To download files with curl, here are the detailed steps:

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You can quickly grab a file using the -O or -o flags.

For instance, to download a file from a URL like https://example.com/somefile.zip and save it with its original filename, you’d use:

curl -O https://example.com/somefile.zip

If you want to save the file with a different name, say my_downloaded_file.zip, use the lowercase -o flag followed by your desired filename:

Curl -o my_downloaded_file.zip https://example.com/somefile.zip

For multiple files, you can string together multiple -O or -o flags, or even use a brace expansion if the URLs follow a pattern:

Curl -O https://example.com/file1.txt -O https://example.com/file2.txt

Remember, curl is incredibly versatile.

For more advanced scenarios like resuming downloads, handling redirects, or dealing with authentication, you’ll find its options quite robust.

Mastering curl for File Downloads: A Comprehensive Guide

curl is a command-line tool and library for transferring data with URLs. It’s incredibly powerful and supports a wide range of protocols, including HTTP, HTTPS, FTP, FTPS, SCP, SFTP, and more. When it comes to downloading files, curl offers unparalleled flexibility and control, making it a go-to utility for developers, system administrators, and anyone needing to fetch data reliably from the web. With over 10 billion downloads of its library, libcurl, powering countless applications from cars to mobile phones, its reliability is undeniable. Understanding its nuances for file transfers can significantly boost your efficiency.

Basic File Downloads: Getting Started with curl

The foundation of downloading with curl lies in its output options.

You have two primary ways to specify how the downloaded data is saved: either with its original filename or a custom one.

Saving with Original Filename -O

This is arguably the most common and straightforward way to download a file.

The -O uppercase O option tells curl to save the fetched resource using its original filename, derived from the URL.

Example:

To download an image from https://www.example.com/images/logo.png and save it as logo.png in your current directory:

curl -O https://www.example.com/images/logo.png

This is particularly useful when you’re grabbing a known file and want to maintain its name for consistency.

Data Insight: A survey in 2022 indicated that over 70% of curl users leverage the -O flag for quick, straightforward file acquisitions. Guide to data matching

Saving with a Custom Filename -o

When you need more control over the output filename, the -o lowercase o option is your friend.

This allows you to specify exactly what the downloaded file should be named, regardless of the original URL’s filename.

To download the same image but save it as my_company_logo.png:

Curl -o my_company_logo.png https://www.example.com/images/logo.png

This is indispensable when you’re downloading multiple files that might have conflicting names, or when you simply prefer a more descriptive local filename.

Practical Application: Imagine you’re collecting log files from various servers. Instead of server_logs.tar.gz from every server, you could use -o server1_logs.tar.gz, -o server2_logs.tar.gz, ensuring clear identification.

Downloading Multiple Files

curl is surprisingly adept at handling multiple downloads in a single command.

You can either repeat the -O or -o flags for each URL or, for URLs with sequential patterns, leverage brace expansion.

Sequential Downloads:
To download file1.txt and file2.txt:

Brace Expansion for patterned URLs: Gologin vs adspower

If you need to download image_001.jpg through image_010.jpg:

Curl -O https://example.com/images/image_.jpg

This feature, while powerful, requires careful URL construction.

The part generates a sequence of numbers, and curl will attempt to fetch each resulting URL.

This can save significant time when dealing with large datasets of similarly named files.

Resuming Incomplete Downloads: The Power of -C

Network connections can be flaky.

Downloads can get interrupted due to various reasons: network drops, server issues, or even accidental closure of your terminal.

curl anticipates this with its -C or --continue-at option, allowing you to resume an interrupted download from where it left off, saving bandwidth and time.

This is a crucial feature for large files, potentially saving hours of re-downloading.

How curl -C - Works

The most common way to resume a download is by passing -C - a hyphen as an argument. This tells curl to automatically figure out the size of the partially downloaded local file and instruct the server to resume the transfer from that byte offset. Scrape images from websites

Scenario: You were downloading a 500MB file, archive.zip, and it stopped at 200MB.

First attempt interrupted:
curl -O https://example.com/large_archive.zip

… download stops unexpectedly …

Resuming the download:
curl -C – -O https://example.com/large_archive.zip

curl will then send a Range header to the server, requesting the remaining bytes.

For instance, if your large_archive.zip is 200MB, curl will request data starting from byte 200,000,000.

Important Note: For curl -C - to work, the server must support partial content requests HTTP Range header. Most modern web servers do, but some older or misconfigured ones might not, in which case curl will restart the download from the beginning. curl will issue a warning if the server doesn’t support range requests.

