You can get around the in-under-attack-mode by selecting 'Copy as cUrl' in the network section under developer tools of any major browser.
This copies all the required cookies so your curl can be 'authenticated'. How long these cookies last i would assume would be up to cloudflare.
SideNote: The curl must be run on the same IP as you were loading the site with.
Also for any real test/developing environment I would suggest selenium and/or phantomjs which are alot better and easily scriptable languages for website testing.
curl 'https://ilikeurls.net/ourpage.php?do=command' \
-H 'Host: ilikeurls.net' \
-H 'User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:33.0) Gecko/20100101 Firefox/33.0' \
-H 'Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8' \
-H 'Accept-Language: en-US,en;q=0.5' \
-H 'Referer: https://ilikeurls.net/outpage.php' \
-H 'Cookie: all required cookies will appear here' \
-H 'Connection: keep-alive'\
--compressed
Though you might be better off using selenium or phantomjs to script out these tests.