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NAME    [Toc]    [Back]

       ioctl - Control devices

SYNOPSIS    [Toc]    [Back]

       #include <stropts.h>

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

STANDARDS    [Toc]    [Back]

       Interfaces  documented  on  this reference page conform to
       industry standards as follows:

       ioctl(): XSH4.2, XSH5.0

       Refer to the standards(5) reference page for more information
 about industry standards and associated tags.

PARAMETERS    [Toc]    [Back]

       Specifies  the  file  descriptor  of the requested device.
       Specifies the ioctl()  request  to  be  performed  on  the
       device.  Specifies the parameters for request. The type of
       arg is dependent on the specific  request  and  device  to
       which  the  request is targeted.  See the appropriate Section
 7 reference page or  the  documentation  accompanying
       the device for more information.

DESCRIPTION    [Toc]    [Back]

       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 and arg parameters are  passed
       to  the  file  designated by fildes and are interpreted by
       the device driver. This control is  occasionally  used  on
       non-STREAMS devices, with the basic input/output functions
       performed through the read() and write() system calls.

       An ioctl() request has encoded in it whether the parameter
       is  an  "in" parameter or "out" parameter, and the size of
       the arg parameter in bytes. Macros  and  defines  used  to
       specify  an ioctl() request are located in the <stropts.h>
       header file.

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

       STREAMS errors are described in streamio(7).

RETURN VALUES    [Toc]    [Back]

       Upon successful completion, the ioctl() function returns a
       value other than -1 that depends upon the  STREAMS  device
       control function.

       If an error occurs, a value of -1 is returned and errno is
       set to indicate the error.

ERRORS    [Toc]    [Back]

       The ioctl() function sets errno to  the  specified  values
       for the following general conditions: The fildes parameter
       is not a valid open file descriptor.  A signal was  caught
       during  the  ioctl() operation.  The STREAM or multiplexer
       referenced by fildes is linked  (directly  or  indirectly)
       downstream from a multiplexer.

       If an underlying device driver detects an error, errno may
       be set to one of the following values: Either the  request
       or  arg  parameter  is not valid.  Some physical I/O error
       has occurred.  The fildes parameter is not associated with
       a  STREAMS device that accepts control functions. (Defined
       for Issue 4 Version 2 and higher issues of the XSH  specification.)
   [Tru64  UNIX]  The  fildes  parameter  is not
       associated with a character special device, or the  specified
 request does not apply to the kind of object that the
       fildes parameter references.  The request and arg  parameters
  are  valid  for  this device driver, but the service
       requested cannot be performed on the particular subdevice.
       The fildes parameter refers to a valid STREAMS device, but
       the corresponding  device  driver  does  not  support  the
       ioctl() function.

SEE ALSO    [Toc]    [Back]

       Functions: exec(2), fcntl(2)

       Files: proc(4) tty(7), nifftmt(7), streamio(7)

       Standards: standards(5)

[ Back ]
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