#!/usr/bin/perl -w
use strict;

while ((my $line=<STDIN>) !~ /^\s*$/)
{
   print $line;
}

# to stop on quit use this:
while ((my $line=<STDIN>) !~ /^\s*q(uit)?\s*$/i)
{
}

#use of comma operator
#note paren's are needed around print to get 
#line buffering to work out right.

while ((print "enterline:"), (my $line=<STDIN>) !~ /^\s*$/)
{
   print $line;
}