Annotate text input to expand epoch timestamps to normal time.

epochfilter.pl

#!/usr/bin/env perl
use strict;

sub tag {
    my $epoch = shift;
    return "$epoch=<".(scalar (localtime $epoch)).">";
}

sub tag_line {
    my $line = shift;
    $line =~ /^(.*?)(\d{9,})(.*)$/; 
    my $tagged = $1;
    $tagged .= tag($2) if $2;
    $tagged .= tag_line($3) if $3;
    return $tagged;
}

while (my $line = <>) {
    print tag_line($line);
}