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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 general
       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  descrip-
                       tor.



       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 mul-
                       tiplexer.



       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 particular 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:


       tab()     allbox;     cw(2.750000i)|    cw(2.750000i)    lw(2.750000i)|
       lw(2.750000i).  ATTRIBUTE TYPEATTRIBUTE VALUE Interface  StabilityStan-
       dard


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



SunOS 5.10                        15 Feb 1996                         ioctl(2)