You still seem to be under the mistaken impression that "less code" means "faster". Several of your code reductions will make the code slower. The only change that I see potentially making your code much faster is using slurping (which means the files must be fairly small). Given that, I'd do: 

#!/usr/bin/perl -w
use strict;

my $Directory= "/var/spool/mail";
my $BadDir= "bad/";
my $BadString= ("\0"x30)."\t\0\0(\0";
my $BadCount= 10;
my $ExceptionsFile= "exclude";
my $ExceptionsUpdated;
my %Exception;
my $SleepLength= 1;

chdir( $Directory )
    or  die "Can't chdir to $Directory: $!\n";
opendir DIR, "."
    or  die "Can't open directory, $Directory: $!\n";
undef $/;
while(  1  ) {
    if(  $ExceptionsUpdated != -M $ExceptionsFile  ) {
        open EXCEPT, "< $ExceptionsFile"
            or  die "Can't read $ExceptionsFile: $!\n";
        my @except= <EXCEPT>;
        close EXCEPT;
        chomp( @except );
        @Exception{@except}= (1) x @except;
    }
    rewinddir( DIR )
        or  die "Can't rewind directory, $Directory: $!\n";
    my $file;
    while(  $file= readdir(DIR)  ) {
        if(  $file =~ /^di/  &&  ! $Exception{$file}  ) {
            if(  ! open FILE, "< $file"  ) {
                warn "Can't read $file: $!\n";
                next;
            }
            my $data= <FILE>;
            close FILE;
            my $count= ()= $data =~ /\Q$BadString/g;
            next   if  $BadCount <= $count;
            if(  ! rename( $file, $BadDir.$file )  ) {
                warn "Can't rename $file to $BadDir$file: $!\n";
            } else {
                warn "Moved $file to $BadDir$file.\n";
            }
        }
    }
    sleep $SleepLength;
}

[download]

        - tye

In reply to (tye)Re2: Hitting a moving target (transient files) by tye
in thread Hitting a moving target (transient files) by Limbic~Region

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