curl

Fetch a page, see only the headers with curl -I, save it with curl -o — the quickest way to check a server answers.

>_ Try it: a simulated Linux, right herenothing runs on your computer

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Examples

curl localhost:8080 ask the container on port 8080
curl -I localhost:8080 just the status and headers
curl -s localhost:8080 | grep title only the line you care about
curl -o page.html localhost:8080 save the page into a file
head -n 4 page.html it's in the file
curl -O localhost:8080/index.html save it as index.html, the name in the URL

How it works

curl URL asks a web server for a page and prints what comes back. It is the first thing to try when a site "doesn't work": does anything answer at all?

-I shows only the headers (the status line HTTP/1.1 200 OK says if it worked), -o FILE saves the answer into a file instead of printing it.

Syntax

curl [-I] [-i] [-s] [-o FILE | -O] URL

Options

Option	What it does
`URL`	the address: localhost:8080, http://web-01, https://…
`-I`	only the headers
`-i`	the headers, then the page
`-s`	silent: no progress meter or errors
`-o FILE`	save the answer into FILE
`-O`	save it under the name at the end of the URL

Good to know

"Couldn't connect to server" means nothing listens on that port: is the container running, and did you publish the port with -p?
This playground is offline: curl reaches your own containers and servers, not the internet.