Linux Commands and Scripts

Tips On How to Use ‘Curl’ Command in Linux

In this article, we have explained tips on how to use Curl command in Linux.

The curl command transfers data to or from a network server, using one of the supported protocols. Since cURL uses libcurl, it supports a range of common network protocols, currently including HTTP,[10][14] HTTPS, SOAP requests.

Let’s get started and learn curl commands.

1. View curl Version

The -V or –version options will not only return the version, but also the supported protocols and features in your current version.

$ curl –version

curl 7.47.0 (x86_64-pc-linux-gnu) libcurl/7.47.0 GnuTLS/3.4.10 zlib/1.2.8 libidn/1.32 librtmp/2.3

Protocols: dict file ftp ftps gopher http https imap imaps ldap ldaps pop3 pop3s rtmp rtsp smb smbs smtp smtps telnet tftp

Features: AsynchDNS IDN IPv6 Largefile GSS-API Kerberos SPNEGO NTLM NTLM_WB SSL libz TLS-SRP UnixSockets

2. Download a File

If you want to download a file, you can use curl with the -O or -o options. The former will save the file in the current working directory with the same name as in the remote location, whereas the latter allows you to specify a different filename and/or location.

$ curl -O # Save as yourfile.tar.gz
$ curl -o newfile.tar.gz # Save as newfile.tar.gz

3. Resume an Interrupted Download

If a download was interrupted for some reason (for example, using Ctrl + c), you can resume it very easily. The use of -C – (dash C, space dash) tells curl to resume the download beginning where it left off.

$ curl -C – -O

4. Download Multiple Files

With the following command, you will download info.html and about.html from and, respectively, in one go.

$ curl -O -O

5. Download URLs From a File

If you combine curl with xargs, you can download files from a list of URLs in a file.

# xargs -n 1 curl -O < listurls.txt

6. Use a Proxy with or without Authentication

If you are behind a proxy server listening on port 8080 at, do.

# curl -x -U user:password -O

where you can skip -U user:password if your proxy does not require authentication.

7. Query HTTP Headers

HTTP headers allow the remote web server to send additional information about itself along with the actual request. This provides the client with details on how the request is being handled.

To query the HTTP headers from a website, do:

# curl -I

8. Make a POST request with Parameters

The following command will send the firstName and lastName parameters, along with their corresponding values, to

# curl –data “firstName=John&lastName=Doe”

You can use this tip to simulate the behaviour of a regular HTML form.

9. Download Files from an FTP Server with or without Authentication

If a remote FTP server is expecting connections at ftp://yourftpserver, the following command will download yourfile.tar.gz in the current working directory.

# curl -u username:password -O ftp://yourftpserver/yourfile.tar.gz

where you can skip -u username:password if the FTP server allows anonymous logins.

10. Upload Files to an FTP server with or without Authentication

To upload a local file named mylocalfile.tar.gz to ftp://yourftpserver using curl, do:

# curl -u username:password -T mylocalfile.tar.gz ftp://yourftpserver

11. Specify User Agent

The user agent is part of the information that is sent along with an HTTP request. This indicates which browser the client used to make the request. Let’s see what our current curl version uses as default, and let’s change it later to “I am a new web browser”:

# curl -I http://localhost –user-agent “I am a new web browser”

12. Store Website Cookies

Want to see which cookies are downloaded to your computer when you browse to Use the following command to save them to cnncookies.txt. You can then use cat command to view the file.

# curl –cookie-jar cnncookies.txt -O

13. Send Website Cookies

You can use the cookies retrieved in the last tip in subsequent requests to the same site.

# curl –cookie cnncookies.txt

14. Modify Name Resolution

If you’re a web developer and want to test a local version of before pushing it live, you can make curl resolve to your localhost like so:

# curl –resolve

Thus, the query to will tell curl to request the site from localhost instead of using DNS or the /etc/hosts file.

15. Limit Download Rate

To prevent curl from hosing your bandwidth, you can limit the download rate to 100 KB/s as follows.

# curl –limit-rate 100K -O

Today, we have learned what is Curl and how to use Curl command in Linux.

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