Curl is a multipurpose tool for interacting with various internet protocols by URI. 

~ $ curl -v https://edoceo.com/

Posting Data with Curl

curl --data 'foo=bar' \
	--trace-ascii /dev/stdout \
	https://edoceo.com/

Posting JSON Data with Curl

curl --data '{"id":"value", ""}' http://

This second example show how to POST message to HipChat from the command line. You must use your own authentication and room values. 

auth=""
room="edoceo"

curl \
	--header "Authorization: Bearer $auth" \
	--header "Content-Type: application/json" \
	--request 'POST' \
	--data @- \
	https://api.hipchat.com/v2/room/$room/notification <<EOP
{
	"color":"red",
	"notify":false,
	"message":"Some Message Text Here, Careful of Quotes",
	"message_format":"text"
}
EOP

Inspect SSL Certificates

Using curl we can also view information about the SSL certificates from the server. This also helps to diagnose if there are issues with the certificate chain. 

~ $ curl -v https://edoceo.com/

Post STDOUT to Server via curl

Here we take the output of lshw and send that up to the Linux Hardware Database.

~ $ lshw -json |  curl -d@- -qs "http://edoceo-demo.com/upload"
~ $ lshw -json |  curl --data-ascii @- -qs "http://edoceo-demo.com/upload"
~ $ lshw -json |  curl --data-binary @- -qs "http://edoceo-demo.com/upload"

Tracing

Use the --trace-ascii option. 

curl http://edoceo.com/ -d "hello=there" --trace-ascii /dev/stdout
Enables a full trace dump of all incoming and outgoing data, including descriptive informa‐ tion, to the given output file. Use "-" as filename to have the output sent to stdout.
This is very similar to --trace, but leaves out the hex part and only shows the ASCII part of the dump. It makes smaller output that might be easier to read for untrained humans.
This option overrides previous uses of -v, --verbose or --trace.
If this option is used several times, the last one will be used. 
== Info: Adding handle: conn: 0x14a8880
== Info: Adding handle: send: 0
== Info: Adding handle: recv: 0
== Info: Curl_addHandleToPipeline: length: 1
== Info: - Conn 0 (0x14a8880) send_pipe: 1, recv_pipe: 0
== Info: About to connect() to edoceo.com port 80 (#0)
== Info:   Trying 74.207.248.164...
== Info: Connected to edoceo.com (74.207.248.164) port 80 (#0)
=> Send header, 74 bytes (0x4a)
0000: GET / HTTP/1.1
0010: User-Agent: curl/7.33.0
0029: Host: edoceo.com
003b: Accept: */*
0048: 
<= Recv header, 17 bytes (0x11)
0000: HTTP/1.1 200 OK
<= Recv header, 37 bytes (0x25)
0000: Date: Thu, 09 Jan 2014 02:05:51 GMT
== Info: Server Apache is not blacklisted
<= Recv header, 16 bytes (0x10)
0000: Server: Apache
<= Recv header, 55 bytes (0x37)
0000: Set-Cookie: edoceo=edla1uattv6kbep8ofqp3q5ri6; path=/
<= Recv header, 40 bytes (0x28)
0000: Expires: Thu, 19 Nov 1981 08:52:00 GMT
<= Recv header, 79 bytes (0x4f)
0000: Cache-Control: must-revalidate, no-cache, no-store, post-check=0
0040: , pre-check=0
<= Recv header, 22 bytes (0x16)
0000: Content-Language: en
<= Recv header, 23 bytes (0x17)
0000: Vary: Accept-Encoding
<= Recv header, 28 bytes (0x1c)
0000: Transfer-Encoding: chunked
<= Recv header, 40 bytes (0x28)
0000: Content-Type: text/html; charset=utf-8
<= Recv header, 2 bytes (0x2)
0000: 
<= Recv data, 1089 bytes (0x441)

See Also