Error message about "cURL PHP extension" when trying to run Arc

Just to clarify, you hand installed PHP but used apt-get to install php5-curl?

php -i will show you details about the actual PHP you're running, including if curl is actually installed.

Yes, that is correct. I did php -i, searched for "curl" and came up with nothing. I'll try rebuilding my PHP using --with-curl and see if that results in anything better. I'll follow the instructions at http://php.net/manual/en/curl.installation.php and get back to you with my results.

You may just want Ubuntu's PHP instead of building it by hand (you may also run into other problems by hand). sudo apt-get install php5 php5-curl

I can give that a shot. Manually building PHP with --with-curl=/usr/bin also worked for me. Thanks for your help, Chad!