1.\" $OpenBSD: posix_openpt.3,v 1.4 2019/01/25 00:19:25 millert Exp $ 2.\" 3.\" Copyright (c) 2012 Todd C. Miller <millert@openbsd.org> 4.\" 5.\" Permission to use, copy, modify, and distribute this software for any 6.\" purpose with or without fee is hereby granted, provided that the above 7.\" copyright notice and this permission notice appear in all copies. 8.\" 9.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16.\" 17.Dd $Mdocdate: January 25 2019 $ 18.Dt POSIX_OPENPT 3 19.Os 20.Sh NAME 21.Nm posix_openpt 22.Nd open a pseudo-terminal device 23.Sh SYNOPSIS 24.In stdlib.h 25.In fcntl.h 26.Ft int 27.Fn posix_openpt "int oflag" 28.Sh DESCRIPTION 29The 30.Fn posix_openpt 31function finds the next available pseudo-terminal and returns an open 32file descriptor for its master device. 33The path name of the slave device may be determined via the 34.Fn ptsname 35function. 36Note that the 37.Fn unlockpt 38and 39.Fn grantpt 40functions should be called before opening the slave device. 41.Pp 42The 43.Ar oflag 44argument is formed by bitwise-inclusive 45.Tn OR Ns 'ing 46the following values defined in 47.In fcntl.h : 48.Bl -tag -width O_NOCTTY -offset indent 49.It Dv O_RDWR 50Open for reading and writing. 51.It Dv O_NOCTTY 52Prevent the device from being made the controlling terminal for the session. 53This flag has no effect on 54.Ox 55and is included for compatibility with other systems. 56.El 57.Pp 58The 59.Dv O_RDWR 60flag must be specified in 61.Fa oflag . 62If 63.Fa oflag 64contains values other than those listed above, 65.Fn posix_openpt 66will return an error. 67.Sh RETURN VALUES 68If successful, 69.Fn posix_openpt 70returns a non-negative integer, the file descriptor for the 71pseudo-terminal master device. 72Otherwise, a value of \-1 is returned and 73.Va errno 74is set to indicate the error. 75.Sh ERRORS 76The 77.Fn posix_openpt 78function will fail if: 79.Bl -tag -width Er 80.It Bq Er EMFILE 81The per-process descriptor table is full. 82.It Bq Er ENFILE 83The system file table is full. 84.It Bq Er EINVAL 85The value of 86.Fa oflag 87is not valid. 88.El 89.Sh SEE ALSO 90.Xr ptsname 3 , 91.Xr pty 4 , 92.Xr tty 4 93.Sh STANDARDS 94The 95.Fn posix_openpt 96function conforms to 97.St -p1003.1-2001 . 98.Sh HISTORY 99The 100.Fn posix_openpt 101function appeared in 102.Ox 5.3 . 103