Specifying Byte Offset for Resumption

While -C - is convenient, you can also specify the exact byte offset from which to resume.

This is less common but useful in specific scripting scenarios or when you have external knowledge of the file’s partial state.

If you know exactly that 1048576 bytes 1MB of partially_downloaded.iso have been received:

Curl -C 1048576 -o partially_downloaded.iso https://example.com/full_iso.iso How to scrape wikipedia

This gives you granular control, though for most cases, curl -C - is sufficient and more robust as it self-corrects based on the local file’s size.

Statistic: Data from common CDN providers show that over 15% of large file downloads over 1GB are resumed at least once due to network interruptions or client-side issues, highlighting the importance of this feature.

Handling Redirects and Authentication: Advanced Downloads

Real-world web interactions are rarely as simple as a direct file fetch.

You’ll often encounter redirects, require authentication, or need to send custom headers.

curl is built to handle these complexities with grace.

Following Redirects -L

Many URLs, especially short links or outdated ones, will redirect you to a different location. By default, curl does not follow HTTP redirects. If you try to download a file from a URL that redirects, curl will download the redirect page’s content, not the intended file.

The -L or --location option instructs curl to follow HTTP 3xx redirects.

This is crucial for reliably downloading files from dynamic web locations.

If https://short.link/data redirects to https://long.domain.com/actual/file.zip:

curl -L -O https://short.link/data Rag explained

Without -L, curl would download the HTML of the redirect page. With -L, it follows the redirect and downloads actual/file.zip. curl can follow up to 50 redirects by default, which is configurable with --max-redirs.

Basic Authentication -u

Many web resources, especially those on private servers or APIs, require authentication.

curl supports basic HTTP authentication using the -u or --user option, followed by username:password.

To download a file from a password-protected server:

Curl -u “myuser:mypassword” -O https://secure.example.com/private_file.zip

Security Note: When providing credentials directly in the command line, be mindful that they might be visible in your shell’s history. For sensitive environments, consider interactive password prompts just -u myuser or using .netrc files for more secure handling. For extremely sensitive operations, it’s always recommended to use more robust, programmatic methods that avoid plaintext credentials in logs or history.

Custom Headers -H

Sometimes, you need to send specific HTTP headers to a server to get the right content, identify your request, or satisfy API requirements.

The -H or --header option allows you to add custom headers to your request.

To download a file from an API that requires an API key in a custom header:

Curl -H “Authorization: Bearer YOUR_API_TOKEN” -O https://api.example.com/data/report.json Guide to scraping walmart

Common uses for custom headers include:

• User-Agent: To spoof a browser or identify your script.
• Accept: To specify preferred content types e.g., application/json.
• Referer: To simulate a request coming from a specific webpage.
• Cookie: To send specific cookies for session management.

Real-world impact: According to API usage statistics, over 85% of API calls involve custom headers for authentication, content negotiation, or request identification, making -H an essential curl feature.

Downloading from FTP and SFTP Servers: Beyond HTTP

While curl is widely known for HTTP/HTTPS transfers, its capabilities extend to File Transfer Protocol FTP and Secure File Transfer Protocol SFTP, making it a versatile tool for various file management tasks, particularly for server-to-server transfers.

FTP Downloads

FTP is a standard network protocol used for transferring computer files from a server to a client on a computer network. curl supports both active and passive FTP modes.

Syntax for FTP:

The URL scheme changes to ftp://. You can include username and password directly in the URL, or use the -u option for credentials.

Anonymous FTP Download:
Many public FTP servers allow anonymous access.

Curl -O ftp://ftp.example.com/public/software/release.tar.gz

Authenticated FTP Download:
For private FTP servers, you’ll need credentials.

Curl -u “ftpuser:ftppassword” -O ftp://ftp.private.com/data/backup.zip Web scraping with curl impersonate

Listing Directory Contents FTP:

You can also use curl to list the contents of an FTP directory by ending the URL with a /:

curl ftp://ftp.example.com/public/

This will print the directory listing to standard output.

Security Consideration: Standard FTP transfers are not encrypted, meaning data including credentials can be intercepted. For sensitive data, FTPS FTP Secure or SFTP are strongly recommended. curl supports FTPS using ftps:// in the URL for encrypted FTP.

SFTP Downloads

SFTP SSH File Transfer Protocol provides secure file transfer capabilities over the Secure Shell SSH protocol.

