First, a quick note about formatting your posts: put "<code>" and "</code>" at the beginning and end of perl code -- not including paragraphs of text (use plain old html tags like <P>, <UL>, etc to format your text). It's easy to get to Writeup Formatting Tips -- take a look at that.

Second, how about you try one more diagnostic: create a junk file (or locate such a file that already exists), and give the path/name of that file as a command line arg to this little script:

#!/usr/bin/perl

print "-M of $ARGV[0] is ".(-M $ARGV[0]).$/; # should be positive

system("touch $ARGV[0]"); # reset file's mod time to now.
sleep 1
print "-M of $ARGV[0] is now ".(-M $ARGV[0]).$/; # should be (very sma
+ll) negative

sleep 4; 
print "-M of $ARGV[0] is now ".(-M $ARGV[0]).$/; # should be equal to 
+previous
[download]

You seem to be doing the right sort of test (-M>0), so it could still be one of those cases where you really believe that you're checking the right file (the same one that the 3rd party thing created), and that the file is new, etc, when in fact...

update: fixed link

print "minus M returns: ", (-M $logfile), "\n";

#!/usr/bin/perl

use strict;
use warnings;

my $logfile = "file.log";
my $internal = 0;
if ($internal)
{
    # create a logfile
    open LOGFILE, ">$logfile" or die "can't open $logfile: $!";
    print LOGFILE "This is a test\n";
    close LOGFILE or die "can't close $logfile: $!";
}
else
{
    # create logfile externally
    system("./write-log");
}

# sleep?
sleep 3;

print "minus M returns: ", (-M $logfile), "\n";
# test modification time
if (-M $logfile > 0)
{
    print "The logfile generated by 3rd party script is not new\n";
    exit(1);
}
else
{
    print "It's a new logfile! Hoooray!\n";
}

__END__
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Hi Beable
   I ran it a couple of times, These are the values I got:
 # Using $mtime = (-M $logfile);

 MTIME: 1.15740740740741e-05
 MTIME: 0.000104166666666667

Thanks for your reply.
bayruds
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Hi Bayruds, here is a program to find out how old the log file actually is. It turns out that we are talking about 1 to 9 seconds old. Is that too old for you? If that seems like a reasonable age, I'd suggest you change your "-M" test line to something like:

# see if the file is more than about one hour old
if (-M $logfile > 0.042) { ... }
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Here's the program. Somebody will probably produce a one-liner to do this now.

#!/usr/bin/perl

use strict;
use warnings;

my $secs_per_day = 60 * 60 * 24;
while (my $line = <DATA>)
{
    chomp $line;
    if ($line =~ m/MTIME:\s+(.*)/)
    {
        my $time = $1;
        my $secs = $time * $secs_per_day;
        print "$time days is $secs second(s)\n";
    }
}

__END__

Output:
1.15740740740741e-05 days is 1 second(s)
0.000104166666666667 days is 9.00000000000003 second(s)


__DATA__
MTIME: 1.15740740740741e-05
MTIME: 0.000104166666666667
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