what did you try, show the iterations ?

Try something like

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

## use File::Spec; our $thisf = File::Spec->rel2abs( __FILE__ );
use Path::Tiny qw/ path /; 
our $thisfile = path( __FILE__ )->realpath;
    
Main( @ARGV );
exit( 0 );

sub Main {
    my( $command, @args ) = @_;
    my %commands = ( 
        deleteafter => \&DeleteAfter, 
        indexpage => \&IndexPage,
        servefile => \&ServeFile,
    );
    my $action = $commands{lc $command} || \&IndexPage;
    $action->( @args );
}

sub IndexPage {
    require CGI;
    my( $q ) = CGI->new;
    if( my $temporaryfile = AllowedTemporaryFile( $q ) ){
        BackgroundDeleteAfter( $temporaryfile, $seconds );
        return ServeFile( $q, $temporaryfile );
    }
    
    return ListFiles( $q );
}


sub DeleteAfter {
    my $time = shift;
    close STDIN;
    close STDOUT;
## close STDERR; open STDERR ...;
    sleep $time;
    unlink($_) for @_;
}

sub BackgroundDeleteAfter {
    require Proc::Background;
    Proc::Background->new( 
        $^X, 
        $thisfile, 
        deleteafter => @_
    );
}

sub AllowedTemporaryFile { ... }
sub ListFiles { ... }
sub ServeFile {
    my( $q, $file ) = @_;
    ## see [id://1151407]
}
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