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  comparison  function
       compar().   The  former  sorts  directory  entries  using  strcoll(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 considered to be respectively less than,  equal
       to, or greater than the second.

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 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

       #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), scandirat(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/.