Download File

Download large files from HTTP/HTTPS URLs with resume support, progress monitoring, and timeout handling

📥 Large File Downloader

When to Use

Use this skill when downloading files from HTTP/HTTPS URLs, especially large files (>100MB).

Typical scenarios:

• Downloading software installers (DMG, EXE, ZIP)
• Downloading large datasets
• Downloading video/audio files
• Downloading documents/PDFs
• Any file download from URL

Trigger keywords:

• "download this file"
• "save this DMG"
• "download from this URL"
• "get this file"
• "帮我下载 xxx" (Chinese)

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Core Principles

⚠️ Must-Follow Best Practices

1. Always use background execution - Never run large downloads synchronously
2. Always set timeout - Configure reasonable timeout based on file size
3. Always support resume - Use curl -C - for resumable downloads
4. Always show progress - Use --progress-bar flag
5. Always verify results - Check file size after download completes

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Standard Process

Step 1: Start Download (Background Mode)

exec(
  command="curl -L -C - --progress-bar -o <destination_path> <URL>",
  background=true,
  timeout=600
)

Parameter explanation:

• -L - Follow redirects
• -C - - Resume partial download
• --progress-bar - Show progress bar
• -o - Output file path
• background=true - Critical! Run in background to avoid timeout
• timeout=600 - 10 minutes timeout (adjust based on file size)

Step 2: Monitor Progress

process(action="poll", sessionId="<session_id>")

Poll periodically to check download progress until completion.

Step 3: Verify Result

exec(command="ls -lh <file_path>")

Check:

• File exists
• File size is reasonable
• File is complete (compare MD5/SHA if available)

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Complete Examples

Example 1: Download DMG File (215MB)

User: "Download https://github.com/example/app/releases/download/v1.0/app.dmg"

Agent action:

{
  "tool": "exec",
  "command": "curl -L -C - --progress-bar -o ~/Downloads/app.dmg https://github.com/example/app/releases/download/v1.0/app.dmg",
  "background": true,
  "timeout": 600
}

Returns: {status: "running", sessionId: "xxx"}

Then poll periodically:

{
  "tool": "process",
  "action": "poll",
  "sessionId": "xxx"
}

After download completes, verify:

{
  "tool": "exec",
  "command": "ls -lh ~/Downloads/app.dmg && file ~/Downloads/app.dmg"
}

Example 2: Download Small File (<50MB)

For small files, simplified handling is acceptable:

exec(command="curl -L -o ~/Downloads/small.pdf https://example.com/small.pdf", timeout=120)

Small files can run synchronously, but still set timeout.

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Timeout Reference

File Size	Recommended Timeout
< 50MB	120 seconds (2 min)
50-200MB	300 seconds (5 min)
200-500MB	600 seconds (10 min)
500MB-1GB	1200 seconds (20 min)
> 1GB	1800 seconds (30 min) or more

---

Error Handling

Common Errors & Solutions

1. Download interrupted

# Re-run same command, curl -C - will resume automatically
curl -L -C - --progress-bar -o file.zip <URL>

2. Permission denied

# Ensure destination directory is writable
mkdir -p ~/Downloads

3. Redirect failed

# Use -L flag to follow redirects
curl -L -o file.zip <URL>

4. Network timeout

# Increase timeout or use --retry
curl -L --retry 3 --connect-timeout 30 -o file.zip <URL>

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Advanced Options

Multi-threaded Download (aria2)

If aria2 is available, use multi-threading for faster downloads:

exec(
  command="aria2c -x 16 -s 16 -k 1M --continue -o ~/Downloads/file.zip <URL>",
  background=true,
  timeout=600
)

Full Flow with Progress Monitoring

# 1. Start download
exec(command="curl -L -C - --progress-bar -o ~/Downloads/file.zip <URL>", background=true, timeout=600)

# 2. Poll every 30 seconds
process(action="poll", sessionId="xxx")

# 3. Verify after completion
exec(command="ls -lh ~/Downloads/file.zip")

# 4. Optional: Calculate checksum
exec(command="md5sum ~/Downloads/file.zip")

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Security Considerations

1. Download from trusted sources only - Verify URL origin
2. Check file type - Use file command to verify
3. Scan for viruses - If needed, scan after download
4. Don't overwrite important files - Check if destination exists

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Related Skills

• feishu-send-file - Send downloaded file to Feishu
• file-read - Read downloaded file content
• video-frames - Extract frames if video file

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Troubleshooting

If download fails, follow these steps:

1. Check network connectivity

   curl -I <URL>
   

2. Check disk space

   df -h ~/Downloads
   

3. View detailed error

   curl -v -o /dev/null <URL>
   

4. Try alternative tool

   wget --continue <URL>
   

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Remember: Always use background=true for large file downloads! 🎯