curl is a tool to transfer data from or to a server, using one of the supported protocols (HTTP, HTTPS, FTP, FTPS, SCP, SFTP, TFTP, DICT, TELNET, LDAP or FILE). The command is designed to work without user interaction.
curl offers proxy support, user authentication, FTP uploading, HTTP posting, SSL connections, cookies, file transfer resume, Metalink, and many other features.

CURL 7.60.0 released.

Changelog

Changes:

• Add CURLOPT_HAPROXYPROTOCOL, support for the HAProxy PROXY protocol
• Add –haproxy-protocol for the command line tool
• Add CURLOPT_DNS_SHUFFLE_ADDRESSES, shuffle returned IP addresses

Bugfixes:

• FTP: shutdown response buffer overflow CVE-2018-1000300
• RTSP: bad headers buffer over-read CVE-2018-1000301
• FTP: fix typo in recursive callback detection for seeking
• test1208: marked flaky
• HTTP: make header-less responses still count correct body size
• user-agent.d:: mention –proxy-header as well
• http2: fixes typo
• cleanup: misc typos in strings and comments
• rate-limit: use three second window to better handle high speeds
• examples/hiperfifo.c: improved
• pause: when changing pause state, update socket state
• multi: improved pending transfers handling => improved performance
• curl_version_info.3: fix ssl_version description
• add_handle/easy_perform: clear errorbuffer on start if set
• More…

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How to use curl

Basic GET

GET a single resource via its URI

The default operation is a GET:

curl http://api.example.com:8080/statuses/1234

GET multiple resources where IDs are in a range

Use square brackets with a dashed range:

curl http://api.example.com:8080/items/[1230-1234]

GET multiple resources where IDs aren’t in a range

Use curly braces with comma-delimited strings:

curl http://api.example.com:8080/products/{abc,def,ghi}/status

Using HTTP Headers

Accept only the application/json content-type

Use the header option: -H or –header

curl -H ‘Accept: application/json’ http://api.example.com:8080/items/1234

Add multiple headers

Use multiple -H options:

curl -H ‘Accept: application/json’ -H ‘Accept-Encoding: gzip’ http://api.example.com:8080/products/a1b2c3ef/status

Note: the output from this is likely to be unreadable because it’s gzipped!

More likely you’d use this with ETags:

curl -H ‘Accept: application/json’ -H ‘If-None-Match: “1cc044-172-3d9aee80″‘ http://api.example.com:8080/products/a1b2c3ef/status

Show the network and HTTP “conversation”

Use the verbose option: -v or –verbose

curl -v -H http://api.example.com

POST and PUT

POST data to a URI

To send data to the server, you use either POST or PUT, depending on what the API requires. To do a POST, you simply use the -d (–data)  with some content:

curl -d “name=Ted” http://api.example.com:8080/customers

Note that this uses application/x-www-form-urlencoded as the Content-Type, i.e.,as if it was submitted by an HTML Form. You can use multiple -d options, which will be combined, e.g., these two commands produce the same content:

curl -d “first=Ted” -d “last=Young” http://api.example.com:8080/customers
curl -d “first=Ted&last=Young” http://api.example.com:8080/customers

If you want to send JSON, you’ll need to specify the Content-Type explicitly using the -H (header) option:

curl -d ‘{“name”: “Ted”}’ -H ‘Content-Type: application/json’ http://api.example.com:8080/items

PUT data to a URI

If you need to use the PUT method, you’ll need to override the method with the -X (–request) option:

curl -X PUT -d ‘{“name”: “Ted”}’ -H ‘Content-Type: application/json’ http://api.example.com:8080/items/1234

Source: Github