CONCURRENT_DOWNLOADS: Set the maximum number of parallel downloads for every queue item. See also the --split option. Default: 4
SPLIT: Download a file using N connections. If more than N URIs are given, first N URIs are used and remaining URIs are used for backup. If less than N URIs are given, those URIs are used more than once so that N connections total are made simultaneously. Default: 4
CONNECTIONS_PER_SERVER: The maximum number of connections to one server for each download. Default: 4
USER_AGENT: Set user agent for HTTP(S) downloads.