open(INP, "<$file_list") or die("Error reading file");
while (<INP>) {
   my $data_file = m/(\w+)/;
   # I then call a subroutine which opens the $data_file
   # and performs some analysis on it
}

##</code><code>##


open(INP, "<$file_list") or die("Error reading file");
@lines = <INP>;
while (@lines) {
   my $data_file = m/(\w+)/;
   # I then call a subroutine which opens the $data_file
   # and performs some analysis on it
}