.\" $NetBSD: unlockpt.3,v 1.4 2008/04/30 13:10:51 martin Exp $
.\"
.\" Copyright (c) 2004 The NetBSD Foundation, Inc.
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.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Christos Zoulas.
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.Dd May 25, 2004
.Dt UNLOCKPT 3
.Os
.Sh NAME
.Nm unlockpt
.Nd unlock the slave pseudo-terminal device
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In stdlib.h
.Ft int
.Fn unlockpt "int fildes"
.Sh DESCRIPTION
The
.Fn unlockpt
unlocks access to the pseudo-terminal device corresponding to the
master pseudo-terminal device associated with
.Fa fildes .
Conforming applications must call this function before opening the
slave pseudo-terminal device.
.Sh RETURN VALUES
If successful,
.Fn unlockpt
returns 0; otherwise a value of \-1 is returned and
.Va errno
is set to indicate the error.
.Sh ERRORS
The
.Fn unlockpt
function will fail if:
.Bl -tag -width Er
.It Bq Er EACCESS
the corresponding pseudo-terminal device could not be accessed.
.It Bq Er EBADF
.Fa fildes
is not a valid descriptor.
.It Bq Er EINVAL
.Fa fildes
is not associated with a master pseudo-terminal device.
.El
.Sh NOTES
In
.Nx
.Fn unlockpt
does nothing.
.Sh SEE ALSO
.Xr ioctl 2 ,
.Xr grantpt 3 ,
.Xr posix_openpt 3 ,
.Xr ptsname 3
.Sh STANDARDS
The
.Fn unlockpt
function conforms to
.St -p1003.1-2001 .
Its first release was in
.St -xpg4.2 .