[root@gw /]# uname -a
Linux gw 2.4.22 #8 SMP Wed Sep 24 13:53:53 EDT 2003 i686 i686 i386 GNU/Linux
[root@gw /]# perl -v

This is perl, v5.8.0 built for i386-linux-thread-multi

Copyright 1987-2002, Larry Wall

[root@gw /]# cat test
#!/usr/bin/perl

$file = "/proc/net/snmp";
$ABC = 0;

while ( $i ne 0 ) {
  &GET;
  $RATE = $FIELDS[3] - $ABC;
  $ABC = "$FIELDS[3]";
  print "$RATE\n";
}

sub GET {
  open (FILE, $file);
  @LINES = <FILE>;
  close (FILE);
  $LINE = $LINES[1];
  @FIELDS = split(/ /, $LINE);
  sleep 1;
}