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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.Dd January 11, 2017 29.Dt TCSENDBREAK 3 30.Os 31.Sh NAME 32.Nm tcsendbreak , 33.Nm tcdrain , 34.Nm tcflush , 35.Nm tcflow 36.Nd line control functions 37.Sh LIBRARY 38.Lb libc 39.Sh SYNOPSIS 40.In termios.h 41.Ft int 42.Fn tcdrain "int fd" 43.Ft int 44.Fn tcflow "int fd" "int action" 45.Ft int 46.Fn tcflush "int fd" "int action" 47.Ft int 48.Fn tcsendbreak "int fd" "int len" 49.Sh DESCRIPTION 50The 51.Fn tcdrain 52function waits until all output written to the terminal referenced by 53.Fa fd 54has been transmitted to the terminal. 55.Pp 56The 57.Fn tcflow 58function suspends transmission of data to or the reception of data from 59the terminal referenced by 60.Fa fd 61depending on the value of 62.Fa action . 63The value of 64.Fa action 65must be one of the following: 66.Bl -tag -width "TCIOFF" 67.It Fa TCOOFF 68Suspend output. 69.It Fa TCOON 70Restart suspended output. 71.It Fa TCIOFF 72Transmit a STOP character, which is intended to cause the terminal to stop 73transmitting data to the system. 74(See the description of IXOFF in the 75.Ql Input Modes 76section of 77.Xr termios 4 ) . 78.It Fa TCION 79Transmit a START character, which is intended to cause the terminal to start 80transmitting data to the system. 81(See the description of IXOFF in the 82.Ql Input Modes 83section of 84.Xr termios 4 ) . 85.El 86.Pp 87The 88.Fn tcflush 89function discards any data written to the terminal referenced by 90.Fa fd 91which has not been transmitted to the terminal, or any data received 92from the terminal but not yet read, depending on the value of 93.Fa action . 94The value of 95.Fa action 96must be one of the following: 97.Bl -tag -width "TCIOFLUSH" 98.It Fa TCIFLUSH 99Flush data received but not read. 100.It Fa TCOFLUSH 101Flush data written but not transmitted. 102.It Fa TCIOFLUSH 103Flush both data received but not read and data written but not transmitted. 104.El 105.Pp 106The 107.Fn tcsendbreak 108function transmits a continuous stream of zero-valued bits for four-tenths 109of a second to the terminal referenced by 110.Fa fd . 111The 112.Fa len 113argument is ignored in this implementation. 114.Sh RETURN VALUES 115Upon successful completion, all of these functions return a value of zero. 116.Sh ERRORS 117If any error occurs, a value of -1 is returned and the global variable 118.Va errno 119is set to indicate the error, as follows: 120.Bl -tag -width Er 121.It Bq Er EBADF 122The 123.Fa fd 124argument is not a valid file descriptor. 125.It Bq Er EINVAL 126The 127.Fa action 128argument is not a proper value. 129.It Bq Er ENOTTY 130The file associated with 131.Fa fd 132is not a terminal. 133.It Bq Er EINTR 134A signal interrupted the 135.Fn tcdrain 136function. 137.It Bq Er EWOULDBLOCK 138The configured timeout expired before the 139.Fn tcdrain 140function could write all buffered output. 141.El 142.Sh SEE ALSO 143.Xr tcsetattr 3 , 144.Xr termios 4 , 145.Xr tty 4 , 146.Xr comcontrol 8 147.Sh STANDARDS 148The 149.Fn tcsendbreak , 150.Fn tcflush 151and 152.Fn tcflow 153functions are expected to be compliant with the 154.St -p1003.1-88 155specification. 156.Pp 157The 158.Fn tcdrain 159function is expected to be compliant with 160.St -p1003.1-88 161when the drain wait value is set to zero with 162.Xr comcontrol 8 , 163or with 164.Xr ioctl 2 165.Va TIOCSDRAINWAIT , 166or with 167.Xr sysctl 8 168.Va kern.tty_drainwait . 169A non-zero drain wait value can result in 170.Fn tcdrain 171returning 172.Va EWOULDBLOCK 173without writing all output. 174The default value for 175.Va kern.tty_drainwait 176is 300 seconds. 177