NetBSD/share/man/man3/unistd.3

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.\" $NetBSD: unistd.3,v 1.4 2011/08/09 18:11:38 jruoho Exp $
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.\" Copyright (c) 2011 Jukka Ruohonen <jruohonen@iki.fi>
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.Dd August 9, 2011
.Dt UNISTD 3
.Os
.Sh NAME
.Nm unistd
.Nd standard symbolic constants and types
.Sh SYNOPSIS
.In unistd.h
.Sh DESCRIPTION
The
.In unistd.h
header forms the basis of the Portable Operating System Interface for Unix
.Pq Tn POSIX
.Tn API .
It includes definitions for numerous functions, symbolic constants, and types.
Among these are:
.Bl -bullet -offset indent
.It
The implementation-defined
.Dv NULL
pointer constant.
.It
Types such as
.Vt size_t ,
.Vt ssize_t ,
.Vt pid_t ,
and
.Vt intptr_t .
.It
Various limits and other symbolic constants described in
.Xr pathconf 2
and
.Xr sysconf 3 .
.It
Prototypes for several important system calls and library routines such as
.Xr chown 2 ,
.Xr dup 2 ,
.Xr execl 3 ,
.Xr fork 2 ,
.Xr pipe 2 ,
.Xr rmdir 2 ,
.Xr setuid 2 ,
and
.Xr write 2 .
.It
The symbolic constant
.Dv _POSIX_VERSION
that defines the version of the
.Tn POSIX
standard to which the implementation conforms.
.It
Various other
.Dv _POSIX
-prefixed symbolic constants that indicate whether
the system implements some optional part of the standard.
Examples include such constants as
.Dv _POSIX_IPV6
for
.Xr inet6 4
functionality and
.Dv _POSIX_ASYNCHRONOUS_IO
for
.Xr aio 3 .
.El
.Sh SEE ALSO
.Xr limits 3 ,
.Xr stddef 3 ,
.Xr stdint 3 ,
.Xr stdlib 3 ,
.Xr types 3
.Sh STANDARDS
The
.In unistd.h
header conforms to
.St -p1003.1-2001 .
.\"
.\" XXX: fill this.
.\"
.\".Sh HISTORY
.\" A
.\" .In unistd.h
.\" header first appeared in
.\" ???