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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)tcsendbreak.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd June 4, 1993 36.Dt TCSENDBREAK 3 37.Os 38.Sh NAME 39.Nm tcsendbreak , 40.Nm tcdrain , 41.Nm tcflush , 42.Nm tcflow 43.Nd line control functions 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In termios.h 48.Ft int 49.Fn tcdrain "int fd" 50.Ft int 51.Fn tcflow "int fd" "int action" 52.Ft int 53.Fn tcflush "int fd" "int action" 54.Ft int 55.Fn tcsendbreak "int fd" "int len" 56.Sh DESCRIPTION 57The 58.Fn tcdrain 59function waits until all output written to the terminal referenced by 60.Fa fd 61has been transmitted to the terminal. 62.Pp 63The 64.Fn tcflow 65function suspends transmission of data to or the reception of data from 66the terminal referenced by 67.Fa fd 68depending on the value of 69.Fa action . 70The value of 71.Fa action 72must be one of the following: 73.Bl -tag -width "TCIOFF" 74.It Fa TCOOFF 75Suspend output. 76.It Fa TCOON 77Restart suspended output. 78.It Fa TCIOFF 79Transmit a STOP character, which is intended to cause the terminal to stop 80transmitting data to the system. 81(See the description of IXOFF in the 82.Ql Input Modes 83section of 84.Xr termios 4 ) . 85.It Fa TCION 86Transmit a START character, which is intended to cause the terminal to start 87transmitting data to the system. 88(See the description of IXOFF in the 89.Ql Input Modes 90section of 91.Xr termios 4 ) . 92.El 93.Pp 94The 95.Fn tcflush 96function discards any data written to the terminal referenced by 97.Fa fd 98which has not been transmitted to the terminal, or any data received 99from the terminal but not yet read, depending on the value of 100.Fa action . 101The value of 102.Fa action 103must be one of the following: 104.Bl -tag -width "TCIOFLUSH" 105.It Fa TCIFLUSH 106Flush data received but not read. 107.It Fa TCOFLUSH 108Flush data written but not transmitted. 109.It Fa TCIOFLUSH 110Flush both data received but not read and data written but not transmitted. 111.El 112.Pp 113The 114.Fn tcsendbreak 115function transmits a continuous stream of zero-valued bits for four-tenths 116of a second to the terminal referenced by 117.Fa fd . 118The 119.Fa len 120argument is ignored in this implementation. 121.Sh RETURN VALUES 122Upon successful completion, all of these functions return a value of zero. 123.Sh ERRORS 124If any error occurs, a value of -1 is returned and the global variable 125.Va errno 126is set to indicate the error, as follows: 127.Bl -tag -width Er 128.It Bq Er EBADF 129The 130.Fa fd 131argument is not a valid file descriptor. 132.It Bq Er EINVAL 133The 134.Fa action 135argument is not a proper value. 136.It Bq Er ENOTTY 137The file associated with 138.Fa fd 139is not a terminal. 140.It Bq Er EINTR 141A signal interrupted the 142.Fn tcdrain 143function. 144.El 145.Sh SEE ALSO 146.Xr tcsetattr 3 , 147.Xr termios 4 148.Sh STANDARDS 149The 150.Fn tcsendbreak , 151.Fn tcdrain , 152.Fn tcflush 153and 154.Fn tcflow 155functions are expected to be compliant with the 156.St -p1003.1-88 157specification. 158