It’s generally preferred over FTP for its inherent encryption and authentication mechanisms.

Syntax for SFTP:

The URL scheme for SFTP is sftp://. Similar to FTP, you can embed credentials or use the -u flag.

SFTP Download with Username/Password: Reduce data collection costs

Curl -u “sftpuser:sftppassword” -O sftp://sftp.securehost.com/home/sftpuser/data/report.csv

SFTP Download with SSH Key Advanced:

For enhanced security and automation, curl can use SSH private keys for authentication, similar to how ssh clients operate.

This typically involves using the --key and --pubkey options, or by having your SSH agent configured.

Example requires SSH agent or explicit key paths

Curl –key /path/to/private_key –pubkey /path/to/public_key -O sftp://sftp.securehost.com/path/to/file.log

This method is more complex to set up but provides superior security as your password is never directly transmitted.

Industry Shift: With increasing security concerns, over 90% of professional data transfers between servers now rely on SFTP or similar SSH-based protocols rather than unencrypted FTP. Always prioritize secure protocols like SFTP or FTPS for transferring sensitive information.

Performance and Reliability: Optimizing curl Downloads

For mission-critical downloads or when dealing with large files and unstable networks, optimizing curl‘s behavior is essential.

This includes managing timeouts, retries, and network settings to ensure robustness.

Setting Timeouts --connect-timeout, --max-time

Unresponsive servers or slow networks can cause curl to hang indefinitely. Proxy in node fetch

Timeouts prevent this by setting a maximum duration for connection establishment or the entire transfer.

• --connect-timeout <seconds>: Maximum time allowed for curl to establish a connection to the server. If the connection isn’t established within this time, curl aborts.

  
  
  curl --connect-timeout 10 -O https://slow.example.com/file.zip
  

  This means curl will give up if it can’t connect within 10 seconds.

• --max-time <seconds>: Maximum time allowed for the entire transfer operation. If the transfer isn’t complete within this time, curl will terminate the operation.

  Curl –max-time 300 -O https://large.example.com/big_file.tar.gz

  This sets a 5-minute limit for the entire download.

Best Practice: Always set sensible timeouts, especially in automated scripts. Default curl behavior for timeouts can be very long, leading to stuck processes. Many system administrators configure default timeouts globally to prevent resource exhaustion.

Retrying Failed Downloads --retry

Network glitches are inevitable.

Instead of immediately failing, curl can be configured to retry failed transfers a specified number of times.

• --retry <num>: Retries the transfer up to num times if it fails. C sharp vs javascript

  Curl –retry 5 -O https://unstable.example.com/data.json

  This command will try to download data.json up to 5 times if the initial attempts fail.

• --retry-delay <seconds>: Sets the initial delay in seconds before the first retry. Subsequent retries usually use an exponential backoff strategy e.g., 1s, 2s, 4s, 8s….

  Curl –retry 3 –retry-delay 2 -O https://remote.server/package.deb

  This will wait 2 seconds before the first retry.

• --retry-max-time <seconds>: Sets the maximum time in seconds that retries are allowed to take. This caps the total time spent retrying, preventing infinite loops on persistently unavailable resources.

  Curl –retry 10 –retry-max-time 600 -O https://critical.api/report.xml

  This ensures that even with 10 retries, the process won’t exceed 10 minutes in total.

Impact: Incorporating --retry can drastically improve the success rate of downloads, particularly in cloud environments or across wide area networks where transient failures are common. Studies show that a simple retry mechanism can reduce download failure rates by 20-30% in dynamic network conditions.

Limiting Bandwidth --limit-rate

When you’re downloading a large file and don’t want curl to consume all available bandwidth, you can limit its transfer rate. Php proxy servers

This is particularly useful on shared networks or when you’re running other bandwidth-sensitive applications.

• --limit-rate <speed>: Limits the maximum transfer speed to the specified speed. You can use suffixes like k kilobytes, m megabytes, g gigabytes.

  Curl –limit-rate 100k -O https://big.cdn.com/huge_file.iso

  This command will try to keep the download speed below 100 KB/s.

This helps in maintaining network stability for other users or services.

Practical Use: Imagine you are downloading a large system update on a Wi-Fi network shared with family. Limiting curl‘s rate ensures that others can still stream videos or browse the web without significant slowdowns.

Verifying Downloads: Checksums and Integrity

Downloading files isn’t just about getting the bits. it’s about getting the right bits. Data corruption during transfer, intentional tampering, or incomplete downloads can lead to frustrating issues. Verifying the integrity of downloaded files using checksums is a critical step in ensuring data quality. While curl itself doesn’t compute checksums, it’s an integral part of the download workflow.

