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.Dd October 28, 2019 29.Dt PTY 4 30.Os 31.Sh NAME 32.Nm pty 33.Nd old-style compatibility pseudo-terminal driver 34.Sh SYNOPSIS 35.Cd "device pty" 36.Sh DESCRIPTION 37The 38.Nm 39driver provides support for the traditional BSD naming scheme that was 40used for accessing pseudo-terminals before it was replaced by 41.Xr pts 4 . 42This traditional naming is still used in Linux. 43When the device 44.Pa /dev/ptyXX 45is being opened, a new terminal shall be created with the 46.Xr pts 4 47driver. 48A device node for this terminal shall be created, which has the name 49.Pa /dev/ttyXX . 50.Pp 51The 52.Nm 53driver also provides a cloning System V 54.Pa /dev/ptmx 55device. 56.Pp 57New code should not try to allocate pseudo-terminals using this 58interface. 59It is only provided for compatibility with older C libraries 60that tried to open such devices when 61.Xr posix_openpt 2 62was being called, 63and for running Linux binaries. 64.Sh FILES 65The BSD-style compatibility pseudo-terminal driver uses the following 66device names: 67.Bl -tag -width ".Pa /dev/pty[l-sL-S][0-9a-v]" 68.It Pa /dev/pty[l-sL-S][0-9a-v] 69Pseudo-terminal master devices. 70.It Pa /dev/tty[l-sL-S][0-9a-v] 71Pseudo-terminal slave devices. 72.It Pa /dev/ptmx 73Control device, returns a file descriptor to a new master 74pseudo-terminal when opened. 75.El 76.Sh DIAGNOSTICS 77None. 78.Sh SEE ALSO 79.Xr posix_openpt 2 , 80.Xr pts 4 , 81.Xr tty 4 82.Sh HISTORY 83A 84pseudo-terminal driver appeared in 85.Bx 4.2 . 86.Sh BUGS 87Unlike previous implementations, the master and slave device nodes are 88destroyed when the PTY becomes unused. 89A call to 90.Xr stat 2 91on a nonexistent master device will already cause a new master device 92node to be created. 93The master device can only be destroyed by opening and closing it. 94.Pp 95The 96.Nm 97driver cannot be unloaded, because it cannot determine if it is being 98used. 99