int fcntl(int fd, int cmd, size_t arg);
Issues a file descriptor command. The available commands vary by platform, but the most common commands, such as F_SETFL, are available on all platforms. Returns the result of the command, the meaning of which varies by the command sent.
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In the standard C runtime implementation of this function, the arg parameter is optional. This runtime always requires the third argument. For commands that do not need the arg parameter, it will be ignored. The __undefined intrinsic can be used for ignored parameters. |