Curl

Return status code only

curl -s -o /dev/null -w "%{http_code}" google.com

curl -s -o /dev/null -i -w "%{http_code}" google.com

curl -s -o /dev/null -I -w "%{http_code}" google.com

curl -s -o /dev/null -I -w "%{http_code}\n" google.com

ref:

Return fail status code

curl --fail http://some-url.com
echo $?

-f, --fail (HTTP) Fail silently (no output at all) on server errors