1. Print a http header (at least a Content-Type header)
2. open the file (check for errors!)
3. Read from the file (with the $variable = <$filehandle>; syntax) and print its content
4. close the file

Update: Op updated the post, so I'll do that as well ;) Step 3 involves a small computation then. And probably chomp to remove the newline from the string before treating it as a number.

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

my $q = CGI->new();
print $q->header;

my $other_value = 42;

open(my $fh, '<', 'input.file') or die "Unable to open 'input.file' fo
+r reading: $!";
while (<$fh>) {
    s/^\s+|\s+$/g; # strip whitespace
    $_ += $other_value;
    print "$_ ";
}
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