Mastering curl: Essential Command‑Line Options for HTTP Requests

简介

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

It offers powerful functionality with dozens of options, and when mastered it can replace graphical tools like Postman.

This article lists the most common curl options as a quick reference, based on the "curl cookbook". Example outputs are omitted for brevity.

Without any arguments, curl performs a GET request.

$ curl https://www.example.com

-A

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

$ 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 an empty string to remove the User‑Agent header: $ curl -A '' https://google.com You can also set the header directly with -H:

$ curl -H 'User-Agent: php/1.0' https://google.com

-b

The -b option sends cookies to the server.

$ curl -b 'foo=bar' https://google.com

$ 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, automatically switching to POST and adding the Content-Type: application/x-www-form-urlencoded header.

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

You can read data from a file using @:

$ curl -d '@data.txt' https://google.com/login

--data-urlencode

This option works like -d but URL‑encodes the data automatically.

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

-e

Set the HTTP Referer header.

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

Or use -H directly:

curl -H 'Referer: https://google.com?q=example' https://www.example.com

-F

The -F option uploads files as multipart/form‑data.

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

Specify MIME type or filename:

$ curl -F '[email protected];type=image/png' https://google.com/profile
$ curl -F '[email protected];filename=me.png' https://google.com/profile

-G

Use -G to send data as a query string in a GET request.

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

Combine with --data-urlencode for URL‑encoded parameters.

$ curl -G --data-urlencode 'comment=hello world' https://www.example.com

-H

Add arbitrary HTTP headers.

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

Send JSON data with a custom Content-Type header:

$ curl -d '{"login": "emma", "pass": "123"}' -H 'Content-Type: application/json' https://google.com/login

-i

Print response headers followed by the body.

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

-I

Send a HEAD request and display only the response headers.

$ curl -I https://www.example.com
# equivalent to --head
$ curl --head https://www.example.com

-k

Skip SSL certificate verification.

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

-L

Follow HTTP redirects.

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

--limit-rate

Throttle bandwidth to simulate slow connections.

$ curl --limit-rate 200k https://google.com

-o

Save the response body to a file (similar to wget).

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

-O

Save the response using the remote filename.

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

-s

Silent mode: suppress progress and error messages. $ curl -s https://www.example.com Combine with -o /dev/null to discard all output unless an error occurs:

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

-S

Show errors only, typically used with -s.

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

-u

Provide username and password for HTTP authentication. $ curl -u 'bob:12345' https://google.com/login Credentials can also be embedded in the URL:

$ curl https://bob:[email protected]/login

-v

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

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

-x

Specify a proxy for the request.

$ curl -x socks5://james:[email protected]:8080 https://www.example.com
# default protocol is HTTP if omitted
$ curl -x james:[email protected]:8080 https://www.example.com

-X

Explicitly set the HTTP method.

$ curl -X POST https://www.example.com