Linux curl command

The Linux curl command is a powerful tool used to transfer data to or from a server. It supports various protocols like HTTP, HTTPS, FTP, and more. With its versatile options, you can customize the request headers, follow redirects, save the output to a file, and even send data in different formats. In addition to making basic GET and POST requests, curl can also perform tasks like downloading files, testing APIs, and automating tasks through scripts. Mastering the curl command is essential for any developer or system administrator working in a Linux environment.

curl Syntax:

curl [options] [URL]

Options:

Option	Description
-X, —request	Specify the request method (GET, POST, etc.)
-H, —header	Add a header to the request
-d, —data	Send data in the request body
-o, —output	Write output to a file
-v, —verbose	Make the operation more talkative
-i, —include	Include the HTTP-header in the output
-A, —user-agent	Specify the User-Agent string

Parameters:

Parameter	Description
URL	The URL to send the request to
data	Data to be sent in the request body
method	The request method to use (GET, POST, PUT, etc.)
file	File to write output to
header	Custom header to be included in the request

Caution

Exercise caution when using the curl command, especially with options like -d (data) as it could potentially send sensitive information in the request body. Always ensure that the URL and data being sent are secure and intended recipients of the request.

curl Usage:

Download a File from a URL

curl -O https://www.example.com/file.zip

Downloads a file named “file.zip” from the specified URL.

Follow Redirects

curl -L https://www.example.com

Retrieves a page content from a URL and follows any redirects to the final destination.

Save Output to a File

curl -o output.txt https://www.example.com/data

Retrieves data from a URL and saves the output to a file named “output.txt”.

Include HTTP Headers in Output

curl -i https://www.example.com/api

Retrieves the HTTP headers along with the content from the specified URL.

Tip

When using the curl command in Linux, remember to check for available options and flags in the curl manual (man curl) for detailed usage instructions and examples.

How do I interact with a website using curl in Linux?

To interact with a website using curl in Linux, you can send a GET request to the URL. For example:

curl https://www.example.com

How do I download a file using curl in Linux?

To download a file using curl in Linux, specify the URL of the file with the -o option to save it with a specific name. For example:

curl -o filename.zip https://www.example.com/file.zip

How do I follow redirects with curl in Linux?

To follow redirects during a curl request in Linux, use the -L or --location option. For example:

curl -L https://www.example.com

How do I set a custom user agent with curl in Linux?

To set a custom user agent header in the request using curl in Linux, use the -A or --user-agent option. For example:

curl -A "Custom User Agent" https://www.example.com

How do I send POST data with curl in Linux?

To send POST data using curl in Linux, use the -d or --data option followed by the data to be sent. For example:

curl -d "key1=value1&key2=value2" https://www.example.com/api

How do I download a file with progress information using curl in Linux?

To download a file with progress information displayed in Linux, use the -# or --progress-bar option with curl. For example:

curl -# -o filename.zip https://www.example.com/file.zip

Applications of the curl command

• Download files from the web
• Upload files to a server
• Test API endpoints
• Retrieve web pages or website content
• Follow redirects
• Send form data
• Perform RESTful operations
• Transfer data over different protocols like HTTP, HTTPS, FTP, etc.