FIONREAD(2const) — Linux manual page

FIONREAD(2const)                                        FIONREAD(2const)

NAME         top

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

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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         top

       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         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), tcflush(3), termios(3)

COLOPHON         top

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Linux man-pages 6.9.1          2024-06-13               FIONREAD(2const)

Pages that refer to this page: ioctl_tty(2)

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