#accts_to_load.txt contains the filenames of al the files I want to append together
$acctstoload = "/apps/tmp/invs/accts_to_load.txt";
open(ACCTLOAD, $acctstoload) || die("cannot open $acctstoload");

#Here, I want to give a specific name to the file all the split files are being merged into
$batchfile = "mergedfile.txt";

while(<ACCTLOAD>)  {
`cat $_ >> $batchfile`;
}