.\" Copyright (c) 1983, 1991, 1993
.\"	The Regents of the University of California.  All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)getdtablesize.2	8.1 (Berkeley) 6/4/93
.\"
.TH GETDTABLESIZE 2 "22 February 1996" GNO "System Calls"
.SH NAME
.BR getdtablesize
\- get descriptor table size
.SH SYNOPSIS
#include <unistd.h>
.sp 1
int
.BR getdtablesize (void);
.SH DESCRIPTION
Each process has a fixed size descriptor table,
which is guaranteed to have at least 20 slots.  The entries in
the descriptor table are numbered with small integers starting at 0.
The call
.BR getdtablesize 
returns the size of this table.
.LP
This call is mainly intended for use on systems which have configurable
kernels.  Since the GNO kernel is not yet configurable, this function
always returns
.BR OPEN_MAX .
.SH BUGS
The concept of the maximum number of concurrently open files is not 
yet consistent between GS/OS, the GNO kernel, and the C library.  For
example, the kernel uses
.BR OPEN_MAX
as the largest number of open files, yet GS/OS does not have a hard upper
limit.  It is recommended for now that the return value of
.BR getdtablesize
be assumed in applications to be the largest number of open files, as
it is the smallest value.
.SH SEE ALSO
.BR close (2),
.BR dup (2),
.BR open (2),
.BR select (2)
.SH HISTORY
The
.BR getdtablesize
function call appeared in 4.2BSD.