I used to download the large files with wget because I can simply
resume the download tasks with -c option. This option will check
the size of the output file, and download the rest of the file from the server.
I can even restart the download task with a different URI. This feature
is not available in many sophisticated download managers.
Recently, I came across Aria2, which is a command line download manager
which supports lots of protocols, including HTTP, FTP, BitTorrents, and etc.
Similar to wget, I can resume the download tasks without problems! And
there are several features which are not available in wget:
- Multiple tasks and scheduling
- Split the download task and download the file in parallel
- Web UI
- ... and etc
In this post, I would like to give a brief introduction to Aria2.
Installation
Before we can start our discussion, we have to install Aria2 first.
To install Aria2 on Ubuntu (or Debian), run the following command:
$ sudo apt-get install aria2
Besides, check the file permission of your .netrc file. It should be
600, i.e. only the owner can read or write the file. You can change the
file permission with following command:
$ chmod 600 ~/.netrc
Download Files with Aria2
Aria2 is similar to wget command line tool. We can simply download
the files with aria2c command:
$ aria2c [URI]
For example, to download the Debian 7.8 minimal CD image:
$ aria2c http://cdimage.debian.org/debian-cd/7.8.0/amd64/iso-cd/debian-7.8.0-amd64-netinst.iso
We can specify the output file name with -o option:
$ aria2c [URI] -o [filename]
To resume a download task, we can specify the -c option:
$ aria2c -c [URI]
$ aria2c -c [URI] -o [filename]
If we wish to download a file parallelly, we can try the -x option:
$ aria2c -x[num-parts] [URI]
$ aria2c -x2 [URI] # Split the task into two parts.
Run Aria2 as a Daemon
If we wish to use Aria2 as a download manager, we should run Aria2 as a daemon.
To start the Aria2 daemon:
$ aria2c --enable-rpc --rpc-listen-all
By default, Aria2 will perform 5 tasks at the same time, to change the
number of concurrent download tasks, we can specify the -j option:
$ aria2c --enable-rpc --rpc-listen-all -j[num-parallel]
For example, to download the files sequentially:
$ aria2c --enable-rpc --rpc-listen-all -j1
After starting the Aria2 daemon, click here for the Aria2 Web UI. You can add/remove the download tasks in the Aria2 Web UI.
Control Daemon with aria2rpc
Aria2 provides a command line tool, aria2rpc, to control the daemon.
However, it is not installed by default.
To obtain aria2rpc, run the following command:
$ cat /usr/share/doc/aria2/xmlrpc/aria2rpc.gz | gzip -d > aria2rpc
$ chmod +x aria2rpc
After these steps, move aria2rpc to your $PATH, so that we
can run aria2rpc directly.
Now, we can add a download task with:
$ aria2rpc addUri [URI] [options]
[task-id]
After adding a download task, an ID will be printed. We can remove a task with:
$ aria2rpc remove [task-id]
You may find more usages with:
$ aria2rpc --help
