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.\"     @(#)scandir.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD: head/lib/libc/gen/scandir.3 276006 2014-12-21 12:36:36Z brueffer $
.\"
.Dd January 3, 2010
.Dt SCANDIR 3
.Os
.Sh NAME
.Nm scandir ,
.Nm alphasort
.Nd scan a directory
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In dirent.h
.Ft int
.Fn scandir "const char *dirname" "struct dirent ***namelist" "int \*(lp*select\*(rp\*(lpconst struct dirent *\*(rp" "int \*(lp*compar\*(rp\*(lpconst struct dirent **, const struct dirent **\*(rp"
.Ft int
.Fn scandir_b "const char *dirname" "struct dirent ***namelist" "int \*(lp*select\^(rp\*(lpconst struct dirent *\*(rp" "int \*(lp^compar\*(rp\*(lpconst struct dirent **, const struct dirent **\*(rp"
.Ft int
.Fn alphasort "const struct dirent **d1" "const struct dirent **d2"
.Sh DESCRIPTION
The
.Fn scandir
function
reads the directory
.Fa dirname
and builds an array of pointers to directory
entries using
.Xr malloc 3 .
It returns the number of entries in the array.
A pointer to the array of directory entries is stored in the location
referenced by
.Fa namelist .
.Pp
The
.Fa select
argument is a pointer to a user supplied subroutine which is called by
.Fn scandir
to select which entries are to be included in the array.
The select routine is passed a
pointer to a directory entry and should return a non-zero
value if the directory entry is to be included in the array.
If
.Fa select
is null, then all the directory entries will be included.
.Pp
The
.Fa compar
argument is a pointer to a user supplied subroutine which is passed to
.Xr qsort 3
to sort the completed array.
If this pointer is null, the array is not sorted.
.Pp
The
.Fn alphasort
function
is a routine which can be used for the
.Fa compar
argument to sort the array alphabetically using
.Xr strcoll 3 .
.Pp
The memory allocated for the array can be deallocated with
.Xr free 3 ,
by freeing each pointer in the array and then the array itself.
.Pp
The
.Fn scandir_b
function behaves in the same way as
.Fn scandir ,
but takes blocks as arguments instead of function pointers and calls
.Fn qsort_b
rather than
.Fn qsort .
.Sh DIAGNOSTICS
Returns \-1 if the directory cannot be opened for reading or if
.Xr malloc 3
cannot allocate enough memory to hold all the data structures.
.Sh SEE ALSO
.Xr directory 3 ,
.Xr malloc 3 ,
.Xr qsort 3 ,
.Xr strcoll 3 ,
.Xr dir 5
.Sh HISTORY
The
.Fn scandir
and
.Fn alphasort
functions appeared in
.Bx 4.2 .