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NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | EXAMPLE | SEE ALSO | COLOPHON |
SCANDIR(3) Linux Programmer's Manual SCANDIR(3)
scandir, scandirat, alphasort, versionsort - scan a directory for
matching entries
#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():
/* Since glibc 2.10: */ _POSIX_C_SOURCE >= 200809L
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
versionsort(): _GNU_SOURCE
scandirat(): _GNU_SOURCE
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().
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.
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.
versionsort() was added to glibc in version 2.1.
scandirat() was added to glibc in version 2.15.
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 │
└───────────────────────────┴───────────────┴────────────────┘
alphasort(), scandir(): 4.3BSD, POSIX.1-2008.
versionsort() and scandirat() are GNU extensions.
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.
The program below prints a list of the files in the current directory
in reverse order.
Program source
#define _DEFAULT_SOURCE
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
int
main(void)
{
struct dirent **namelist;
int n;
n = scandir(".", &namelist, NULL, alphasort);
if (n == -1) {
perror("scandir");
exit(EXIT_FAILURE);
}
while (n--) {
printf("%s\n", namelist[n]->d_name);
free(namelist[n]);
}
free(namelist);
exit(EXIT_SUCCESS);
}
closedir(3), fnmatch(3), opendir(3), readdir(3), rewinddir(3),
seekdir(3), strcmp(3), strcoll(3), strverscmp(3), telldir(3)
This page is part of release 4.12 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
https://www.kernel.org/doc/man-pages/.
GNU 2017-03-13 SCANDIR(3)
Pages that refer to this page: open(2), closedir(3), dirfd(3), fnmatch(3), opendir(3), qsort(3), readdir(3), rewinddir(3), seekdir(3), strverscmp(3), telldir(3)