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



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  com‐
       par().   The  former  sorts  directory  entries using strcoll(3), the latter using strver‐
       scmp(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 direc‐
       tory 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 rel‐
       ative 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.

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).

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), str‐
       coll(3), strverscmp(3), telldir(3)

COLOPHON
       This  page  is  part of release 3.74 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/.



GNU                                         2014-05-28                                 SCANDIR(3)


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