Using cURL for Fast and Reliable Downloads
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Using cURL for Fast and Reliable Downloads

Publish Date: May 26
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If you want to fetch files quickly, automate downloads, or test web servers, cURL is the tool to use. It works on all major platforms including Windows, Mac, and Linux, and can handle everything from simple downloads to complex scripts. Mastering using cURL requires understanding its finer details, and we are here to guide you through the process step by step.

Master File Naming

By default, cURL doesn’t save files to disk. It streams content right into your terminal window. So, if you want the file, you’ve got to tell it where to go.

Save with a custom filename:

curl -o test.html https://example.com
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This grabs the webpage and saves it as test.html in your current folder.

Want to save somewhere else? Just specify the path:

curl -o ~/Downloads/test.html https://example.com
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Heads-up: If the file already exists, it gets overwritten — no warning. To avoid accidental overwrites, try this:

if [ -f file.txt ]; then
    echo "File already exists!"
else
    curl -O https://example.com/file.txt
fi
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This little script checks for the file first, then downloads only if it's missing. Simple safeguard. Always worth it.

Dealing with Redirects

Many download links redirect you behind the scenes. Browsers handle it automatically, but cURL needs a nudge:

curl -L -o test.zip https://example.com/download
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The -L flag tells cURL to follow redirects until it hits the real file. Without it? You’ll download the redirect page instead of the file itself.

Why does this matter?

Shortened URLs (Bit.ly, TinyURL) rely on redirects.
Many sites forward HTTP → HTTPS for security.
Some servers gate downloads behind redirects for control.

Too many redirects? Limit them:

curl -L --max-redirs 5 -o file.zip https://example.com/download
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If the redirect count hits your limit, cURL stops and warns you. Smart.

Downloading Multiple Files Like a Pro

For any OS:

Just stack multiple -O flags:

curl -O https://example.com/file1.zip -O https://example.com/file2.zip
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Or use brace expansion for sequential files:

curl -O https://example.com/file{1,2,3}.zip
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Windows PowerShell:

Download from a list in urls.txt:

Get-Content urls.txt | ForEach-Object { curl -O $_ }
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Loop for numbered files:

For ($i=1; $i -le 3; $i++) { curl -O "https://example.com/file$i.zip" }
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Linux / macOS Terminal:

From a file:

xargs -n 1 curl -O < urls.txt
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Loop for numbered files:

for i in {1..5}; do 
  curl -O https://example.com/file$i.zip 
done
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Manage Your Bandwidth

Downloading massive files over shaky or limited networks? Use --limit-rate to cap your speed.

curl --limit-rate 500k -O https://example.com/archive.zip
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This limits the download to 500 KB/s. Why bother? Because throttling reduces connection drops, avoids server blocks, and saves mobile data.

You can combine this with batch downloads:

Windows PowerShell:

1..3 | ForEach-Object { curl --limit-rate 500k -O https://example.com/archive$_.zip }
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Linux/macOS Bash:

for i in {1..3}; do 
  curl --limit-rate 500k -O https://example.com/archive$i.zip 
done
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Silent Downloads and Error Handling

By default, cURL chatters away showing progress and speed. Need silence? Use:

curl -s -O https://example.com/file.zip
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Want silent mode but still see errors?

curl -s -S -O https://example.com/file.zip
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Perfect for scripts where you only want to catch issues without clutter.

Authentication

Many protected files or APIs need credentials. cURL supports them all.

Username + password:

curl -u username:password -O https://example.com/protected-file.zip
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If your password has special characters, quote it:

curl -u username:"p@ss#word!" -O https://example.com/protected-file.zip
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If you omit the password, cURL will prompt you interactively.

Using access tokens (Bearer tokens):

curl -H "Authorization: Bearer your_token_here" -O https://api.example.com/data.json
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Proxy Support

Working behind a corporate firewall or need anonymity? Use a proxy.

Basic syntax:

curl -x http://proxy.server:port -o file.zip https://example.com/archive.zip
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With proxy authentication:

curl -x http://proxy.example.com:80 -U user:password -o archive.zip https://example.com/archive.zip
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For SOCKS proxies:

curl --proxy socks5h://proxy.example.com:1080 -o archive.zip https://example.com/archive.zip
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socks5h is safer because DNS queries go through the proxy, hiding your traffic better.

Track Your Download

Want a sleek progress bar instead of cluttered percentages?

curl -# -o file.zip https://example.com/file.zip
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For detailed debugging info:

curl -v -o file.zip https://example.com/file.zip
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After the download finishes, show speed stats:

curl -o file.zip -w "Download speed: %{speed_download} bits per second\n" https://example.com/file.zip
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This is gold when diagnosing slow or flaky connections.

Know Your Requests and Responses

Use verbose mode to peek behind the curtain:

curl -v -o file.zip https://example.com/archive.zip
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You’ll see:

Server IP and connection setup
HTTP requests sent
Status codes (200, 301, 404, etc.)
Response headers (content type, caching, etc.)

This helps pinpoint problems before wasting time on downloads.

Wrapping Up

cURL is a powerful command-line downloader known for its speed and flexibility. It offers features like precise file naming, redirect handling, multiple downloads, bandwidth control, authentication, proxy support, and progress tracking. Whether running simple scripts or building complex pipelines, cURL adapts to your needs as a trusted tool for managing web resources.

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