#!/bin/sh

if [ $1 ]
then
  OUTSIGNAL="$1SIGNAL"
  OUTNOISE="$1NOISE"
  OUTSNR="$1SNR"
  i=1
  echo "Processing\c"
  while [ $i -le 20 ]
  do
    SIGNAL=$(iwconfig eth1 | grep 'Signal level' | \\
    sed 's/.*[\:=]\([0-9]*\).*[\:=]\(-*[0-9]*\).*[\:=]\(-*[0-9]*\).*/\2/')

    NOISE=$(iwconfig eth1 | grep 'Noise level' | \\
    sed 's/.*[\:=]\([0-9]*\).*[\:=]\(-*[0-9]*\).*[\:=]\(-*[0-9]*\).*/\3/')

    SNR= $(expr $SIGNAL - $NOISE)

    echo $SIGNAL >> $OUTSIGNAL
    echo $NOISE >> $OUTNOISE
    echo $SNR >> $OUTSNR

    echo ".\c"
    sleep 3s
    i='expr $i + 1'
  done
  echo "\nCompleted!"
else
  echo "ERROR: Output file not entered!"
  exit 1
fi