Unless you've landed in a very inhospitable environment--like, say, Windows--you should be able to take advantage of the native tools. For example:

    local $SIG{PIPE} = 'IGNORE';
    open PAGER, '|'.($ENV{PAGER} || 'less')
      or die "Can't spawn pager: $!\n";
    while (something) {
        print PAGER something_else;
    }
    close PAGER;
[download]

The (temporary) assignment to $SIG{PIPE} keeps your program from dying if the pager quits early. If you're concerned about wasting time generating useless data, you may want to add this refinement:

    select PAGER;
    $| = 1;
    while (something) {
        print something_else
          or last;
    }
[download]

Remember, tool use is one of the things that make us human. :-)

UPDATE:Thanks to agoth for the bug fix. And yes, tye, I know that Windows has a "more" command. But it's so hostile that I never use it. There is a Windows port of "less", anyway.

    -- Chip Salzenberg, Free-Floating Agent of Chaos