15+ curl command examples in Linux [Cheat Sheet] | GoLinuxCloud (2024)

Introduction to curl command

curl is a popular command that helps to transfer data from or to a remote server. It supports many protocols including HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, DICT, TELNET, LDAP, and FILE.

curl offers useful features like file transfer resume, proxy support, FTP upload, user authentication, POST method, bandwidth limit, and many more. curl is powered by libcurl library for all transfer-related features.

How to install curl

curl is already available in newer versions of Linux distributions. In case, if you get curl command not found, you can easily install it using the system's package manager tool.

Install curl on CentOS, RHEL, Fedora

$ sudo dnf install curl

Install curl on Ubuntu and Debian

$ sudo apt install curl

Syntax to use curl command

The basic syntax for curl command is:

$ curl [option] url

Different examples to use curl command

1. Show content of the URL

When the URL is specified to the curl command, it displays the source code (HTML content) of that URL.

$ curl https://linux.die.net

Sample Output:

2. Retrieve only HTTP headers of the URL

The -I or --head option tells curl to fetch the HTTP headers only.

$ curl -I https://linux.die.net

OR

$ curl --head https://linux.die.net

Sample Output:

3. Download and save the content to file

The output of the curl command can be saved using the -o or --output option. This option also requires the file name parameter.

$ curl -o filename linux.die.net

OR

$ curl --output filename linux.die.net

Sample Output:

The following example saves the source code of https://linux.die.net in a docpage.html file.

curl displays the progress meter which shows transfer speed, file size, time elapsed, etc.

4. Download a file with curl

If the URL represents a file, you can download and save it as a new name using the -o or --output option.

In this example, the filename on the website is ping-website.png which we will save as ping.png in our system.

$ curl -o ping.png https://www.golinuxcloud.com/wp-content/uploads/ping-website.png

OR

$ curl --output ping.png https://www.golinuxcloud.com/wp-content/uploads/ping-website.png

Sample Output:

5. Download a file with the same name

If you want to save the file with the original name used on the website, you can use the -O or --remote-name option.

$ curl -O https://www.golinuxcloud.com/wp-content/uploads/ping-website.png

OR

$ curl --remote-name https://www.golinuxcloud.com/wp-content/uploads/ping-website.png

Sample Output:

6. Download multiple files

You can specify -o or -O option as many times as the number of URLs you have. This helps you to download multiple files with the same command.

$ curl -O url1 -O url2

Sample Output:

The following example downloads both image files ping-count.png and ping-localhost with the same name in the current directory.

golinux@ubuntu-PC:~$ curl -O https://www.golinuxcloud.com/wp-content/uploads/ping-count.png -O https://www.golinuxcloud.com/wp-content/uploads/ping-localhost.png % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed100 18338 100 18338 0 0 33524 0 --:--:-- --:--:-- --:--:-- 33524 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed100 17018 100 17018 0 0 180k 0 --:--:-- --:--:-- --:--:-- 180k

7. Resume the download

If a download is interrupted or stopped, it can be resumed using the -C or --continue-at option. When curl is used with -C - option, it automatically finds out where to resume the transfer.

$ curl -C - -O https://releases.ubuntu.com/22.04.1/ubuntu-22.04.1-desktop-amd64.iso

OR

$ curl --continue-at - -O https://releases.ubuntu.com/22.04.1/ubuntu-22.04.1-desktop-amd64.iso

Sample Output:

Here, we are resuming the download of Ubuntu 22.04 iso file.

8. Follow redirects with curl

By default, curl does not follow the redirects. If the requested page is moved to a different location, we can use curl with -L or --location option to make curl follow a redirect.

$ curl -L linux.die.net

OR

$ curl --location linux.die.net

Sample Output:

9. Run curl in silent mode

The -s or --silent option tells curl to hide the progress meter or error messages.

$ curl -s linux.die.net

OR

$ curl --silent linux.die.net

Sample Output:

10. curl command to check HTTP Status

You can use this curl command to check any URL connectivity. If it returns HTTP/2 200, it means the request has succeeded.

$ curl -IsL https://linux.die.net | grep HTTP

Sample Output:

golinux@ubuntu-PC:~$ curl -IsL https://linux.die.net | grep HTTPHTTP/2 200

11. Set the maximum transfer rate

The --limit-rate option lets you specify the maximum transfer rate. The given value will be taken as bytes/second if a suffix is not used.

You can use kilobytes with k suffix, megabytes with m suffix, and gigabytes with g suffix.

The following command downloads the Ubuntu 22.04 iso file with a limited speed of 2 MB.

$ curl --limit-rate 2m -O https://releases.ubuntu.com/22.04.1/ubuntu-22.04.1-desktop-amd64.iso

Sample Output:

This is helpful if you want to limit the speed and not use the entire bandwidth.

12. Download files from authenticated FTP servers

The -u or --user option allows you to specify the username and password to use for server authentication. You can use this syntax to download a file from the password-protected FTP server.

$ curl -u FTP_USERNAME:FTP_PASSWORD ftp://ftp.example.com/file.txt

OR

$ curl --user FTP_USERNAME:FTP_PASSWORD ftp://ftp.example.com/file.txt

13. Upload files to FTP servers

You can use the -T or --upload-file option to upload a file to the FTP server. This option requires you to specify the local file you want to upload.

$ curl -T filename -u FTP_USERNAME:FTP_PASSWORD ftp://ftp.example.com/file.txt

OR

$ curl --upload-file filename -u FTP_USERNAME:FTP_PASSWORD ftp://ftp.example.com/file.txt

14. Send POST requests with curl

Using the -d or --data option, you can send data in a POST request to the specified website. The data must be specified in the field=value pair. You can send multiple data by separating them with a & character.

This command makes a POST request to https://www.example.com/post that has fname and lname fields in the form.

$ curl -d "fname=John&lname=Doe" https://www.example.com/post

OR

$ curl --data "fname=John&lname=Doe" https://www.example.com/post

15. Use a specific proxy

The -x or --proxy option allows you to use a specified HTTP proxy. If you do not specify the port, port number 1080 will be used.

$ curl -x proxy_host:port url

OR

$ curl --proxy proxy_host:port url

16. Specify username and password for proxy authentication

If the proxy server is secured, you can use the -U or --proxy-user option to pass the user name and password value as shown below.

$ curl -U username:password -x proxy_host:port url

OR

$ curl --proxy-user username:password -x proxy_host:port url

17. Using curl with DICT protocol

curl supports DICT, a dictionary network protocol. It is helpful for finding the meaning or definition of the word.

For instance, to view the meaning of word machine, you can use this curl command.

$ curl dict://dict.org/d:machine

Sample Output:

Conclusion

In this tutorial, we have discussed the most common examples of curl commands in Linux. curl is a powerful tool that has a wide range of options. It can come in handy when downloading files and troubleshooting connectivity issues from the command line.

If you have any confusion regarding any examples, please let us know in the comment section.

What's Next

Perform a POST Request Using Curl [Practical Examples]
15+ hping3 command examples in Linux [Cheat Sheet]

Further Reading

man page for curl command