You could use backticks to call out to perl by simply changing your code to something like this:

$file_next = `perl -ple 'exit if \$. > 10' $file_upload`;
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(note the escaping, this would also be shell dependent. I don't think this would work on windows) but that is pretty inefficient because is involves starting another process. I would just do something simple and easy to read and maintain like this:

#
# define $file_upload, etc above this
#
open INFILE, $file_upload or die $!; # or do something more graceful
my $file_next;
for (1 .. 10) {
    $file_next .= <INFILE>;
}
close INFILE;
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--

flounder