|
NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | VERSIONS | ATTRIBUTES | CONFORMING TO | NOTES | EXAMPLES | 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 5.10 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 2020-06-09 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)
Copyright and license for this manual page
|
HTML rendering created 2020-12-21 by Michael Kerrisk, author of The Linux Programming Interface, maintainer of the Linux man-pages project. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|