Getting the following error when trying to use phantomjs from ruby on Ubuntu:
 Failure/Error: visit root_path
 Cliver::Dependency::NotFound:
   Could not fin         
        
Other possible solution is to add executable rights to file:
# download phantomjs
$ curl --output /home/user/.rvm/bin/phantomjs https://s3.amazonaws.com/circle-downloads/phantomjs-2.1.1
# set rights 
$ chmod +x /home/user/.rvm/bin/phantomjs
# check
$ which phantomjs
/home/user/.rvm/bin/phantomjs
And also it is not recommended by poltergeist to use phantomjs from official Ubuntu repos:
DO NOT use phantomjs from the official Ubuntu repositories, since it doesn't work well with poltergeist.