tcsendbreak(3)             Library Functions Manual             tcsendbreak(3)

NAME
       tcsendbreak - send a continuous stream of zero-valued bits

LIBRARY
       Standard C library (libc, -lc)

SYNOPSIS
       #include <termios.h>

       int tcsendbreak(int fd, int duration);

DESCRIPTION
       tcsendbreak() transmits a continuous stream of zero-valued bits for a
       specific duration, if the terminal is using asynchronous serial data
       transmission.

       If duration is zero, it transmits zero-valued bits for at least 0.25
       seconds, and not more than 0.5 seconds.

       If duration is not zero, it sends zero-valued bits for some
       implementation-defined length of time.

       If the terminal is not using asynchronous serial data transmission,
       tcsendbreak() returns without taking any action.

RETURN VALUE
       0      on success.

       -1     on failure and set errno to indicate the error.

ATTRIBUTES
       For an explanation of the terms used in this section, see
       attributes(7).

       +--------------------------------------------+---------------+---------+
       |Interface                                   | Attribute     | Value   |
       +--------------------------------------------+---------------+---------+
       |tcsendbreak ()                              | Thread safety | MT-Safe |
       +--------------------------------------------+---------------+---------+
VERSIONS
       The effect of a nonzero duration with tcsendbreak() varies.  SunOS
       specifies a break of duration * N seconds, where N is at least 0.25,
       and not more than 0.5.  Linux, AIX, DU, Tru64 send a break of duration
       milliseconds.  FreeBSD and NetBSD and HP-UX and MacOS ignore the value
       of duration.  Under Solaris and UnixWare, tcsendbreak() with nonzero
       duration behaves like tcdrain(3).

STANDARDS
       POSIX.1-2008.

HISTORY
       POSIX.1-2001.

SEE ALSO
       tcdrain(3), tcflush(3), tcflow(3), termios(7)

Linux man-pages 6.19              2026-07-02                    tcsendbreak(3)