Name
scandir, alphasort, versionsort — scan a directory for matching entries
Synopsis
#include <dirent.h>
int
scandir( |
const char * | dir, |
| struct dirent *** | namelist, | |
| int | (*filter)(const struct
dirent *), |
|
| int | (*compar)(const struct
dirent **, const struct dirent
**)); |
int
alphasort( |
const void * | a, |
| const void * | b); |
int
versionsort( |
const void * | a, |
| const void * | b); |
![[Note]](../stylesheet/note.png) |
Note | ||||
|---|---|---|---|---|---|
|
DESCRIPTION
The scandir() function scans
the directory dir,
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.
RETURN VALUE
The scandir() function
returns the number of directory entries selected or −1
if an error occurs.
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.
CONFORMING TO
None of these functions is in POSIX.1-2001, but
alphasort() and scandir() are under consideration for a
future revision to POSIX.1.
The functions scandir() and
alphasort() are from 4.3BSD,
and have been available under Linux since libc4. Libc4 and
libc5 use the more precise prototype
int alphasort(const struct dirent ** a,
const struct dirent **b);
but glibc 2.0 returns to the imprecise BSD prototype.
The function versionsort()
is a GNU extension, available since glibc 2.1.
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, 0, 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), strcoll(3), strverscmp(3), telldir(3)
COLOPHON
This page is part of release 2.79 of the Linux man-pages project. A
description of the project, and information about reporting
bugs, can be found at
http://www.kernel.org/doc/man-pages/.
|
Copyright (C) 1993 David Metcalfe (davidprism.demon.co.uk) 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. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. References consulted: Linux libc source code Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) 386BSD man pages Modified Sat Jul 24 18:26:16 1993 by Rik Faith (faithcs.unc.edu) Modified Thu Apr 11 17:11:33 1996 by Andries Brouwer (aebcwi.nl): Corrected type of compar routines, as suggested by Miguel Barreiro (enanoavalon.yaix.es). Added example. Modified Sun Sep 24 20:15:46 2000 by aeb, following Petter Reinholdtsen. Modified 2001-12-26 by aeb, following Joey. Added versionsort. |