I installed curl this command (i use Ubuntu):
sudo apt-get install curl
When I test simple program using g++ test.cpp
g++ test.cpp
If after the installation curl-dev luarocks does not see the headers:
find /usr -name 'curl.h' Example: /usr/include/x86_64-linux-gnu/curl/curl.h luarocks install lua-cURL CURL_INCDIR=/usr/include/x86_64-linux-gnu/