scandir

SCANDIR(3)		  Linux Programmer’s Manual		   SCANDIR(3)



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

SYNOPSIS
       #include <dirent.h>

       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);

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(), sorted	 using	qsort()	 with
       the  comparison	function  compar(),  and  collected in array namelist
       which is allocated via malloc().	 If filter is NULL, all	 entries  are
       selected.

       The alphasort() and versionsort() functions can be used as the compar-
       ison 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.  LSB has deprecated	 the  library
       call alphasort() and never contained scandir().

       The  functions  scandir()  and  alphasort() are from BSD 4.3, and have
       been available under Linux since libc4.	Libc4 and libc5 use the	 more
       precise 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
       strcmp(3).

EXAMPLE
       /* 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);
	   }
       }

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



GNU				  2001-12-26			   SCANDIR(3)