Mastering aria2: Fast, Lightweight Command-Line Download Tool

Introduction

aria2 is a lightweight, high‑efficiency command‑line download utility that supports HTTP(S), FTP, BitTorrent and Metalink. It maximises bandwidth utilisation by downloading from multiple sources concurrently and can verify file integrity using Metalink hashes.

Key Features

Concurrent multi‑protocol downloading

Multiple source URLs per file

Automatic integrity checking via Metalink

Intelligent piece selection and adaptive re‑splitting

Installation

# Ubuntu
sudo apt-get install aria2

# CentOS
sudo yum install aria2

Basic Usage

Official manual: https://aria2.github.io/manual/en/html/index.html

Download a single file

aria2c "https://example.com/file.zip"

Download multiple files

aria2c -Z "https://example.com/file1.zip" "https://example.com/file2.zip"

Expand URL patterns

aria2c -Z -P "https://example.com/image{1,2,3}_{A,B,C}.png"

Specify output filename

aria2c -o myfile.zip "https://example.com/file.zip"

Resume interrupted downloads

aria2c -c "https://example.com/file.zip"

Set number of connections per server

aria2c -x 8 "https://example.com/file.zip"

Set maximum parallel connections per file

aria2c -s 8 "https://example.com/file.zip"

Set maximum parallel download tasks

aria2c -Z -j 8 "https://example.com/file1.zip" "https://example.com/file2.zip"

Read URLs from a file

aria2c -i download_list.txt

Download to a specific directory

aria2c -d /path/to/dir "https://example.com/file.zip"

Limit download speed

aria2c --max-download-limit=500k "https://example.com/file.zip"

Advanced Operations

Download a BitTorrent torrent file

aria2c "https://example.com/file.torrent"

Download via magnet link

aria2c "magnet:?xt=urn:btih:YOUR_HASH"

List files in a magnet link

aria2c -S "magnet:?xt=urn:btih:YOUR_HASH"

Select specific files from a torrent

aria2c --select-file=1,3 "https://example.com/file.torrent"
aria2c --select-file=1-3,5 "https://example.com/file.torrent"

Configuration File Overview

Common options for ~/.aria2/aria2.conf (default values shown). Adjust as needed.

# Download directory
 dir=

# Log file path ("-" for stdout)
 log=

# Maximum concurrent downloads
 max-concurrent-downloads=5

# Enable integrity check (BT/Metalink)
 check-integrity=false

# Continue partially downloaded files
 continue=true

# Proxy settings (all protocols)
 all-proxy=
 all-proxy-user=
 all-proxy-passwd=

# Connection timeout (seconds)
 connect-timeout=60

# Enable DHT (IPv4)
 enable-dht=true

# Enable peer exchange
 enable-peer-exchange=true

# Maximum overall download speed (0 = unlimited)
 max-overall-download-limit=0

# Maximum per‑task download speed (0 = unlimited)
 max-download-limit=0

# Piece length for HTTP/FTP downloads
 piece-length=1M

# Enable colour output in terminal
 enable-color=true

# Enable async DNS resolution
 async-dns=true

# Enable RPC server (disabled by default)
 enable-rpc=false
 rpc-listen-port=6800

# Save session file path
 save-session=
 save-session-interval=0

# Enable HTTP keep‑alive
 enable-http-keep-alive=true

# Enable HTTP pipelining
 enable-http-pipelining=false

# Accept GZip encoding
 http-accept-gzip=false

# Verify SSL/TLS certificates
 check-certificate=true

# User‑agent string
 user-agent=aria2/$VERSION

Helpful Tips

Wrap URLs containing special characters (e.g., &, *) in single or double quotes.

Use -h to search options, e.g., aria2c -h connection.

For large files, increase piece-length and adjust max-connection-per-server to improve throughput.

Enable async-dns to reduce DNS lookup latency.