currentrx
 20         }
 21         gettx() {
 22                 tx_onesecago="$tx"
 23                 sleep 1
 24                 tx_now="$tx"
 25                 currenttx="$(expr $tx_now - $tx_onesecago)"
 26         }
 27         if [ $i -lt 1 ]; then
 28                 getrx &
 29                 rx_speed=$?
 30                 gettx
 31                 echo "rx: $rx_speed B/s tx: $currenttx B/s"
 32                 if [ "$1" == "full" ]; then
 33                 echo -e "rx_size_before: $rx_onesecago\ttx_size_before: $tx_
    onesecago"
 34                 echo -e "rx_size_after: $rx\ttx_size_after: $tx "
 35                 fi
 36         else
 37                 break 2
 38         fi
 39         i=$(expr $i + 1)
 40 done

I'm figuring rx_now and rx_onesecago are coming out the same because prdct1,rxpre,etc.. are not updated each time they are used. I really have no idea how it worked before.
output: (with internet radio station streaming)

rx: 0 B/s tx: 0 B/s
rx_size_before: tx_size_before: 10447727
rx_size_after: 93203253 tx_size_after: 10447727
93203253 - 93203253

[nmset]

This can be of help.

#!/bin/bash
getData() {
  ref1="$(/sbin/ifconfig eth0)"
  prdct1="$(echo "$ref1" | sed --quiet -e '/RX bytes/p')"
  rxpre="$(echo $prdct1 | awk -F' ' '{print $2}')"
  txpre="$(echo $prdct1 | awk -F' ' '{print $6}')"
  rx="$(echo $rxpre | awk -F: '{print $2}')"
  tx="$(echo $txpre | awk -F: '{print $2}')"
  [ $1 = 0 ] && echo $rx
  [ $1 = 1 ] && echo $tx
}
while [ "$1" = "15" ] ; do
  rx0=$(getData 0)
  tx0=$(getData 1)
  sleep 1
  rx1=$(getData 0)
  tx1=$(getData 1)
  echo $(($rx1-$rx0)) $(($tx1-$tx0))
done

Why should rx_onesecago and rx_now be different in

14                  rx_onesecago="$rx"
 15                 sleep 1
 16                 rx_now="$rx"

?

[muton]

thank you.
to get the increase of the rx and tx totals