print timing & log line by line

bsdscript-timing.pl

#!/usr/bin/perl -w
# https://unix.stackexchange.com/questions/27282/how-to-use-scriptreplay
use strict;
$|=1;
open (TIMING, shift)
        or die "cannot read timing info: $!";
open (TYPESCRIPT, shift || 'typescript')
        or die "cannot read typescript: $!";
my $divisor=shift || 1;
my $start_sec=shift || 0;
my $end_sec=shift;
# Read starting timestamp line and ignore.
<TYPESCRIPT>;
my $printing = ($start_sec > 0 ? 0 : 1);
my $elapsed = 0;
my $block;
my $oldblock='';
while (<TIMING>) {
        my ($delay, $blocksize)=split ' ', $_, 2;
        # if ($printing && ($delay / $divisor > 0.0001)) {
        #         select(undef, undef, undef, $delay / $divisor - 0.0001);
        # }
        read(TYPESCRIPT, $block, $blocksize) or die "read failure: $!";
        print "\n$elapsed\n$oldblock" if ($printing);                                                                                                                                                                                  

        $elapsed += $delay;
        exit if ((defined $end_sec) && ($elapsed > $end_sec));
        $printing = ($elapsed > $start_sec);
        $oldblock=$block;
}