SCANDIR(3)		   Linux Programmers Manual		   SCANDIR(3)



NAME
       scandir, alphasort, versionsort - scan a directory for matching entries

SYNOPSIS
       #include 

       int scandir(const char *dir, struct dirent ***namelist,
	      int (*filter)(const struct dirent *),
	      int (*compar)(const struct dirent **, const struct dirent **));

       int alphasort(const void *a, const void *b);

       int versionsort(const void *a, const void *b);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       scandir(), alphasort(): _BSD_SOURCE || _SVID_SOURCE
       versionsort(): _GNU_SOURCE

DESCRIPTION
       The scandir() function scans the directory  dir,  calling  filter()  on
       each  directory entry.  Entries for which filter() returns non-zero are
       stored in strings allocated via malloc(3), sorted using	qsort(3)  with
       the comparison function compar(), and collected in array namelist which
       is allocated via  malloc(3).   If  filter  is  NULL,  all  entries  are
       selected.

       The alphasort() and versionsort() functions can be used as the compari
       son function compar().  The former sorts directory entries  using  str
       coll(3), the latter using strverscmp(3) on the strings (*a)->d_name and
       (*b)->d_name.

RETURN VALUE
       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  consid
       ered  to  be respectively less than, equal to, or greater than the sec
       ond.

ERRORS
       ENOMEM Insufficient memory to complete the operation.

CONFORMING TO
       None of these functions is in POSIX.1-2001, but alphasort()  and  scan
       dir() are under consideration for a future revision to POSIX.1.

       The  functions scandir() and alphasort() are from 4.3BSD, and have been
       available under Linux since libc4.  Libc4 and libc5 use the  more  pre
       cise prototype

	   int alphasort(const struct dirent ** a,
			 const struct dirent **b);

       but glibc 2.0 returns to the imprecise BSD prototype.

       The  function  versionsort()  is a GNU extension, available since glibc
       2.1.

       Since glibc 2.1, alphasort() calls strcoll(3);  earlier	it  used  str
       cmp(3).

EXAMPLE
       #define _SVID_SOURCE
       /* print files in current directory in reverse order */
       #include 

       int
       main(void)
       {
	   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);
	   }
       }

SEE ALSO
       closedir(3),    fnmatch(3),   opendir(3),   readdir(3),	 rewinddir(3),
       seekdir(3), strcmp(3), strcoll(3), strverscmp(3), telldir(3)

COLOPHON
       This page is part of release 3.05 of the Linux  man-pages  project.   A
       description  of	the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.



GNU				  2007-07-26			    SCANDIR(3)