ioctl(2)							   System Calls 							  ioctl(2)

NAME

       ioctl - control device

SYNOPSIS

       #include <unistd.h>
       #include <stropts.h>

       int ioctl(int fildes, int request, /* arg */ ...);

DESCRIPTION

       The ioctl() function performs a variety of control functions on devices and STREAMS. For non-STREAMS files, the functions performed by this
       call are  device-specific control functions.  The request argument and an optional third argument with varying type are passed to the  file
       designated by fildes and are interpreted by the device driver.

       For STREAMS files, specific functions are performed by the ioctl() function as described in streamio(7I).

       The  fildes argument is an open file descriptor that refers to a device.  The request argument selects the control function to be performed
       and depends on the device being addressed.  The arg argument represents a third argument that has additional information that is needed	by
       this  specific device to perform the requested function. The data type of arg depends upon the particular control request, but it is either
       an int or a pointer to a device-specific data structure.

       In addition to device-specific and STREAMS functions, generic functions are provided by more than one device driver (for example, the  gen-
       eral terminal interface.)  See termio(7I)).

RETURN VALUES

       Upon successful completion, the value returned depends upon the device control function, but must be a non-negative integer.  Otherwise, -1
       is returned and errno is set to indicate the error.

ERRORS

       The ioctl() function will fail for any type of file if:

       EBADF	       The fildes argument is not a valid open file descriptor.

       EINTR	       A signal was caught during the execution of the ioctl() function.

       EINVAL	       The STREAM or multiplexer referenced by fildes is linked (directly or indirectly) downstream from a multiplexer.

       The ioctl() function will also fail if the device driver detects an error.  In this case, the  error  is  passed  through  ioctl()  without
       change  to  the	caller.  A  particular driver might not have all of the following error cases. Under the following conditions, requests to
       device drivers may fail and set errno to indicate the error

       EFAULT	       The request argument requires a data transfer to or from a buffer pointed to by arg, but arg points to an illegal address.

       EINVAL	       The request or arg argument is not valid for this device.

       EIO	       Some physical I/O error has occurred.

       ENOLINK	       The fildes argument is on a remote machine and the link to that machine is no longer active.

       ENOTTY	       The fildes argument is not associated with a STREAMS device that accepts control functions.

       ENXIO	       The request and arg arguments are valid for this device driver, but the service requested can not be performed on this par-
		       ticular subdevice.

       ENODEV	       The  fildes  argument  refers  to  a valid STREAMS device, but the corresponding device driver does not support the ioctl()
		       function.

       STREAMS errors are described in streamio(7I).

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Standard			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       attributes(5), standards(5), streamio(7I), termio(7I)

SunOS 5.10							    15 Feb 1996 							  ioctl(2)