file_desc

    The file descriptor returned by open, creat, dup, dup2, or pipe.

 a_mode

    The access mode indicator. See the fopen function for a
    description. Note that the access mode specified must agree
    with the mode used to originally open the file. This includes
    binary/text access mode ("b" mode on fdopen and the "ctx=bin"
    option on creat or open).