Curl is a very useful tool. A lot of times in troubleshooting, you will be trying to solve an issue with very little information. Let us say, hypothetically, that someone had an issue with their site,
Magic PHP Getting
You can use this site here:
Or even easier maybe.
curl -I "the URL of the site in question, no quotes"
curl -I https://ganstapenguin.com/blog/index.php HTTP/1.1 301 Moved Permanently Date: Mon, 08 Apr 2019 10:43:05 GMT Server: Apache/2.4.37 () OpenSSL/1.0.2k-fips X-Powered-By: PHP/7.2.14 X-Redirect-By: WordPress Upgrade: h2,h2c Connection: Upgrade Location: https://ganstapenguin.com/blog/ Content-Type: text/html; charset=UTF-8
The first line is my Command line input, the 5th line down is the PHP version this server is running.
Here is another session of troubleshooting a different WordPress problem on their support forums,