aria2c Command: Tutorial & Examples

Download files using different protocols

aria2c is a free and open-source command-line download utility that supports downloading files from various protocols, including HTTP/HTTPS, FTP, BitTorrent, and Metalink. It is available for Linux, macOS, Windows, and Android.

Using aria2c, you can download files in parallel from multiple sources, significantly increasing your download speed. Additionally, aria2c supports resuming downloads that have been interrupted, which can be helpful if you have a slow or unreliable internet connection.

How aria2c works

aria2c operates by splitting files into multiple segments and downloading each segment from different sources simultaneously. This multi-source downloading allows for faster retrieval of data and can optimize bandwidth usage. By utilizing various protocols, aria2c can dynamically adjust to the best available sources, enhancing download efficiency.

What aria2c does

aria2c can download files from:

HTTP/HTTPS: For standard web downloads.
FTP: For traditional file transfer protocol downloads.
BitTorrent: For downloading files shared via the BitTorrent protocol.
Metalink: For downloading files with metadata that includes multiple sources.

What aria2c is used for

Common use cases for aria2c include:

Downloading large files quickly.
Resuming interrupted downloads.
Downloading files from multiple sources to improve speed.
Managing and organizing downloads through command-line interfaces.
Automating downloads through scripts, making it useful for system administrators and developers.

Why aria2c is important

aria2c is particularly valuable for users who work in environments where bandwidth is limited or unstable. Its ability to resume downloads and utilize multiple sources can save time and resources, making it an essential tool for system administrators and developers. Additionally, its command-line nature allows integration with other tools and scripts, enhancing productivity in automated environments.

How to use aria2c

Here are some examples of how to use aria2c with command-line parameters:

Download a file using HTTP/HTTPS:

aria2c https://example.com/myfile.zip

Download a file using FTP:

aria2c ftp://example.com/myfile.zip

Download a file using BitTorrent:

aria2c myfile.torrent

Download a file using Metalink:

aria2c myfile.metalink

Download a file in multiple parts (up to 16 parts by default):

aria2c -s16 http://example.com/myfile.zip

Set a download speed limit (in this example, 1MB/s):

aria2c --max-download-limit=1M http://example.com/myfile.zip

Save the downloaded file to a specific directory:

aria2c -d /path/to/directory http://example.com/myfile.zip

Use a proxy to download the file:

aria2c --http-proxy=http://proxy.example.com:8080 http://example.com/myfile.zip

Resume a previously interrupted download:

aria2c -c http://example.com/myfile.zip

Speed up file allocation, limit upload rate, and stop seeding after the download has finished:

aria2c --file-allocation=trunc --max-upload-limit=100K --seed-time=0 myfile.torrent

Sometimes you may want to download just a few files from a torrent link. First, find the index of the files using this command:

aria2c -S myfile.torrent

After that, you can select the files you need like this:

aria2c --select-file=6-8,10 myfile.torrent

Common command line parameters

-s: Specifies the number of connections per server (default is 1).
--max-download-limit: Sets a limit on download speed.
-d: Specifies the download directory.
-c: Resumes a previously interrupted download.
--http-proxy: Specifies an HTTP proxy for the download.

Potential problems and pitfalls

When using aria2c, users may encounter issues such as:

Network interruptions: Downloads can fail if the internet connection drops.
Proxy configuration errors: Incorrect proxy settings can prevent downloads.
File permissions: Ensure that the specified download directory has the necessary permissions.

Common errors and troubleshooting

If you encounter a "403 Forbidden" error, check the URL for proper access permissions.
A "File not found" error may indicate an incorrect URL or a deleted file.
Use --log-level=debug for more detailed output when troubleshooting.

Hacks and tricks

To increase download speed further, consider using aria2c with a script to automate downloads from multiple URLs.
Utilize the Metalink format to manage downloads more efficiently.
Combine aria2c with cron jobs for scheduled downloads, allowing for automated retrieval of files at specified intervals.

Tips and best practices

Always check the integrity of downloaded files, especially large ones, using checksums if available.
Use aria2c in scripts for automated downloading tasks, which can save time and reduce manual errors.
Regularly update aria2c to the latest version for optimal performance and security.
Monitor your downloads and their progress using the --show-console-readout option for better visibility during the process.