my $DEBUG_FILE = "log"; # Global

sub debug {
    my ($t) = @_;
    return 0 unless(defined($DEBUG_FILE));
    open my $fh, ">>",$DEBUG_FILE or return 0;
    my $prefix = "[".get_date()."][".basename($0)."](".$$."):";
    print $fh $prefix.$t."\n";
    close ($fh);
    return 1;
}

##</code><code>##

[07/10/21 17:56:57][run.pl](211653):<some info example1>
[07/10/21 17:57:57][run.pl](211653):<some info example2>
[07/10/21 17:58:57][run.pl](211653):<some info example3>
[07/10/21 17:59:57][run.pl](211653):Running operation <operation>. Progress: 57%.

##</code><code>##

[07/10/21 17:56:57][run.pl](211653):<some info example1>
[07/10/21 17:57:57][run.pl](211653):<some info example2>
[07/10/21 17:58:57][run.pl](211653):<some info example3>
[07/10/21 18:05:57][run.pl](211653):Running operation <operation>. Progress: 58%.