FIONREAD(2const) — Linux manual page

FIONREAD(2const)                                        FIONREAD(2const)

NAME

       FIONREAD, TIOCINQ, TIOCOUTQ, TCFLSH, TIOCSERGETLSR - buffer count
       and flushing

LIBRARY

       Standard C library (libc, -lc)

SYNOPSIS

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

       int ioctl(int fd, FIONREAD, int *argp);
       int ioctl(int fd, TIOCINQ, int *argp);
       int ioctl(int fd, TIOCOUTQ, int *argp);
       int ioctl(int fd, TCFLSH, int arg);
       int ioctl(int fd, FIONREAD, int *argp);

DESCRIPTION

       FIONREAD
              Get the number of bytes in the input buffer.

       TIOCINQ
              Same as FIONREAD.

       TIOCOUTQ
              Get the number of bytes in the output buffer.

       TCFLSH Equivalent to tcflush(fd, arg).

              See tcflush(3) for the argument values TCIFLUSH, TCOFLUSH,
              TCIOFLUSH.

       TIOCSERGETLSR
              Get line status register.  Status register has
              TIOCSER_TEMT bit set when output buffer is empty and also
              hardware transmitter is physically empty.

              Does not have to be supported by all serial tty drivers.

              tcdrain(3) does not wait and returns immediately when
              TIOCSER_TEMT bit is set.

RETURN VALUE

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

SEE ALSO

       ioctl(2), ioctl_tty(2), tcflush(3), termios(3)

COLOPHON

       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-6.9.1.tar.gz
       fetched from
       ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
       2024-06-26.  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 6.9.1          2024-06-13               FIONREAD(2const)

Pages that refer to this page: ioctl_tty(2)

---