1.\" Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org> 2.\" All rights reserved. 3.\" 4.\" Portions of this software were developed under sponsorship from Snow 5.\" B.V., the Netherlands. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" $FreeBSD$ 29.\" 30.Dd October 28, 2019 31.Dt PTY 4 32.Os 33.Sh NAME 34.Nm pty 35.Nd old-style compatibility pseudo-terminal driver 36.Sh SYNOPSIS 37.Cd "device pty" 38.Sh DESCRIPTION 39The 40.Nm 41driver provides support for the traditional BSD naming scheme that was 42used for accessing pseudo-terminals before it was replaced by 43.Xr pts 4 . 44This traditional naming is still used in Linux. 45When the device 46.Pa /dev/ptyXX 47is being opened, a new terminal shall be created with the 48.Xr pts 4 49driver. 50A device node for this terminal shall be created, which has the name 51.Pa /dev/ttyXX . 52.Pp 53The 54.Nm 55driver also provides a cloning System V 56.Pa /dev/ptmx 57device. 58.Pp 59New code should not try to allocate pseudo-terminals using this 60interface. 61It is only provided for compatibility with older C libraries 62that tried to open such devices when 63.Xr posix_openpt 2 64was being called, 65and for running Linux binaries. 66.Sh FILES 67The BSD-style compatibility pseudo-terminal driver uses the following 68device names: 69.Bl -tag -width ".Pa /dev/pty[l-sL-S][0-9a-v]" 70.It Pa /dev/pty[l-sL-S][0-9a-v] 71Pseudo-terminal master devices. 72.It Pa /dev/tty[l-sL-S][0-9a-v] 73Pseudo-terminal slave devices. 74.It Pa /dev/ptmx 75Control device, returns a file descriptor to a new master 76pseudo-terminal when opened. 77.El 78.Sh DIAGNOSTICS 79None. 80.Sh SEE ALSO 81.Xr posix_openpt 2 , 82.Xr pts 4 , 83.Xr tty 4 84.Sh HISTORY 85A 86pseudo-terminal driver appeared in 87.Bx 4.2 . 88.Sh BUGS 89Unlike previous implementations, the master and slave device nodes are 90destroyed when the PTY becomes unused. 91A call to 92.Xr stat 2 93on a nonexistent master device will already cause a new master device 94node to be created. 95The master device can only be destroyed by opening and closing it. 96.Pp 97The 98.Nm 99driver cannot be unloaded, because it cannot determine if it is being 100used. 101