Master curl: Essential Command-Line Tricks for HTTP Requests

curl is a widely used command-line tool for making HTTP requests; its name stands for client URL.

It offers many powerful options that can replace graphical tools like Postman.

This article lists the most important curl command-line options for quick reference.

-A

The -A option sets the User-Agent header. By default curl uses curl/[version]. Example:

$ curl -A 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/76.0.3809.100 Safari/537.36' https://google.com

Use -A '' to remove the User-Agent header, or -H 'User-Agent: php/1.0' to set it directly.

-b

The -b option sends cookies to the server. $ curl -b 'foo=bar' https://google.com Multiple cookies can be sent:

$ curl -b 'foo1=bar;foo2=bar2' https://google.com

Read cookies from a file:

$ curl -b cookies.txt https://www.google.com

-c

The -c option writes received cookies to a file.

$ curl -c cookies.txt https://www.google.com

-d

The -d option sends data in the request body, typically for POST requests.

$ curl -d 'login=emma&password=123' -X POST https://google.com/login

Multiple -d arguments are combined, and -d '@data.txt' reads data from a file.

--data-urlencode

Similar to -d but URL‑encodes the data.

$ curl --data-urlencode 'comment=hello world' https://google.com/login

-e

Sets the Referer header.

$ curl -e 'https://google.com?q=example' https://www.example.com

Equivalent to -H 'Referer: …'.

-F

Uploads files using multipart/form‑data.

$ curl -F '[email protected]' https://google.com/profile

Specify MIME type or filename with ;type=… or ;filename=….

-G

Turns data into a query string for a GET request.

$ curl -G -d 'q=kitties' -d 'count=20' https://google.com/search

-H

Adds arbitrary HTTP headers.

$ curl -H 'Accept-Language: en-US' https://google.com

Multiple headers can be added, and JSON payloads can be sent with -H 'Content-Type: application/json'.

-i

Includes response headers in the output.

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

-I

Sends a HEAD request and shows only the response headers. --head is equivalent.

$ curl -I https://www.example.com

-k

Disables SSL certificate verification.

$ curl -k https://www.example.com

-L

Follows redirects.

$ curl -L -d 'tweet=hi' https://api.twitter.com/tweet

--limit-rate

Limits transfer speed, e.g., --limit-rate 200k caps bandwidth at 200 KB/s.

-o

Saves the response body to a file.

$ curl -o example.html https://www.example.com

-O

Saves to a file using the remote name.

$ curl -O https://www.example.com/foo/bar.html

-s

Silent mode: no progress or error messages.

$ curl -s https://www.example.com

-S

Shows errors only, usually combined with -s.

$ curl -S -s -o /dev/null https://google.com

-u

Provides basic authentication credentials. $ curl -u 'bob:12345' https://google.com/login Credentials can also be embedded in the URL.

-v

Verbose mode prints the full request/response exchange for debugging. $ curl -v https://www.example.com The --trace - option outputs raw binary data as well.

-x

Specifies a proxy, e.g., -x socks5://user:pass@proxy:8080 or an HTTP proxy.

$ curl -x socks5://james:[email protected]:8080 https://www.example.com

-X

Explicitly sets the HTTP method, such as -X POST. $ curl -X POST https://www.example.com Original link: http://www.ruanyifeng.com/blog/2019/09/curl-reference.html