I think this will do what you want.

use strict;
open (INFILE, "<infile") or die "could not open file";
my %files;
while (<INFILE>) {
    foreach ( /(\w+\.cxx)\b/g ) {
        $files{$_}++;
    }
}
close INFILE;
open (OUTFILE, ">outfile") or die "could not open file";

foreach (sort keys %files) {
    print OUTFILE "$_\n";
}
close OUTFILE;
[download]

outfile will contain

aclpi.cxx
i95val.cxx
radiomeasurements.cxx
rlpval.cxx
[download]

Note that the order is not the same. This is due to the fact that I use a hash and the keys function does not give the keys back in any particular order, so I sort them. If you want to do the build-ing in perl then you can do something like this

foreach (sort keys %files) {
    system "build", $_;
}
[download]

--

flounder