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NAME
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NAME
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ioctl - control device
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ioctl - control device
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SYNOPSIS
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SYNOPSIS
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#include <sys/ioctl.h>
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#include <sys/ioctl.h>
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int ioctl(int d, int request, ...)
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int ioctl(int d, int request, ...)
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[The "third" argument is traditionally char *argp, and
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[The "third" argument is traditionally char *argp, and
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will be so named for this discussion.]
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will be so named for this discussion.]
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DESCRIPTION
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DESCRIPTION
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The ioctl function manipulates the underlying device
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The ioctl function manipulates the underlying device
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parameters of special files. In particular, many operat-
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parameters of special files. In particular, many operat-
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ing characteristics of sockets and network devices
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ing characteristics of sockets and network devices
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may be controlled with ioctl requests. The argu-
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may be controlled with ioctl requests. The argu-
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ment d must be an open file descriptor.
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ment d must be an open file descriptor.
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An ioctl request has encoded in it whether the argument is
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An ioctl request has encoded in it whether the argument is
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an in parameter or out parameter, and the size of the
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an in parameter or out parameter, and the size of the
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argument argp in bytes. Macros and defines used in speci-
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argument argp in bytes. Macros and defines used in speci-
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fying an ioctl request are located in the file
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fying an ioctl request are located in the file
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<sys/ioctl.h>.
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<sys/ioctl.h>.
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RETURN VALUE
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RETURN VALUE
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On success, zero is returned. On error, -1 is returned,
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On success, zero is returned. On error, -1 is returned,
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and errno is set appropriately.
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and errno is set appropriately.
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ERRORS
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ERRORS
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EBADF d is not a valid descriptor.
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EBADF d is not a valid descriptor.
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EFAULT argp references an inaccessible memory area.
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EFAULT argp references an inaccessible memory area.
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ENOTTY d is not associated with a character special
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ENOTTY d is not associated with a character special
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device.
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device.
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ENOTTY The specified request does not apply to the kind of
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ENOTTY The specified request does not apply to the kind of
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object that the descriptor d references.
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object that the descriptor d references.
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EINVAL Request or argp is not valid.
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EINVAL Request or argp is not valid.
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