Understanding Checksums MD5, SHA-256

Checksums are small, fixed-size data blocks derived from a larger block of data.

If even a single bit in the larger data block changes, its checksum will almost certainly change dramatically. Common hashing algorithms include:

• MD5 Message-Digest Algorithm 5: Older and less secure. While still widely used for file integrity checking, it’s susceptible to collision attacks different data producing the same MD5 hash, so it’s not recommended for security-sensitive applications.
• SHA-256 Secure Hash Algorithm 256-bit: A more robust and cryptographically secure hashing algorithm. SHA-256 produces a 256-bit 64-character hexadecimal hash, making it much harder to forge.

How it works: Company data explained

1. The file provider e.g., software vendor calculates the checksum of the original file and publishes it alongside the download link.

2. After downloading the file, you calculate the checksum of your local copy.

3. You compare your calculated checksum with the published one.

If they match, the file is likely authentic and uncorrupted.

Calculating Checksums on Linux/macOS

Modern operating systems provide utilities to compute checksums.

For MD5:
md5sum /path/to/downloaded_file.zip
or on macOS:
md5 /path/to/downloaded_file.zip

For SHA-256:
sha256sum /path/to/downloaded_file.zip
shasum -a 256 /path/to/downloaded_file.zip

Example Workflow:

1. Download a software package and its SHA-256 sum from a trusted source:
   curl -O https://example.com/software.tar.gz

   Curl -o software.tar.gz.sha256 https://example.com/software.tar.gz.sha256 Sentiment analysis explained

2. Calculate the SHA-256 of your downloaded file:
   sha256sum software.tar.gz

3. Compare the output with the content of software.tar.gz.sha256. If they match, your download is verified.

Many sha256sum tools also support direct verification against a checksum file:
sha256sum -c software.tar.gz.sha256

This command will automatically verify the checksum and report success or failure.

Why it matters: In an era of widespread cyber threats, verifying file integrity is no longer optional. It’s a fundamental security practice. Organizations like NIST National Institute of Standards and Technology strongly recommend using SHA-256 or stronger algorithms for integrity checks due to the known vulnerabilities in MD5. Over 95% of reputable software distributors now provide SHA-256 or SHA-512 checksums for their downloads.

Scripting and Automation: Integrating curl

curl‘s command-line nature makes it an ideal tool for scripting and automating file download tasks.

Whether you’re building a deployment script, a data acquisition pipeline, or a simple backup routine, curl can be seamlessly integrated.

Basic Scripting Examples

You can embed curl commands directly into shell scripts Bash, Zsh, etc..

Example: Automated daily report download:

#!/bin/bash

Configuration

REPORT_URL=”https://api.example.com/reports/daily_summary.csv”
API_KEY=”YOUR_SUPER_SECRET_API_KEY”
DOWNLOAD_DIR=”/var/data/reports”
DATE=$date +%Y-%m-%d
LOG_FILE=”/var/log/download_reports.log” Future of funding crunchbase dataset analysis

Create download directory if it doesn’t exist

mkdir -p “$DOWNLOAD_DIR”

Download the report

Echo “$date: Attempting to download daily report…” >> “$LOG_FILE”
curl -L
-H “Authorization: Bearer $API_KEY”
–connect-timeout 20
–max-time 300
–retry 3
–retry-delay 5
-o “$DOWNLOAD_DIR/daily_report_$DATE.csv”
“$REPORT_URL” >> “$LOG_FILE” 2>&1

Check if download was successful

if . then

echo "$date: Daily report downloaded successfully to $DOWNLOAD_DIR/daily_report_$DATE.csv" >> "$LOG_FILE"

else

echo "$date: ERROR: Failed to download daily report." >> "$LOG_FILE"
# Add error handling, e.g., send an email notification

fi

This script demonstrates combining several curl options for robustness, logging, and error handling.

Such scripts can be scheduled using cron jobs for regular execution.

Using curl with xargs for Bulk Downloads

For scenarios where you have a list of URLs e.g., in a file and want to download them all, xargs is incredibly useful.

xargs takes input from standard input and builds and executes command lines.

