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.
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
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.
The tcsendbreak() function shall fail if:
EBADF The fildes argument is not a valid file descriptor.
EIO The process group of the writing process is orphaned, the
calling thread is not blocking SIGTTOU, and the process is not
ENOTTY The file associated with fildes is not a terminal.
The following sections are informative.
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2013 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 7, Copyright (C) 2013 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1
applied.) 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.unix.org/online.html .
Any typographical or formatting errors that appear in this page are
most likely to have been introduced during the conversion of the
source files to man page format. To report such errors, see
IEEE/The Open Group 2013 TCSENDBREAK(3P)