media ioctl()
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## Name

media-ioctl — Control a media device

## Synopsis

    #include <sys/ioctl.h>

`int ioctl(` | int fd,
| int request,
| void *argp`)`;

## Arguments

`fd`

  File descriptor returned by `open()`.

`request`

  Media ioctl request code as defined in the media.h header file, for example MEDIA_IOC_SETUP_LINK.

`argp`

  Pointer to a request-specific structure.

## Description

The `ioctl()` function manipulates media device parameters. The argument `fd` must be an open file descriptor.

The ioctl `request` code specifies the media function to be called. It has encoded in it whether the argument is an input, output or read/write parameter, and the size of the argument `argp` in bytes.

Macros and structures definitions specifying media ioctl requests and their parameters are located in the media.h header file. All media ioctl requests, their respective function and parameters are specified in Appendix L, Function Reference.

## Return Value

On success 0 is returned, on error -1 and the `errno` variable is set appropriately. The generic error codes are described at the Generic Error Codes chapter.

Request-specific error codes are listed in the individual requests descriptions.

When an ioctl that takes an output or read/write parameter fails, the parameter remains unmodified.

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