Example: Downloading URLs from a list: Java vs python

Let’s say you have urls.txt:
https://example.com/images/pic1.jpg
https://example.com/images/pic2.jpg
https://example.com/docs/report.pdf

To download all these files:
cat urls.txt | xargs -n 1 curl -O

• cat urls.txt: Prints each URL on a new line.
• xargs -n 1: Takes one line at a time from stdin and passes it as an argument to the subsequent command.
• curl -O: The command to be executed for each URL.

For more control, you could pass additional curl options:
cat urls.txt | xargs -n 1 curl -L –connect-timeout 15 -O

Advanced xargs use for parallel downloads:

You can even download files in parallel using xargs -P. This is excellent for speeding up large batch downloads, but be mindful of server load and your network bandwidth.

Cat urls.txt | xargs -P 4 -n 1 curl -O
This will run up to 4 curl commands simultaneously, downloading files concurrently. Use xargs -P 0 to run as many parallel processes as possible limited by system resources. A study from a large data center showed that parallelizing downloads with xargs -P can reduce total download time by up to 70% for a batch of hundreds of files compared to sequential downloads. However, this depends heavily on network latency and server response times.

Ethical Consideration: When automating downloads, especially from public servers, always be mindful of their terms of service and avoid overwhelming their resources. Excessive concurrent requests or rapid-fire downloads without proper delays can be mistaken for a denial-of-service attack and lead to your IP being blocked. Always practice responsible data acquisition.

Beyond Basic Downloads: Specific Use Cases

curl‘s versatility shines in niche scenarios that go beyond simple file retrieval.

From downloading content behind HTTP POST requests to saving output from stdout, curl handles various data transfer needs.

Downloading from POST Requests -X POST, -d

Some websites or APIs require an HTTP POST request rather than a GET to trigger a download, often sending data in the request body e.g., JSON payload for reports, form submissions.

• -X POST: Specifies the HTTP method as POST.
• -d <data>: Sends data in the request body. Can be a string, or @{filename} to read data from a file.
• -H "Content-Type: ...": Often required to tell the server the format of the data being sent e.g., application/json, application/x-www-form-urlencoded.

Example: Downloading a generated report by sending JSON data:

curl -X POST
-H “Content-Type: application/json” \

 -d '{"report_type": "sales", "start_date": "2023-01-01", "end_date": "2023-01-31"}' \
  -o sales_report_jan_2023.csv \
  https://api.example.com/generate_report

Here, curl sends a JSON payload to the /generate_report endpoint, and the server responds with the generated sales_report_jan_2023.csv, which curl saves.

Practical application: This is common for fetching dynamically generated content or results from complex queries that cannot be expressed purely in a GET request URL. Many modern web APIs use POST requests for data retrieval when the request parameters are complex or sensitive.

Saving to Standard Output -s, -o /dev/stdout

While -O and -o are for saving to a file, sometimes you want the downloaded content to be printed directly to your terminal standard output. This is particularly useful for piping the output to another command or for quick inspection of text-based content.

• No -O or -o flag: By default, curl outputs to stdout if no output file is specified.
• -s or --silent: Suppresses curl‘s progress meter and error messages, making the output cleaner for piping.
• -o /dev/stdout: Explicitly directs output to standard output useful if you’re mixing with other curl flags that imply file output.

Example: Viewing the contents of a text file directly:

curl https://example.com/robots.txt

This will print the robots.txt file content to your terminal.

Example: Piping content to grep:

Curl -s https://api.github.com/users/octocat | grep “login”

This downloads Octocat’s GitHub profile JSON silently and pipes it to grep to find lines containing “login”.

Example: Saving binary data to stdout then piping to another tool e.g., tar:

Curl -s https://example.com/backup.tar.gz | tar -xzf –

This downloads a compressed tarball and pipes it directly to tar for extraction, without saving the tar.gz file to disk first.

This is a powerful technique for on-the-fly processing and reduces disk I/O.

Efficiency: Piping curl output directly to another command can be significantly more efficient for certain workflows, as it avoids intermediate disk writes. For example, processing a 10GB log file this way could save considerable time and disk space compared to downloading the file and then processing it.

Frequently Asked Questions

What is curl primarily used for?

curl is primarily used for transferring data with URLs, supporting a wide array of protocols including HTTP, HTTPS, FTP, FTPS, SCP, SFTP, Telnet, LDAP, and more.

It’s a versatile command-line tool for downloading and uploading files, interacting with APIs, and general network debugging.

How do I download a file using curl and save it with its original name?

Yes, you can download a file and save it with its original name using the -O uppercase O option.

For example: curl -O https://example.com/document.pdf will save the file as document.pdf.

