while (<DATA>)
{
  if (condition1..condition2)
  {
    # Here only the line from the moment condition1 is true, until condition2 is reached are processed
  }
}

##</code><code>##

while (<DATA>)
{
   next unless 3..7; # ignore all lines except between 3 and 7 included
   print;
}
__DATA__
One
Two
Three
Four
Five
Six
Seven
Eight
Nine