scandir(3) - Linux manual page (original) (raw)
scandir(3) Library Functions Manual scandir(3)
NAME top
scandir, scandirat, alphasort, versionsort - scan a directory for
matching entriesLIBRARY top
Standard C library (_libc_, _-lc_)SYNOPSIS top
**#include <dirent.h>**
**int scandir(const char *restrict** _dirp_**,**
**struct dirent *restrict** _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 *restrict** _dirp_**,**
**struct dirent *restrict** _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 <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
**versionsort**():
_GNU_SOURCE
**scandirat**():
_GNU_SOURCEDESCRIPTION top
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)](../man3/malloc.3.html), sorted
using [qsort(3)](../man3/qsort.3.html) with the comparison function _compar_(), and
collected in array _namelist_ which is allocated via [malloc(3)](../man3/malloc.3.html). 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)](../man3/strcoll.3.html), the latter using [strverscmp(3)](../man3/strverscmp.3.html) on the strings
_(*a)->dname_ and _(*b)->dname_.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)](../man2/openat.2.html) for an explanation of the need for **scandirat**().RETURN VALUE top
The **scandir**() function returns the number of directory entries
selected. On error, -1 is returned, with _[errno](../man3/errno.3.html)_ set to indicate
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 top
**EBADF** (**scandirat**()) _dirp_ is relative but _dirfd_ is neither
**AT_FDCWD** nor a valid file descriptor.
**ENOENT** The path in _dirp_ does not exist.
**ENOMEM** Insufficient memory to complete the operation.
**ENOTDIR**
The path in _dirp_ is not a directory.
**ENOTDIR**
(**scandirat**()) _dirp_ is a relative pathname and _dirfd_ is a
file descriptor referring to a file other than a
directory.ATTRIBUTES top
For an explanation of the terms used in this section, see
[attributes(7)](../man7/attributes.7.html).
┌──────────────────────────────┬───────────────┬────────────────┐
│ **Interface** │ **Attribute** │ **Value** │
├──────────────────────────────┼───────────────┼────────────────┤
│ **scandir**(), **scandirat**() │ Thread safety │ MT-Safe │
├──────────────────────────────┼───────────────┼────────────────┤
│ **alphasort**(), **versionsort**() │ Thread safety │ MT-Safe locale │
└──────────────────────────────┴───────────────┴────────────────┘STANDARDS top
**alphasort**()
**scandir**()
POSIX.1-2008.
**versionsort**()
**scandirat**()
GNU.HISTORY top
**alphasort**()
**scandir**()
4.3BSD, POSIX.1-2008.
**versionsort**()
glibc 2.1.
**scandirat**()
glibc 2.15.NOTES top
Since glibc 2.1, **alphasort**() calls [strcoll(3)](../man3/strcoll.3.html); earlier it used
[strcmp(3)](../man3/strcmp.3.html).
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.EXAMPLES top
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);
}SEE ALSO top
[closedir(3)](../man3/closedir.3.html), [fnmatch(3)](../man3/fnmatch.3.html), [opendir(3)](../man3/opendir.3.html), [readdir(3)](../man3/readdir.3.html), [rewinddir(3)](../man3/rewinddir.3.html),
[seekdir(3)](../man3/seekdir.3.html), [strcmp(3)](../man3/strcmp.3.html), [strcoll(3)](../man3/strcoll.3.html), [strverscmp(3)](../man3/strverscmp.3.html), [telldir(3)](../man3/telldir.3.html)COLOPHON top
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man-pages@man7.orgLinux man-pages 6.9.1 2024-06-15 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)