scandir (3)
Leading comments
Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk) %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. ...
NAME
scandir, scandirat, alphasort, versionsort - scan a directory for matching entriesSYNOPSIS
#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 (*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); } }