scandir, alphasort, versionsort - scan a directory for matching entries
        #include <dirent.h>
       int scandir(const char *dir, struct dirent ***namelist,
	      int (*select)(const struct dirent *),
	      int (*compar)(const void *, const void *));
       int alphasort(const void *a, const void *b);
       int versionsort(const void *a, const void *b);
       The scandir() function scans the directory  dir,  calling  select()  on
       each  directory entry.  Entries for which select() returns non-zero are
       stored in strings allocated via malloc(), sorted using qsort() with the
       comparison  function compar(), and collected in array namelist which is
       allocated via malloc().
       The alphasort() and versionsort() functions can be used as the comparison
  function  for the scandir() function to sort the directory entries
       into alphabetical order.  Although they parameters point to void,  they
       are  in	fact  pointers	to pointers (struct dirent**) to two directory
       entries, a and b, to compare.
       alphasort() will order the files with strcoll(3),  while  versionsort()
       will use strverscmp(3).
       The scandir() function returns the number of directory entries selected
       or -1 if an error occurs.
       The alphasort() and versionsort()  functions  return  an  integer  less
       than,  equal  to, or greater than zero if the first argument is considered
 to be respectively less than, equal to, or greater than  the  second.
       ENOMEM Insufficient memory to complete the operation.
        BSD 4.3
        /* print files in current directory in reverse order */
       #include <dirent.h>
       main(){
	   struct dirent **namelist;
	   int n;
	   n = scandir(".", &namelist, 0, alphasort);
	   if (n < 0)
	       perror("scandir");
	   else {
	       while(n--) {
		   printf("%s\n", namelist[n]->d_name);
		   free(namelist[n]);
	       }
	       free(namelist);
	   }
       }
       opendir(3),    readdir(3),   closedir(3),   rewinddir(3),   telldir(3),
       seekdir(3)
GNU				  1996-04-11			    SCANDIR(3)
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