Curl Cheatsheet

curl is used in the command line or in scripts to transfer data. It is also used nearly everywhere: in cars, television sets, routers, printers, audio equipment, mobile phones, tablets, settop boxes, media players and is the internet transfer backbone for thousands of software applications affecting billions of humans daily.

A little history: The name stands for "Client URL", which was first released in 1997. The original author and lead developer is the Swedish developer Daniel Stenberg, who created cURL because he wanted to automate the fetching of currency exchange rates for IRC users.

Download a single file

curl http://path.to.the/file

Download a file and specify a new filename

curl http://example.com/file.zip -o new_file.zip

Download multiple files

curl -O URLOfFirstFile -O URLOfSecondFile

Download all sequentially numbered files (1-24)

curl http://example.com/pic[1-24].jpg

Download a file and pass HTTP Authentication

curl -u username:password URL

Download a file with a Proxy

curl -x proxysever.server.com:PORT http://addressiwantto.access

Download a file from FTP

curl -u username:password -O ftp://example.com/pub/file.zip

Get an FTP directory listing

curl ftp://username:password@example.com

Resume a previously failed download

curl -C - -o partial_file.zip http://example.com/file.zip

Fetch only the HTTP headers from a response

curl -I http://example.com

Fetch your external IP and network info as JSON

curl http://ifconfig.me/all/json

Limit the rate of a download

curl --limit-rate 1000B -O http://path.to.the/file

Get your global IP

curl httpbin.org/ip

Get only the HTTP status code

curl -o /dev/null -w '%{http_code}\n' -s -I URL

Common Options

-#, --progress-bar Make curl display a simple progress bar instead of the more informational standard meter.

-b, --cookie <name=data> Supply cookie with request. If no =, then specifies the cookie file to use (see -c).

-c, --cookie-jar <file name> File to save response cookies to.

-d, --data <data> Send specified data in POST request. Details provided below.

-f, --fail Fail silently (don't output HTML error form if returned).

-F, --form <name=content> Submit form data.

-H, --header <header> Headers to supply with request.

-i, --include Include HTTP headers in the output.

-I, --head Fetch headers only.

-k, --insecure Allow insecure connections to succeed.

-L, --location Follow redirects.

-o, --output <file> Write output to . Can use --create-dirs in conjunction with this to create any directories specified in the -o path.

-O, --remote-name Write output to file named like the remote file (only writes to current directory).

-s, --silent Silent (quiet) mode. Use with -S to force it to show errors.

-v, --verbose Provide more information (useful for debugging).

-w, --write-out <format> Make curl display information on stdout after a completed transfer. See man page for more details on available variables. Convenient way to force curl to append a newline to output: -w "\n" (can add to ~/.curlrc).

-X, --request The request method to use.

POST

When sending data via a POST or PUT request, two common formats (specified via the Content-Type header) are:

• application/json
• application/x-www-form-urlencoded

Many APIs will accept both formats, so if you're using curl at the command line, it can be a bit easier to use the form urlencoded format instead of json because

• the json format requires a bunch of extra quoting
• curl will send form urlencoded by default, so for json the Content-Type header must be explicitly set

This gist provides examples for using both formats, including how to use sample data files in either format with your curl requests.

curl usage

For sending data with POST and PUT requests, these are common curl options:

• request type

  • -X POST
  • -X PUT

• content type header

• -H "Content-Type: application/x-www-form-urlencoded"

• -H "Content-Type: application/json"

• data

  • form urlencoded: -d "param1=value1&param2=value2" or -d @data.txt
  • json: -d '{"key1":"value1", "key2":"value2"}' or -d @data.json

Examples

POST application/x-www-form-urlencoded

application/x-www-form-urlencoded is the default:

curl -d "param1=value1&param2=value2" -X POST http://localhost:3000/data

explicit:

curl -d "param1=value1&param2=value2" -H "Content-Type: application/x-www-form-urlencoded" -X POST http://localhost:3000/data

with a data file

curl -d "@data.txt" -X POST http://localhost:3000/data

POST application/json

curl -d '{"key1":"value1", "key2":"value2"}' -H "Content-Type: application/json" -X POST http://localhost:3000/data

with a data file

curl -d "@data.json" -X POST http://localhost:3000/data