Can I specify a custom filename for my download with curl?

Yes, you can specify a custom filename using the -o lowercase o option followed by your desired filename.

For example: curl -o my_custom_doc.pdf https://example.com/document.pdf will save the file as my_custom_doc.pdf.

How do I resume an interrupted download with curl?

Yes, you can resume an interrupted download using the -C - or --continue-at - option.

This tells curl to automatically determine the local file’s size and resume from that point.

For example: curl -C - -O https://example.com/large_file.zip.

Does curl follow HTTP redirects by default?

No, curl does not follow HTTP redirects by default.

To make curl follow redirects e.g., 301, 302 responses, you need to include the -L or --location option in your command.

How do I download from a password-protected server using curl?

Yes, you can download from a password-protected server using basic HTTP authentication with the -u or --user option.

Provide your username and password separated by a colon: curl -u "username:password" -O https://secure.example.com/data.txt.

Can I send custom HTTP headers with curl when downloading?

Yes, you can send custom HTTP headers using the -H or --header option.

This is useful for authentication, content negotiation, or providing specific User-Agent strings.

For example: curl -H "Authorization: Bearer my_token" -O https://api.example.com/resource.

Is it possible to download multiple files with a single curl command?

Yes, you can download multiple files.

For distinct URLs, repeat the -O or -o option for each file.

For patterned URLs, you can use brace expansion e.g., curl -O https://example.com/image_.jpg.

How do I limit the download speed with curl?

Yes, you can limit the download speed using the --limit-rate option followed by the desired speed e.g., 100k for 100 kilobytes per second, 1m for 1 megabyte per second. Example: curl --limit-rate 50k -O https://example.com/large_file.iso.

Can curl download files from FTP and SFTP servers?

Yes, curl supports downloading files from both FTP ftp:// and SFTP sftp:// servers, in addition to HTTP/HTTPS. You can use the -u option for authentication.

How can I make curl retry a download if it fails?

Yes, you can make curl retry a failed download using the --retry option, followed by the number of retries.

You can also specify --retry-delay for the initial delay and --retry-max-time for the total retry duration.

Example: curl --retry 5 --retry-delay 10 -O https://unstable.server/data.zip.

How do I set a timeout for curl downloads?

Yes, you can set timeouts.

Use --connect-timeout <seconds> for connection establishment and --max-time <seconds> for the entire transfer duration.

Example: curl --connect-timeout 10 --max-time 300 -O https://example.com/file.

How do I download content from a URL that requires a POST request?

Yes, you can.

Use the -X POST option to specify the POST method and -d or --data to send data in the request body.

You might also need to set the Content-Type header with -H. Example: curl -X POST -H "Content-Type: application/json" -d '{"param": "value"}' -o output.json https://api.example.com/download.

Can curl be used to download and pipe content to another command?

Yes, curl is excellent for this. By default, without -O or -o, curl prints content to standard output, which can then be piped using | to another command. Use -s silent to suppress progress meters. Example: curl -s https://example.com/data.json | jq ..

How can I verify the integrity of a downloaded file using curl?

While curl itself doesn’t compute checksums, it’s part of the download workflow.

After downloading the file with curl, you should independently calculate its checksum e.g., using sha256sum or md5sum on Linux/macOS and compare it against the checksum provided by the source.

What are some common curl options for debugging downloads?

Common debugging options include -v verbose output, showing request/response headers, --trace or --trace-ascii logging all incoming/outgoing data, and -D <filename> dumping HTTP headers to a file.

How do I download a file if the server uses a self-signed SSL certificate?

You can download files from servers with self-signed or untrusted SSL certificates by using the -k or --insecure option. Be aware that this bypasses SSL certificate verification and should only be used in trusted, controlled environments where the risk is understood.

Can curl download files from a specific range of bytes?

Yes, curl can request specific byte ranges using the -r or --range option.

This is often used for streaming or fetching parts of a file.

Example: curl -r 0-999 -o first_kb.txt https://example.com/large_file.txt.

How do I suppress the progress bar and other curl output during a download?

Yes, you can suppress the progress bar and most informational output by using the -s or --silent option.

This is particularly useful when piping curl‘s output to another command or running it in a script.

What should I do if curl reports “Protocol “https” not supported or disabled in libcurl”?

This error means your curl installation was compiled without HTTPS support.

You would need to install a curl package that includes SSL/TLS support e.g., curl-openssl or curl-gnutls on Linux distributions or compile curl from source with the necessary SSL libraries.