NAME

       scandir, scandirat, 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 struct dirent **a, const struct dirent **b);

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

       #include <fcntl.h>          /* Definition of AT_* constants */
       #include <dirent.h>

       int scandirat(int dirfd, const char *dirp, struct dirent ***namelist,
              int (*filter)(const struct dirent *),
              int (*compar)(const struct dirent **, const struct dirent **));

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

       scandir(), alphasort():
           _BSD_SOURCE || _SVID_SOURCE
           || /* Since glibc 2.10: */
               (_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)

       versionsort(): _GNU_SOURCE

       scandirat(): _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.

   scandirat()
       The scandirat() function operates in exactly the same  way  as  scandir(),  except  for  the  differences
       described here.

       If  the  pathname given in dirp is relative, then it is interpreted relative to the directory referred to
       by the file descriptor dirfd (rather than relative to  the  current  working  directory  of  the  calling
       process, as is done by scandir() for a relative pathname).

       If  dirp  is  relative  and dirfd is the special value AT_FDCWD, then dirp is interpreted relative to the
       current working directory of the calling process (like scandir()).

       If dirp is absolute, then dirfd is ignored.

       See openat(2) for an explanation of the need for scandirat().

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.

       The following additional errors can occur for scandirat():

       EBADF  dirfd is not a valid file descriptor.

       ENOTDIR
              dirp is a relative path and dirfd is a file descriptor referring to a file other than a directory.

VERSIONS

       versionsort() was added to glibc in version 2.1.

       scandirat() was added to glibc in version 2.15.

ATTRIBUTES

       For an explanation of the terms used in this section, see attributes(7).

       ┌───────────────────────────┬───────────────┬────────────────┐
       │Interface                  │ Attribute     │ Value          │
       ├───────────────────────────┼───────────────┼────────────────┤
       │scandir(), scandirat()     │ Thread safety │ MT-Safe        │
       ├───────────────────────────┼───────────────┼────────────────┤
       │alphasort(), versionsort() │ Thread safety │ MT-Safe locale │
       └───────────────────────────┴───────────────┴────────────────┘

CONFORMING TO

       alphasort(), scandir(): 4.3BSD, POSIX.1-2008.

       versionsort() and scandirat() are GNU extensions.

NOTES

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

       Before glibc 2.10, the two arguments of alphasort() and versionsort() were typed as const  void *.   When
       alphasort()  was  standardized  in  POSIX.1-2008,  the argument type was specified as the type-safe const
       struct  dirent **,  and  glibc  2.10  changed  the  definition  of  alphasort()  (and   the   nonstandard
       versionsort()) to match the standard.

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),  seekdir(3),  strcmp(3),  strcoll(3),
       strverscmp(3), telldir(3)

COLOPHON

       This page is part of release 4.04 of  the  Linux  man-pages  project.   A  description  of  the  project,
       information   about   reporting   bugs,   and   the  latest  version  of  this  page,  can  be  found  at
       http://www.kernel.org/doc/man-pages/.