Status and Timing

-w prints facts about the transfer after it finishes, using placeholders in a format string:

curl -s -o /dev/null -w '%{http_code} %{size_download}\n' URL

The ones worth knowing:

• %{http_code}: the status code
• %{size_download}: bytes received
• %{time_total}: how long the whole thing took
• %{url_effective}: the URL finally used, after any redirects

This is what makes curl scriptable. Instead of eyeballing a page you get a number a script can test, which is how uptime checks and deployment smoke tests are usually built.

Pair it with -o /dev/null so the body does not get in the way, and remember the \n, or your output runs into the next line.