1.\" Copyright (c) 1995 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software developed by the Computer Systems 5.\" Engineering group at Lawrence Berkeley Laboratory under DARPA contract 6.\" BG 91-66 and contributed to Berkeley. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.Dd December 14, 1995 37.Dt OPENPTY 3 38.Os 39.Sh NAME 40.Nm openpty , 41.Nm login_tty , 42.Nm forkpty 43.Nd tty utility functions 44.Sh SYNOPSIS 45.Fd #include <util.h> 46.Ft void 47.Fn openpty "int *amaster" "int *aslave" "char *name" "struct termios *termp" "struct winsize *winp" 48.Ft int 49.Fn login_tty "int fd" 50.Ft pid_t 51.Fn forkpty "int *amaster" "char *name" "struct termios *termp" "struct winsize *winp" 52.Sh DESCRIPTION 53The 54.Fn openpty , 55.Fn login_tty , 56and 57.Fn login_tty 58functions perform manipulations on ttys and pseudo-ttys. 59.Pp 60The 61.Fn openpty 62function finds an available pseudo-tty and returns file descriptors 63for the master and slave in 64.Fa amaster 65and 66.Fa aslave . 67If 68.Fa name 69is non-null, the filename of the slave is returned in 70.Fa name . 71If 72.Fa termp 73is non-null, the terminal parameters of the slave will be set to the 74values in 75.Fa termp . 76If 77.Fa winp 78is non-null, the window size of the slave will be set to the values in 79.Fa winp . 80.Pp 81The 82.Fn login_tty 83function prepares for a login on the tty 84.Fa fd 85(which may be a real tty device, or the slave of a pseudo-tty as 86returned by 87.Fn openpty ) 88by creating a new session, making 89.Fa fd 90the controlling terminal for the current process, setting 91.Fa fd 92to be the standard input, output, and error streams of the current 93process, and closing 94.Fa fd . 95.Pp 96The 97.Fn forkpty 98function combines 99.Fn openpty , 100.Fn fork , 101and 102.Fn login_tty 103to creates a new process operating in a pseudo-tty. The 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. The 109.Fa termp 110and 111.Fa winp 112parameters, if non-null, will determine the terminal attributes and 113window size of the slave side of the pseudo-tty. 114.Sh RETURN VALUES 115If a call to 116.Fn openpty , 117.Fn login_tty , 118or 119.fn forkpty 120is not successful, -1 is returned and 121.Va errno 122is set to indicate the error. Otherwise, they return 0. 123.Sh ERRORS 124.Fn openpty 125will fail if: 126.Bl -tag -width Er 127.It Bq Er ENOENT 128There are no available ttys. 129.El 130.Pp 131.Fn login_tty 132will fail if 133.Fn ioctl 134fails to set 135.Fa fd 136to the controlling terminal of the current process. 137.Fn forkpty 138will fail if either 139.Fn openpty 140or 141.Fn fork 142fails. 143.Sh FILES 144.Bl -tag -width /dev/[pt]ty[pqrstuwxyzPQRST][0123456789abcdef] -compact 145.It Pa /dev/[pt]ty[pqrstuwxyzPQRST][0123456789abcdef] 146.El 147.Sh BUGS 148The names of the virtual consoles for the i386 PCVT console driver 149conflict with what would be the seventh group of pseudo-ttys, so 150.Fn openpty 151skips 152.Pa /dev/[pt]tyv[0123456789abcdef] 153while looking for pseudo-ttys. 154