> Is there a way to identify when the output is being presented in a separate window (such that I could change the code so that the "Enter to close window:" prompt only appears in these cases)?

Yes you can, and the solotion was already at pm: Re: Re: Re: Parent process name but is slow because it processes all PIDs to get one matching $$ (I wonder if this can be shortened..) using the cpan Win32::Process::Info module.

Here an adapted solution:

use strict;
use Win32::Process::Info;

my $pihandle = Win32::Process::Info->new();
my @procinfo = $pihandle->GetProcInfo();

my $ParentPID;
my %ProcNames;

foreach my $PIDInfo (@procinfo) {
    $ProcNames{$PIDInfo->{ProcessId}} = $PIDInfo->{Name};

    if ($PIDInfo->{ProcessId} == $$) {
        $ParentPID = $PIDInfo->{ParentProcessId};
        last;
    }
}

print "Parent's name is [", $ProcNames{$ParentPID}, "]\n";


if ( $ProcNames{$ParentPID} eq 'OpenWith.exe' or $ProcNames{$ParentPID
+} eq 'explorer.exe') {
    print 'Press ENTER to close the window: ';
    <>;
}
else{ print "..exiting normally\n"; }
[download]

Calling the above program from command line (I always use the longhish form: perl program.pl because I do not want to mess with assoc and friends and .pl is associated just with the editor ;) the program exit directly:

Discipulus@works:D>perl parentpid01.pl

Parent's name is [cmd.exe]
..exiting normally
[download]

But right clicking the file and using Open with and browsing to the current perl.exe I get:

Parent's name is [explorer.exe]
Press ENTER to close the window:
[download]

Weirdly (well nothing is normal on this OS) the first time I got that the program was called by OpenWith.exe but once perl.exe is in the cached list of Open With.. the caller became explorer.exe which I suppose is the same if you double click it and you have its extension associated to perl.exe

L*