This manual page is part of the POSIX Programmer's Manual. The Linux
implementation of this interface may differ (consult the corresponding Linux
manual page for details of Linux behavior), or the interface may not be
implemented on Linux.
tcsendbreak — send a break for a specific duration
int tcsendbreak(int fildes, int duration);
If the terminal is using asynchronous serial data transmission,
tcsendbreak() shall cause transmission of a continuous stream of
zero-valued bits for a specific duration. If duration is 0, it shall
cause transmission of zero-valued bits for at least 0.25 seconds, and not more
than 0.5 seconds. If duration is not 0, it shall send zero-valued bits
for an implementation-defined period of time.
The fildes argument is an open file descriptor associated
with a terminal.
If the terminal is not using asynchronous serial data
transmission, it is implementation-defined whether tcsendbreak()
sends data to generate a break condition or returns without taking any
Attempts to use tcsendbreak() from a process which is a
member of a background process group on a fildes associated with its
controlling terminal shall cause the process group to be sent a SIGTTOU
signal. If the calling thread is blocking SIGTTOU signals or the process is
ignoring SIGTTOU signals, the process shall be allowed to perform the
operation, and no signal is sent.
Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned
and errno set to indicate the error.
The tcsendbreak() function shall fail if:
- The fildes argument is not a valid file descriptor.
- The process group of the writing process is orphaned, the calling thread
is not blocking SIGTTOU, and the process is not ignoring SIGTTOU.
- The file associated with fildes is not a terminal.
The following sections are informative.
The Base Definitions volume of POSIX.1‐2017, Chapter 11,
General Terminal Interface, <termios.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1-2017, Standard for Information Technology -- Portable Operating
System Interface (POSIX), The Open Group Base Specifications Issue 7, 2018
Edition, Copyright (C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html .
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