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)

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