#### posix::basic_descriptor::bytes_readable

Inherited from posix::descriptor_base.

IO control command to get the amount of data that can be read without blocking.

    typedef implementation_defined bytes_readable;

Implements the FIONREAD IO control command.

###### Example

    asio::posix::stream_descriptor descriptor(my_context);
    ...
    asio::descriptor_base::bytes_readable command(true);
    descriptor.io_control(command);
    std::size_t bytes_readable = command.get();

###### Requirements

Header: `asio/posix/basic_descriptor.hpp`

Convenience header: `asio.hpp`