Aria2是一个命令行下运行、多协议、多来源">下载工具（HTTP/HTTPS、FTP、BitTorrent、Metalink），内建 XML-RPC 用户界面。
Aria2是Linux 下一个不错的高速下载工具。由于它具有分段下载引擎，所以支持从多个地址或者从一个地址的多个连接来下载同一个文件。这样自然就大大加快了文件的下载速度。aria2 也具有断点续传功能，这使你随时能够恢复已经中断的文件下载。除了支持一般的 http(s) 和 ftp 协议外，aria2 还支持 BitTorrent 协议。这意味着，你也可以使用 aria2 来下载 torrent 文件。
Aria2详解的安装及使用说明，请参阅风信网《Aria2一个命令行下运行、多协议、多来源下载工具》的介绍：http://www.ithov.com/linux/ubuntu/software/100769.shtml
aria2 1.12.0更新日志：
* Use ServerStat to find faster server. This is useful when several downloads were started in parallel, but one download is slow and the other downloads have completed. Then aria2 knows which servers are fast by the results of completed downloads, and check the available URIs of slow downloads to see faster server is available there. If so, use it instead of current slow one to make download faster.
* Added Russian translation of man page and HTML manual contributed by ITriskTI.
* Added aria2.getGlobalStat RPC method. It returns overall download/upload speed and the number of active/stopped/waiting downloads.
* Added --pause option. This option pauses download after added. This option is effective only when --enable-rpc=true is given. When --save-session option is used and there are paused downloads, they are saved with --pause=true so that it will become paused state when the session is recovered.
* Abort aria2 if it could not setup any RPC server.
* Added --truncate-console-readout option. This option truncates console readout to fit in a single line. This is default. Give false value to this option to tell aria2 not to truncate console readout.
* Cache and reuse RpcMethod objects.
* Allowed missing params in system.multicall RPC method.
* Added --stream-piece-selector option. This option specifies piece selection algorithm used in HTTP/FTP download. Piece means fixed length segment which is downloaded in parallel in segmented download. If 'default' is given, aria2 selects piece so that it reduces the number of establishing connection. This is reasonable default behaviour because establishing connection is an expensive operation. If 'inorder' is given, aria2 selects piece which has minimum index. Index=0 means first of the file. This will be useful to view movie while downloading it. --enable-http-pipelining option
may be useful to reduce reconnection overhead. Please note that aria2 honors --min-split-size option, so it will be necessary to specify a reasonable value to --min-split-size option.
* Removed unnecessary template parameter from std::make_pair call. The patch was contributed from Dan Fandrich.
* Implemented fast file allocation in MinGW32 build. We use SetFilePointerEx and SetEndOfFile to allocate extents.This only works with NTFS. To enable this feature, --file-allocation=falloc must be given.
* Only percent-encode non-printable ASCII chars(0x00-0x1f), non-ASCII chars(>0x7f), ' ', '"', '<' and '>' for URIs supplied by user and remote server(usually Location header field).
* Don't throw exception if Z_BUF_ERROR is encountered in GZipEncoder. This fixed the bug that compressed RPC request failed.
* Don't save removed download in --save-session text file. Now stat column of removed downloads in Download Results is 'RM' instead of INPR.
下载地址：
http://sourceforge.net/projects/aria2/files/stable/aria2-1.12.0/aria2-1.12.0.tar.gz/download
http://sourceforge.net/projects/aria2/files/stable/aria2-1.12.0/aria2-1.12.0.tar.xz/download
http://sourceforge.net/projects/aria2/files/stable/aria2-1.12.0/aria2-1.12.0.tar.bz2/download