alphasort man page on ElementaryOS

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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 *dirp, 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 dirp, calling filter() on
       each directory entry.  Entries for which filter() returns  nonzero  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.  On error, -1 is returned, with errno	set  to	 indicate  the
       cause of the error.

       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
       ENOENT The path in dirp does not exist.

       ENOMEM Insufficient memory to complete the operation.

       ENOTDIR
	      The path in dirp is not a directory.

VERSIONS
       versionsort() was added to glibc in version 2.1.

CONFORMING TO
       alphasort() and scandir() are specified in POSIX.1-2008, and are widely
       available.  versionsort() is a GNU extension.

       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 <dirent.h>

       int
       main(void)
       {
	   struct dirent **namelist;
	   int n;

	   n = scandir(".", &namelist, NULL, 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), scandi‐
       rat(3), seekdir(3), strcmp(3), strcoll(3), strverscmp(3), telldir(3)

COLOPHON
       This page is part of release 3.54 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				  2013-04-19			    SCANDIR(3)
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