I was following the instructions on https://secure.phabricator.com/book/phabricator/article/arcanist/. However, every time I try to run ```arc```, I get the following error message:
```
PHP CONFIGURATION ERRORS
You need to install the cURL PHP extension, maybe with 'apt-get install php5-curl' or 'yum install php53-curl' or something similar.
```
This error message persists even after I sudo apt-get install php5-curl (I'm on an Ubuntu). I installed PHP from the .tar.bz2 link for this from http://us3.php.net/downloads.php just yesterday.
Any ideas?