Linux Network Tools - cURL

2017-06-13
tutorial linuxnetworking

cURL (see URL)

curl is a command line tool that uses libcurl to make URL requests. libcurl is a portable library that works across many platforms. It supports cookies, FTP, HTTP, HTTPS, proxy tunneling, etc.

Quick Reference

$ curl -i -X GET http://localhost:7000/users

$ curl -i -H "Content-Type: application/json" -d '{"username":"user","password":"password"}' -X POST http://localhost:7000/api/login

$ curl -i -d '{"username":"user","password":"password"}' -X POST http://localhost:7000/users

$ curl -i -d '{"username":"user","password":"password"}' -X PUT http://localhost:7000/users/1

$ curl -X DELETE http://localhost/users/1

Flags

  • -#, --progress-bar: display a simple progress bar.

  • -b, --cookie <file-or-pairs>: curl -b "X=1; Y=Yes" http://localhost:7000/users.

  • -d, --data <data>: request body.

  • -F, --form <name=content>: form data curl -F "user=james;type=text/foo" http://localhost:7000/users.

  • -g, --globoff: can include the {}[] characters in the URL.

  • -H, --header <header>: headers included with the request.

  • -i, --include: include HTTP headers in the output.

  • -I, --head: fetch headers only

  • -L, --location: if a header and 3XX response code is received, repeat the query to the new location.

  • -v, --verbose: provide more information.

  • -X, --request: DELETE, GET, HEAD, OPTIONS, POST, PUT. If not included will default to GET.

Examples

GET

We can make a simple GET request by typing the address and port after curl. curl assumes the request is GET if no explicit request type is given.

$ curl localhost:7000

We can test it out by listening to port 7000 with nc, then make a connection with curl and type something in the command line window where nc is running.

$ nc -l 7000
GET / HTTP/1.1
Host: localhost:7000
User-Agent: curl/7.47.0
Accept: */*

Hello cURL!
$ curl localhost:7000
Hello cURL!

POST

Login request with JSON.

$ curl -H "Content-Type:application/json"  -d '{"email":"user@home.com",password:"password"}"' -X POST http://localhost:3000/api/login

Make authenticated request.

$ curl -H "X-Auth-Token: 123abc" -H "X-User-Id: 112233" -H "Content-Type:application/json"  -d '{"email":"newuser@home.com",password:"password"}"' -X POST http://localhost:3000/api/users

Login request for a GraphQL API.

$ curl -H "Content-Type:application/json"  -d '{"query":"mutation{login(email:"user@home.com",password:"password"){token,user}}"' -X POST http://localhost:3000/graphql

References