This part,

my $output = <STDOUT>; 
print STDOUT "$input";
[download]

is not right. You are trying to read from the output! And print goes by default to STDOUT which in this case is the terminal.

You need to open a file handle for output like this:

open OUT, '>', 'c:/users/lastgen/docs/saved_ppid' 
        or die "unable to open out file $!";       
print OUT "something";
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Note that I used "forward slash" instead of "back slash" in the path name. This is completely fine on Windows and will save yourself a lot of pain because "\" means something very special in Perl.

Update: If c:/users/lastgen/docs/saved_ppid is a directory then of course you need a target file like: c:/users/lastgen/docs/saved_ppid/ppid.txt. I see stevieb posted while I was typing. That code shows the preferred way for a file handle, using a lexical variable ($wfh) instead of what I did, a bare word (OUT). I did it that way because it might be easier for you to get started with and look at bit more obvious.