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



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

SYNOPSIS
       #include <&lt;dirent.h>&gt;

       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)-&gt;d_name and
       (*b)-&gt;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 <dirent.h>

       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)