Isso funcionará para o formato dado. Isso pressupõe que o arquivo sempre comece com 00: 00: 00: 00.
#!/usr/bin/env perl
use strict;
use warnings;
open(my $infh, '<', 'ABC_TabDelim.txt') or die $!;
my $outfh;
my $filecount = 0;
while ( my $line = <$infh> ) {
if ( $line =~ /^00:00:00:00/ ) {
close($outfh) if $outfh;
open($outfh, '>', sprintf('ABC%02d_TabDelim.txt', ++$filecount)) or die $!;
}
print {$outfh} $line or die "Failed to write to file: $!";
}
close($outfh);
close($infh);