my $pager= $ENV{PAGER} || "more";
open STDOUT, "| $pager"
  or  warn "Not paging STDOUT: $!\n";

##</code><code>##

perl -le "open STDOUT, '| more'; $|=1; print for 0..50; close(STDOUT) or warn $!; wait"
...
Bad file descriptor at -e line 1.
...

##</code><code>##

END { close(STDOUT) }