aria2 is a lightweight multi-protocol & multi-source, cross platform download utility operated in command-line. It supports HTTP/HTTPS, FTP, SFTP, BitTorrent and Metalink.https://aria2.github.io/
If true is given, which is default, save the uploaded torrent or
metalink metadata in the directory specified by --dir option. The
filename consists of SHA1-hash hex string of metadata plus
extension. For torrent, the extension is '.torrent'. For metalink, it
is '.meta4'. If false is given to this option, the downloads added by
aria2.addTorrent or aria2.addMetalink will not be saved by
--save-session option.