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.
#include <termios.h> 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 action.
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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