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Alphabetical listing for Special Characters

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_IO(9r)
NAME
  _IO - General: Defines ioctl types for device control operations

SYNOPSIS
  #include <sys/ioctl.h>


  _IO(
	  g,
	  n );

ARGUMENTS
  g   Specifies the group that this ioctl type belongs to. This argument must
      be a nonnegative 8-bit number (that is, in the range 0-255 inclusive).
      You can pass the value zero (0) to this argument if a new ioctl group
      is not being defined.

  n   Specifies the specific ioctl type within the group. These types should
      be sequentially assigned numbers for each different ioctl operation the
      driver supports. This argument must be a nonnegative 8-bit number (that
      is, in the range 0-255 inclusive).

DESCRIPTION
  The _IO macro defines ioctl types for situations where no data is actually
  transferred between the application program and the kernel. For example,
  this could occur in a device control operation.

EXAMPLE
  The following example uses the _IO macro to construct an ioctl called
  DN_OPERATION1. Note that DN_OPERATION1 passes the value zero (0) for the
  group that this ioctl belongs to and the value 1 to identify the specific
  ioctl type within the group.

       #define DN_OPERATION1	_IO(0,1)

SEE ALSO
  ioctl Commands: _IOR(9r), _IOW(9r), _IOWR(9r)

Index for Section 9

Alphabetical listing for Special Characters

Top of page