| .\" Copyright (C) 1993 David Metcalfe (david@prism.demon.co.uk) |
| .\" |
| .\" %%%LICENSE_START(VERBATIM) |
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| .\" |
| .\" 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. |
| .\" |
| .\" The pieces on scandirat(3) were copyright and licensed as follows. |
| .\" |
| .\" Copyright (c) 2012, Mark R. Bannister <cambridge@users.sourceforge.net> |
| .\" based on text in mkfifoat.3 Copyright (c) 2006, Michael Kerrisk |
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| .\" |
| .TH SCANDIR 3 2020-06-09 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| scandir, scandirat, alphasort, versionsort \- scan |
| a directory for matching entries |
| .SH SYNOPSIS |
| .nf |
| .B #include <dirent.h> |
| .PP |
| .BI "int scandir(const char *" dirp ", struct dirent ***" namelist , |
| .RS |
| .BI "int (*" filter ")(const struct dirent *)," |
| .BI "int (*" compar ")(const struct dirent **, const struct dirent **));" |
| .RE |
| .PP |
| .BI "int alphasort(const struct dirent **" a ", const struct dirent **" b ); |
| .PP |
| .BI "int versionsort(const struct dirent **" a ", const struct dirent **" b ); |
| |
| .BR "#include <fcntl.h>" " /* Definition of AT_* constants */" |
| .B #include <dirent.h> |
| .PP |
| .fi |
| .BI "int scandirat(int " dirfd ", const char *" dirp "," |
| .BI "struct dirent ***" namelist , |
| .nf |
| .RS |
| .BI "int (*" filter ")(const struct dirent *)," |
| .BI "int (*" compar ")(const struct dirent **, const struct dirent **));" |
| .RE |
| .fi |
| .PP |
| .in -4n |
| Feature Test Macro Requirements for glibc (see |
| .BR feature_test_macros (7)): |
| .in |
| .PP |
| .BR scandir (), |
| .BR alphasort (): |
| .br |
| .RS 4 |
| .PD 0 |
| .ad b |
| /* Since glibc 2.10: */ _POSIX_C_SOURCE\ >=\ 200809L |
| || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
| .PD |
| .RE |
| .PP |
| .BR versionsort (): |
| _GNU_SOURCE |
| .PP |
| .BR scandirat (): |
| _GNU_SOURCE |
| .SH DESCRIPTION |
| The |
| .BR scandir () |
| function scans the directory \fIdirp\fP, calling |
| \fIfilter\fP() on each directory entry. |
| Entries for which |
| \fIfilter\fP() returns nonzero 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. |
| .PP |
| 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. |
| .SS scandirat() |
| The |
| .BR scandirat () |
| function operates in exactly the same way as |
| .BR scandir (), |
| except for the differences described here. |
| .PP |
| If the pathname given in |
| .I dirp |
| is relative, then it is interpreted relative to the directory |
| referred to by the file descriptor |
| .I dirfd |
| (rather than relative to the current working directory of |
| the calling process, as is done by |
| .BR scandir () |
| for a relative pathname). |
| .PP |
| If |
| .I dirp |
| is relative and |
| .I dirfd |
| is the special value |
| .BR AT_FDCWD , |
| then |
| .I dirp |
| is interpreted relative to the current working |
| directory of the calling process (like |
| .BR scandir ()). |
| .PP |
| If |
| .I dirp |
| is absolute, then |
| .I dirfd |
| is ignored. |
| .PP |
| See |
| .BR openat (2) |
| for an explanation of the need for |
| .BR scandirat (). |
| .SH RETURN VALUE |
| The |
| .BR scandir () |
| function returns the number of directory entries |
| selected. |
| On error, \-1 is returned, with |
| .I errno |
| set to indicate the cause of the error. |
| .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 ENOENT |
| The path in \fIdirp\fR does not exist. |
| .TP |
| .B ENOMEM |
| Insufficient memory to complete the operation. |
| .TP |
| .B ENOTDIR |
| The path in \fIdirp\fR is not a directory. |
| .PP |
| The following additional errors can occur for |
| .BR scandirat (): |
| .TP |
| .B EBADF |
| .I dirfd |
| is not a valid file descriptor. |
| .TP |
| .B ENOTDIR |
| .I dirp |
| is a relative path and |
| .I dirfd |
| is a file descriptor referring to a file other than a directory. |
| .SH VERSIONS |
| .BR versionsort () |
| was added to glibc in version 2.1. |
| .PP |
| .BR scandirat () |
| was added to glibc in version 2.15. |
| .SH ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .TS |
| allbox; |
| lbw26 lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR scandir (), |
| .BR scandirat () |
| T} Thread safety MT-Safe |
| T{ |
| .BR alphasort (), |
| .BR versionsort () |
| T} Thread safety MT-Safe locale |
| .TE |
| .sp 1 |
| .SH CONFORMING TO |
| .BR alphasort (), |
| .BR scandir (): |
| 4.3BSD, POSIX.1-2008. |
| .PP |
| .BR versionsort () |
| and |
| .BR scandirat () |
| are GNU extensions. |
| .\" .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. |
| .SH NOTES |
| Since glibc 2.1, |
| .BR alphasort () |
| calls |
| .BR strcoll (3); |
| earlier it used |
| .BR strcmp (3). |
| .PP |
| Before glibc 2.10, the two arguments of |
| .BR alphasort () |
| and |
| .BR versionsort () |
| were typed as |
| .IR "const void\ *" . |
| When |
| .BR alphasort () |
| was standardized in POSIX.1-2008, |
| the argument type was specified as the type-safe |
| .IR "const struct dirent\ **", |
| and glibc 2.10 changed the definition of |
| .BR alphasort () |
| (and the nonstandard |
| .BR versionsort ()) |
| to match the standard. |
| .SH EXAMPLES |
| The program below prints a list of the files in the current directory |
| in reverse order. |
| .\" |
| .SS Program source |
| \& |
| .EX |
| #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\en", namelist[n]\->d_name); |
| free(namelist[n]); |
| } |
| free(namelist); |
| |
| exit(EXIT_SUCCESS); |
| } |
| .EE |
| .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) |