Nice idea++ Though I think that calculating and re-calculating an MD5 until you get a match might be rather expensive.

A cheaper alternative would be to append the length of the file: filename.ext.123456. That way, a simple -s of the file will tell if it has been fully transferred.

That would make the monitoring script very simple. All that would be needed is something like:

#! perl -slw
use strict;

my $sharePath = '...';
while( 1 ) {
    for( glob $sharePath . "IN/*" ) {
        my( $filename, $expected ) = m[/([^/]+)\.(\d+)$];
        if( $expected == -s ) {
            rename $_, "$sharePath/$filename";
            system 1, 
qq[theProcessingScript.pl <$sharePath/$filename  >$sharePath/OUT/$file
+name];
        }
    }
    sleep 1;
}
[download]