dl

A fast, reliable download manager that utilizes concurrent connections to maximize download speeds.

Features

• Concurrent downloading - Multiple connections for faster downloads
• Auto-resume by default - Automatically continues interrupted downloads
• Progress persistence - Tracks exact download state across restarts
• Sparse file support - Efficient disk usage on macOS/Linux
• Bandwidth limiting - Control download speed
• Checksum verification - Verify file integrity (MD5/SHA256)
• Smart retry logic - Exponential backoff for failed parts
• Configuration file - Save your preferred settings
• Graceful cancellation - Clean shutdown with Ctrl+C
• Progress tracking - Real-time progress with ETA

Install

Download (recommended)

Download the latest compiled release of dl from the releases page.

Compiling from source

Requirements: Go 1.23+

git clone https://github.com/mgomes/dl.git
cd dl
go build

Usage

Basic Usage

dl <file url> [file2 url] [file3 url] ...

Advanced Options

dl [options] <file url>

Options:
  -filename string     Custom filename for the download
  -boost int          Number of concurrent connections (default: 8)
  -retries int        Max retries for failed parts (default: 3)
  -resume             Resume interrupted download (default: true)
  -no-resume          Disable auto-resume functionality
  -limit string       Bandwidth limit (e.g. 1M, 500K, 100KB/s)
  -checksum string    Verify with checksum (format: algorithm:hash)

Examples

# Basic download
dl https://example.com/file.zip

# Download with custom filename
dl -filename myfile.zip https://example.com/file.zip

# Downloads auto-resume by default (just re-run the same command)
dl https://example.com/file.zip

# Disable auto-resume for a fresh download
dl -no-resume https://example.com/file.zip

# Limit bandwidth to 1 MB/s
dl -limit 1M https://example.com/file.zip

# Verify download with SHA256
dl -checksum sha256:abc123... https://example.com/file.zip

# Use 4 connections with 5 retries
dl -boost 4 -retries 5 https://example.com/file.zip

# Combine multiple options
dl -boost 4 -limit 500K -filename data.tar.gz https://example.com/file.tar.gz

Configuration File

Create a .dlrc file in your home directory to set default values:

# ~/.dlrc
boost = 8
retries = 3

Advanced Features

Concurrent Downloads

The -boost parameter controls how many simultaneous connections are used. Higher values aren't always better - your network throughput will eventually saturate. The default of 8 works well for most scenarios.

Auto-Resume Capability

Downloads now automatically resume by default! If a download is interrupted (network failure, Ctrl+C, system crash), simply run the same command again:

# Start a download
dl https://example.com/large-file.zip
# ... download interrupted at 45% ...

# Just run the same command to resume
dl https://example.com/large-file.zip
# Output: Resuming download using progress file (45.0% complete)

Features:

• Automatic detection - Finds incomplete downloads and resumes automatically
• Progress persistence - Saves exact download state in .filename.dl_progress files
• Multi-part awareness - Resumes each parallel connection from exact byte position
• Sparse file support - Efficient disk usage on macOS/Linux filesystems
• Smart validation - Verifies same URL/filesize before resuming
• Clean completion - Removes progress files after successful download

Progress tracking details:

• Progress saved every 2 seconds during download
• Each download part tracked individually
• Survives crashes, network failures, and interruptions
• Works with multi-connection downloads (preserves boost setting)

To force a fresh download without resuming:

dl -no-resume https://example.com/file.zip

The tool shows clear status messages:

Resuming download using progress file (73.2% complete)
Part 0 already completed, skipping
Part 1 already completed, skipping
Downloading: 45.23 MB / 128.45 MB [=========>--------] 73.2% 3.2 MB/s 00:27

Bandwidth Limiting

Control download speed with -limit:

• 1M or 1MB = 1 megabyte per second
• 500K or 500KB = 500 kilobytes per second
• 100KB/s = 100 kilobytes per second

When using multiple connections, the bandwidth is divided equally among all connections.

Checksum Verification

Verify file integrity after download:

dl -checksum sha256:e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 https://example.com/file.zip
dl -checksum md5:d41d8cd98f00b204e9800998ecf8427e https://example.com/file.zip

Supported algorithms: md5, sha256

Error Handling

dl includes robust error handling:

• Exponential backoff - Failed parts are retried with increasing delays (1s, 2s, 4s)
• Configurable retries - Set max retry attempts with -retries
• Context-aware errors - Clear error messages with relevant details
• Graceful shutdown - Ctrl+C cleanly cancels downloads

Technical Details

• Uses HTTP/HTTPS with proper timeout configuration
• Connection pooling for efficient resource usage
• Progress tracking with real-time speed and ETA
• Smart chunk boundary calculation for optimal performance
• Rate limiting with context-aware cancellation