| .\" Copyright (C) 1993 David Metcalfe (david@prism.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| .\" manual page may be incorrect or out-of-date.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 (faith@cs.unc.edu) |
| .\" Modified Thu Apr 11 17:11:33 1996 by Andries Brouwer (aeb@cwi.nl): |
| .\" Corrected type of compar routines, as suggested by |
| .\" Miguel Barreiro (enano@avalon.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. |
| .\" |
| .TH SCANDIR 3 2007-07-26 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| scandir, alphasort, versionsort \- scan a directory for matching entries |
| .SH SYNOPSIS |
| .nf |
| .B #include <dirent.h> |
| .sp |
| .BI "int scandir(const char *" dir ", struct dirent ***" namelist , |
| .RS |
| .BI "int (*" filter ")(const struct dirent *)," |
| .BI "int (*" compar ")(const struct dirent **, const struct dirent **));" |
| .RE |
| .sp |
| .BI "int alphasort(const void *" a ", const void *" b ); |
| .sp |
| .BI "int versionsort(const void *" a ", const void *" b ); |
| .fi |
| .sp |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .sp |
| .BR scandir (), |
| .BR alphasort (): |
| _BSD_SOURCE || _SVID_SOURCE |
| .br |
| .BR versionsort (): |
| _GNU_SOURCE |
| .SH DESCRIPTION |
| The |
| .BR scandir () |
| function scans the directory \fIdir\fP, calling |
| \fIfilter\fP() on each directory entry. |
| Entries for which |
| \fIfilter\fP() returns non-zero are stored in strings allocated via |
| .BR malloc (3), |
| sorted using |
| .BR qsort (3) |
| with the comparison |
| function \fIcompar\fP(), and collected in array \fInamelist\fP |
| which is allocated via |
| .BR malloc (3). |
| If \fIfilter\fP is NULL, all entries are selected. |
| .LP |
| The |
| .BR alphasort () |
| and |
| .BR versionsort () |
| functions can be used as the comparison function |
| .IR compar (). |
| The former sorts directory entries using |
| .BR strcoll (3), |
| the latter using |
| .BR strverscmp (3) |
| on the strings \fI(*a)\->d_name\fP and \fI(*b)\->d_name\fP. |
| .SH "RETURN VALUE" |
| The |
| .BR scandir () |
| function returns the number of directory entries |
| selected or \-1 if an error occurs. |
| .PP |
| The |
| .BR alphasort () |
| and |
| .BR 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. |
| .SH ERRORS |
| .TP |
| .B ENOMEM |
| Insufficient memory to complete the operation. |
| .SH "CONFORMING TO" |
| None of these functions is in POSIX.1-2001, but |
| .BR alphasort () |
| and |
| .BR scandir () |
| are under consideration for a future revision to POSIX.1. |
| .LP |
| The functions |
| .BR scandir () |
| and |
| .BR alphasort () |
| are from 4.3BSD, and have been available under Linux since libc4. |
| Libc4 and libc5 use the more precise prototype |
| .sp |
| .nf |
| int alphasort(const struct dirent ** a, |
| const struct dirent **b); |
| .fi |
| .sp |
| but glibc 2.0 returns to the imprecise BSD prototype. |
| .LP |
| The function |
| .BR versionsort () |
| is a GNU extension, available since glibc 2.1. |
| .LP |
| Since glibc 2.1, |
| .BR alphasort () |
| calls |
| .BR strcoll (3); |
| earlier it used |
| .BR strcmp (3). |
| .SH EXAMPLE |
| .nf |
| #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\en", namelist[n]\->d_name); |
| free(namelist[n]); |
| } |
| free(namelist); |
| } |
| } |
| .fi |
| .SH "SEE ALSO" |
| .BR closedir (3), |
| .BR fnmatch (3), |
| .BR opendir (3), |
| .BR readdir (3), |
| .BR rewinddir (3), |
| .BR seekdir (3), |
| .BR strcmp (3), |
| .BR strcoll (3), |
| .BR strverscmp (3), |
| .BR telldir (3) |