'\" te
.\" Copyright (c) 2001, the Institute of Electrical and Electronics Engineers, Inc. and The Open Group. All Rights Reserved.
.\" Portions Copyright (c) 2003, Sun Microsystems, Inc. All Rights Reserved.
.\"  Sun Microsystems, Inc. gratefully acknowledges The Open Group for permission to reproduce portions of its copyrighted documentation. Original documentation from The Open Group can be obtained online at  http://www.opengroup.org/bookstore/.
.\" The Institute of Electrical and Electronics Engineers and The Open Group, have given us permission to reprint portions of their documentation. In the following statement, the phrase "this text" refers to portions of the system documentation. Portions of this text are reprinted and reproduced in electronic form in the Sun OS Reference Manual, from IEEE Std 1003.1, 2004 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2004 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between these versions and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html.  This notice shall appear on any product containing this material. 
.TH posix_openpt 3C "1 Dec 2003" "SunOS 5.11" "Standard C Library Functions"
.SH NAME
posix_openpt \- open a pseudo terminal device
.SH SYNOPSIS
.LP
.nf
#include <stdlib.h>
#include <fcntl.h>

\fBint\fR \fBposix_openpt\fR(\fBint\fR \fIoflag\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBposix_openpt()\fR function establishes a connection between a master device for a pseudo-terminal and a file descriptor. The file descriptor is used by other I/O functions that refer to that pseudo-terminal.
.sp
.LP
The file status flags and file access modes of the open file description are set according to the value of \fIoflag\fR.
.sp
.LP
Values for \fIoflag\fR are constructed by a bitwise-inclusive OR of flags from the following list, defined in <\fBfcntl.h\fR>.
.sp
.ne 2
.mk
.na
\fB\fBO_RDWR\fR\fR
.ad
.RS 12n
.rt  
Open for reading and writing.
.RE

.sp
.ne 2
.mk
.na
\fB\fBO_NOCTTY\fR\fR
.ad
.RS 12n
.rt  
If set, \fBposix_openpt()\fR does not cause the terminal device to become the controlling terminal for the process.
.RE

.sp
.LP
The behavior of other values for the \fIoflag\fR argument is unspecified.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, the \fBposix_openpt()\fR function opens a master pseudo-terminal device and returns a non-negative integer representing the lowest numbered unused file descriptor. Otherwise, -1 is returned and \fBerrno\fR is set to indicate the error.
.SH ERRORS
.sp
.LP
The \fBposix_openpt()\fR function will fail if:
.sp
.ne 2
.mk
.na
\fB\fBEMFILE\fR\fR
.ad
.RS 10n
.rt  
{\fBOPEN_MAX\fR} file descriptors are currently open in the calling process.
.RE

.sp
.ne 2
.mk
.na
\fB\fBENFILE\fR\fR
.ad
.RS 10n
.rt  
The maximum allowable number of files is currently open in the system.
.RE

.sp
.LP
The \fBposix_openpt()\fR function may fail if:
.sp
.ne 2
.mk
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
.rt  
The value of \fIoflag\fR is not valid.
.RE

.sp
.ne 2
.mk
.na
\fB\fBEAGAIN\fR\fR
.ad
.RS 10n
.rt  
Out of pseudo-terminal resources.
.RE

.sp
.ne 2
.mk
.na
\fB\fBENOSR\fR\fR
.ad
.RS 10n
.rt  
Out of STREAMS resources.
.RE

.SH EXAMPLES
.LP
\fBExample 1 \fROpen a pseudo-terminal.
.sp
.LP
The following example opens a pseudo-terminal and returns the name of the slave device and a file descriptor.

.sp
.in +2
.nf
#include fcntl.h>
#include stdio.h>

int masterfd, slavefd;
char *slavedevice;

masterfd = posix_openpt(O_RDWR|O_NOCTTY);

if (masterfd == -1
      || grantpt (masterfd) == -1
      || unlockpt (masterfd) == -1
      || (slavedevice = ptsname (masterfd)) == NULL)
      return -1;

printf("slave device is: %s\en", slavedevice);

slavefd = open(slave, O_RDWR|O_NOCTTY);
if (slavefd < 0)
      return -1;
.fi
.in -2

.SH USAGE
.sp
.LP
This function provides a method for portably obtaining a file descriptor of a master terminal device for a pseudo-terminal. The \fBgrantpt\fR(3C) and \fBptsname\fR(3C) functions can be used to manipulate mode and ownership permissions and to obtain the name of the slave device, respectively.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
tab() box;
cw(2.75i) |cw(2.75i) 
lw(2.75i) |lw(2.75i) 
.
ATTRIBUTE TYPEATTRIBUTE VALUE
_
Interface StabilityCommitted
_
MT-LevelMT-Safe
_
StandardSee \fBstandards\fR(5).
.TE

.SH SEE ALSO
.sp
.LP
\fBopen\fR(2), \fBgrantpt\fR(3C), \fBptsname\fR(3C), \fBunlockpt\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)