my @files = ('abc*.txt','efg*.txt','xyz*.txt');

     my @a = $ftp->ls($files[0]);
     my @b = $ftp->ls($files[1]);
     my @c = $ftp->ls($files[2]);
     
     if (@a && @b && @c){
     	print "file is not missing";
     }

     else{
     	print "File X is missing";
     }