1.\" $OpenBSD: openpty.3,v 1.11 2003/06/02 20:18:42 millert Exp $ 2.\" Copyright (c) 1995 3.\" The Regents of the University of California. All rights reserved. 4.\" 5.\" This code is derived from software developed by the Computer Systems 6.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract 7.\" BG 91-66 and contributed to Berkeley. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. Neither the name of the University nor the names of its contributors 18.\" may be used to endorse or promote products derived from this software 19.\" without specific prior written permission. 20.\" 21.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31.\" SUCH DAMAGE. 32.\" 33.Dd November 4, 1996 34.Dt OPENPTY 3 35.Os 36.Sh NAME 37.Nm openpty , 38.Nm login_tty , 39.Nm forkpty 40.Nd tty utility functions 41.Sh SYNOPSIS 42.Fd #include <termios.h> 43.Fd #include <util.h> 44.Ft int 45.Fn openpty "int *amaster" "int *aslave" "char *name" "struct termios *termp" "struct winsize *winp" 46.Ft int 47.Fn login_tty "int fd" 48.Ft pid_t 49.Fn forkpty "int *amaster" "char *name" "struct termios *termp" "struct winsize *winp" 50.Sh DESCRIPTION 51The 52.Fn openpty , 53.Fn login_tty , 54and 55.Fn forkpty 56functions perform manipulations on ttys and pseudo-ttys. 57.Pp 58The 59.Fn openpty 60function finds an available pseudo-tty and returns file descriptors 61for the master and slave in 62.Fa amaster 63and 64.Fa aslave . 65If 66.Fa name 67is non-null, the filename of the slave is returned in 68.Fa name 69(a string of at least 16 characters). 70If 71.Fa termp 72is non-null, the terminal parameters of the slave will be set to the 73values in 74.Fa termp . 75If 76.Fa winp 77is non-null, the window size of the slave will be set to the values in 78.Fa winp . 79.Pp 80The 81.Fn login_tty 82function prepares for a login on the tty 83.Fa fd 84(which may be a real tty device, or the slave of a pseudo-tty as 85returned by 86.Fn openpty ) 87by creating a new session, making 88.Fa fd 89the controlling terminal for the current process, setting 90.Fa fd 91to be the standard input, output, and error streams of the current 92process, and closing 93.Fa fd . 94.Pp 95The 96.Fn forkpty 97function combines 98.Fn openpty , 99.Fn fork , 100and 101.Fn login_tty 102to create a new process operating in a pseudo-tty. 103The file 104descriptor of the master side of the pseudo-tty is returned in 105.Fa amaster , 106and the filename of the slave in 107.Fa name 108if it is non-null. 109The 110.Fa termp 111and 112.Fa winp 113parameters, if non-null, will determine the terminal attributes and 114window size of the slave side of the pseudo-tty. 115.Sh RETURN VALUES 116If a call to 117.Fn openpty , 118.Fn login_tty , 119or 120.Fn forkpty 121is not successful, \-1 is returned and 122.Va errno 123is set to indicate the error. 124Otherwise, 125.Fn openpty , 126.Fn login_tty , 127and the child process of 128.Fn forkpty 129return 0, and the parent process of 130.Fn forkpty 131returns the process ID of the child process. 132.Sh FILES 133.Bl -tag -width /dev/[pt]ty[pqrstuvwxyzPQRST][0123456789abcdef] -compact 134.It Pa /dev/[pt]ty[pqrstuvwxyzPQRST][0123456789abcdef] 135.El 136.Sh ERRORS 137.Fn openpty 138will fail if: 139.Bl -tag -width Er 140.It Bq Er ENOENT 141There are no available ttys. 142.El 143.Pp 144.Fn login_tty 145will fail if 146.Fn ioctl 147fails to set 148.Fa fd 149to the controlling terminal of the current process. 150.Fn forkpty 151will fail if either 152.Fn openpty 153or 154.Fn fork 155fails. 156.Sh SEE ALSO 157.Xr fork 2 158