In Linux, Curl command is a tool to transfer data from or to a server. In Linux, curl command is used to test an application's endpoint or connectivity to an upstream service endpoint. It is used to determine if the application can reach another service, like a database, or to check if the service is up and running . This  command doesn’t require any user interaction. Example: $ curl -I -s application:5000
HTTP/1.0 500 INTERNAL SERVER ERROR This example with an exception shows that the application can't reach server. Options used In the above command, -I option -> shows the header information
-s option -> silences the response body. Curl command with -O option is  used to download the file : Usage : curl -O http://knowledgehut.com/myfile.tar.gz #Save the file as tar,gz