180 lines
4.8 KiB
Groff
180 lines
4.8 KiB
Groff
.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)tcsendbreak.3 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd January 11, 2017
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.Dt TCSENDBREAK 3
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.Os
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.Sh NAME
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.Nm tcsendbreak ,
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.Nm tcdrain ,
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.Nm tcflush ,
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.Nm tcflow
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.Nd line control functions
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In termios.h
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.Ft int
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.Fn tcdrain "int fd"
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.Ft int
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.Fn tcflow "int fd" "int action"
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.Ft int
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.Fn tcflush "int fd" "int action"
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.Ft int
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.Fn tcsendbreak "int fd" "int len"
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.Sh DESCRIPTION
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The
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.Fn tcdrain
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function waits until all output written to the terminal referenced by
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.Fa fd
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has been transmitted to the terminal.
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.Pp
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The
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.Fn tcflow
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function suspends transmission of data to or the reception of data from
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the terminal referenced by
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.Fa fd
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depending on the value of
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.Fa action .
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The value of
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.Fa action
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must be one of the following:
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.Bl -tag -width "TCIOFF"
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.It Fa TCOOFF
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Suspend output.
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.It Fa TCOON
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Restart suspended output.
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.It Fa TCIOFF
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Transmit a STOP character, which is intended to cause the terminal to stop
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transmitting data to the system.
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(See the description of IXOFF in the
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.Ql Input Modes
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section of
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.Xr termios 4 ) .
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.It Fa TCION
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Transmit a START character, which is intended to cause the terminal to start
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transmitting data to the system.
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(See the description of IXOFF in the
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.Ql Input Modes
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section of
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.Xr termios 4 ) .
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.El
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.Pp
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The
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.Fn tcflush
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function discards any data written to the terminal referenced by
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.Fa fd
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which has not been transmitted to the terminal, or any data received
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from the terminal but not yet read, depending on the value of
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.Fa action .
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The value of
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.Fa action
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must be one of the following:
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.Bl -tag -width "TCIOFLUSH"
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.It Fa TCIFLUSH
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Flush data received but not read.
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.It Fa TCOFLUSH
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Flush data written but not transmitted.
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.It Fa TCIOFLUSH
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Flush both data received but not read and data written but not transmitted.
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.El
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.Pp
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The
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.Fn tcsendbreak
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function transmits a continuous stream of zero-valued bits for four-tenths
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of a second to the terminal referenced by
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.Fa fd .
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The
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.Fa len
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argument is ignored in this implementation.
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.Sh RETURN VALUES
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Upon successful completion, all of these functions return a value of zero.
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.Sh ERRORS
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If any error occurs, a value of -1 is returned and the global variable
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.Va errno
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is set to indicate the error, as follows:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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argument is not a valid file descriptor.
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.It Bq Er EINVAL
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The
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.Fa action
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argument is not a proper value.
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.It Bq Er ENOTTY
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The file associated with
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.Fa fd
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is not a terminal.
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.It Bq Er EINTR
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A signal interrupted the
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.Fn tcdrain
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function.
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.It Bq Er EWOULDBLOCK
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The configured timeout expired before the
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.Fn tcdrain
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function could write all buffered output.
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.El
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.Sh SEE ALSO
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.Xr tcsetattr 3 ,
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.Xr termios 4 ,
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.Xr tty 4 ,
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.Xr comcontrol 8
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.Sh STANDARDS
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The
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.Fn tcsendbreak ,
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.Fn tcflush
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and
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.Fn tcflow
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functions are expected to be compliant with the
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.St -p1003.1-88
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specification.
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.Pp
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The
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.Fn tcdrain
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function is expected to be compliant with
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.St -p1003.1-88
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when the drain wait value is set to zero with
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.Xr comcontrol 8 ,
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or with
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.Xr ioctl 2
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.Va TIOCSDRAINWAIT ,
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or with
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.Xr sysctl 8
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.Va kern.tty_drainwait .
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A non-zero drain wait value can result in
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.Fn tcdrain
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returning
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.Va EWOULDBLOCK
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without writing all output.
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The default value for
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.Va kern.tty_drainwait
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is 300 seconds.
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