1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.\" @(#)tcsendbreak.3 8.1 (Berkeley) 6/4/93 29.\" $FreeBSD$ 30.\" 31.Dd January 11, 2017 32.Dt TCSENDBREAK 3 33.Os 34.Sh NAME 35.Nm tcsendbreak , 36.Nm tcdrain , 37.Nm tcflush , 38.Nm tcflow 39.Nd line control functions 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In termios.h 44.Ft int 45.Fn tcdrain "int fd" 46.Ft int 47.Fn tcflow "int fd" "int action" 48.Ft int 49.Fn tcflush "int fd" "int action" 50.Ft int 51.Fn tcsendbreak "int fd" "int len" 52.Sh DESCRIPTION 53The 54.Fn tcdrain 55function waits until all output written to the terminal referenced by 56.Fa fd 57has been transmitted to the terminal. 58.Pp 59The 60.Fn tcflow 61function suspends transmission of data to or the reception of data from 62the terminal referenced by 63.Fa fd 64depending on the value of 65.Fa action . 66The value of 67.Fa action 68must be one of the following: 69.Bl -tag -width "TCIOFF" 70.It Fa TCOOFF 71Suspend output. 72.It Fa TCOON 73Restart suspended output. 74.It Fa TCIOFF 75Transmit a STOP character, which is intended to cause the terminal to stop 76transmitting data to the system. 77(See the description of IXOFF in the 78.Ql Input Modes 79section of 80.Xr termios 4 ) . 81.It Fa TCION 82Transmit a START character, which is intended to cause the terminal to start 83transmitting data to the system. 84(See the description of IXOFF in the 85.Ql Input Modes 86section of 87.Xr termios 4 ) . 88.El 89.Pp 90The 91.Fn tcflush 92function discards any data written to the terminal referenced by 93.Fa fd 94which has not been transmitted to the terminal, or any data received 95from the terminal but not yet read, depending on the value of 96.Fa action . 97The value of 98.Fa action 99must be one of the following: 100.Bl -tag -width "TCIOFLUSH" 101.It Fa TCIFLUSH 102Flush data received but not read. 103.It Fa TCOFLUSH 104Flush data written but not transmitted. 105.It Fa TCIOFLUSH 106Flush both data received but not read and data written but not transmitted. 107.El 108.Pp 109The 110.Fn tcsendbreak 111function transmits a continuous stream of zero-valued bits for four-tenths 112of a second to the terminal referenced by 113.Fa fd . 114The 115.Fa len 116argument is ignored in this implementation. 117.Sh RETURN VALUES 118Upon successful completion, all of these functions return a value of zero. 119.Sh ERRORS 120If any error occurs, a value of -1 is returned and the global variable 121.Va errno 122is set to indicate the error, as follows: 123.Bl -tag -width Er 124.It Bq Er EBADF 125The 126.Fa fd 127argument is not a valid file descriptor. 128.It Bq Er EINVAL 129The 130.Fa action 131argument is not a proper value. 132.It Bq Er ENOTTY 133The file associated with 134.Fa fd 135is not a terminal. 136.It Bq Er EINTR 137A signal interrupted the 138.Fn tcdrain 139function. 140.It Bq Er EWOULDBLOCK 141The configured timeout expired before the 142.Fn tcdrain 143function could write all buffered output. 144.El 145.Sh SEE ALSO 146.Xr tcsetattr 3 , 147.Xr termios 4 , 148.Xr tty 4 , 149.Xr comcontrol 8 150.Sh STANDARDS 151The 152.Fn tcsendbreak , 153.Fn tcflush 154and 155.Fn tcflow 156functions are expected to be compliant with the 157.St -p1003.1-88 158specification. 159.Pp 160The 161.Fn tcdrain 162function is expected to be compliant with 163.St -p1003.1-88 164when the drain wait value is set to zero with 165.Xr comcontrol 8 , 166or with 167.Xr ioctl 2 168.Va TIOCSDRAINWAIT , 169or with 170.Xr sysctl 8 171.Va kern.tty_drainwait . 172A non-zero drain wait value can result in 173.Fn tcdrain 174returning 175.Va EWOULDBLOCK 176without writing all output. 177The default value for 178.Va kern.tty_drainwait 179is 300 seconds. 180