TCSBRK(2const) — Linux manual page

TCSBRK(2const)                                             TCSBRK(2const)

NAME         top

       TCSBRK, TCSBRKP, TIOCSBRK, TIOCCBRK - sending a break

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <asm/termbits.h>  /* Definition of T*BRK* constants */
       #include <sys/ioctl.h>

       int ioctl(int fd, TCSBRK, int arg);
       int ioctl(int fd, TCSBRKP, int arg);
       int ioctl(int fd, TIOCSBRK);
       int ioctl(int fd, TIOCCBRK);

DESCRIPTION         top

       TCSBRK Equivalent to tcsendbreak(fd, arg).

              If the terminal is using asynchronous serial data
              transmission, and arg is zero, then send a break (a stream
              of zero bits) for between 0.25 and 0.5 seconds.  If the
              terminal is not using asynchronous serial data
              transmission, then either a break is sent, or the function
              returns without doing anything.  When arg is nonzero,
              nobody knows what will happen.

              (SVr4, UnixWare, Solaris, and Linux treat
              tcsendbreak(fd,arg) with nonzero arg like tcdrain(fd).
              SunOS treats arg as a multiplier, and sends a stream of
              bits arg times as long as done for zero arg.  DG/UX and AIX
              treat arg (when nonzero) as a time interval measured in
              milliseconds.  HP-UX ignores arg.)

       TCSBRKP
              So-called "POSIX version" of TCSBRK.  It treats nonzero arg
              as a time interval measured in deciseconds, and does
              nothing when the driver does not support breaks.

       TIOCSBRK
              Turn break on, that is, start sending zero bits.

       TIOCCBRK
              Turn break off, that is, stop sending zero bits.

RETURN VALUE         top

       On success, 0 is returned.  On error, -1 is returned, and errno is
       set to indicate the error.

SEE ALSO         top

       ioctl(2), ioctl_tty(2)

COLOPHON         top

       This page is part of the man-pages (Linux kernel and C library
       user-space interface documentation) project.  Information about
       the project can be found at 
       ⟨https://www.kernel.org/doc/man-pages/⟩.  If you have a bug report
       for this manual page, see
       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
       This page was obtained from the tarball man-pages-6.15.tar.gz
       fetched from
       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
       2025-08-11.  If you discover any rendering problems in this HTML
       version of the page, or you believe there is a better or more up-
       to-date source for the page, or you have corrections or
       improvements to the information in this COLOPHON (which is not
       part of the original manual page), send a mail to
       man-pages@man7.org

Linux man-pages 6.15            2025-05-17                 TCSBRK(2const)

Pages that refer to this page: ioctl_tty(2)

HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.