Rails: The program 'rails' is currently not installed on Ubuntu 16.04 - ruby-on-rails

Question

I installed rvm ruby and gem.
When I used gem to install rails, it's like this:
woyuxuxu123#ubuntu:~$ sudo gem install rails
[sudo] password for woyuxuxu123:
Successfully installed rails-5.1.4
Parsing documentation for rails-5.1.4
Done installing documentation for rails after 0 seconds
1 gem installed
But when I enter rails -v, I got:
woyuxuxu123#ubuntu:~$ rails -v
The program 'rails' is currently not installed. You can install it by typing:
sudo apt install ruby-railties
I tried some solutions, but did not work for me, such as
source ~/.rvm/scripts/rvm
Someone mentioned the path. Here is how it looks
RubyGems Environment:
EXECUTABLE DIRECTORY: /usr/local/bin
woyuxuxu123#ubuntu:~$ echo $PATH
/home/woyuxuxu123/bin:/home/woyuxuxu123/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/woyuxuxu123/.rvm/bin:/home/woyuxuxu123/.rvm/bin
What should I do?

Answer 1

I faced a similar issue for Rails 5.2 and Ubuntu 18.04. I had an already setup server with Ruby and Rails installed, but I couldn't access them.
The error output was:
The program 'rails' is currently not installed. You can install it by typing:
sudo apt install ruby-railties
The issue is simply caused by the rails executable not being globally accessible by programs.
Here's how I solved it
Note: If you are working on a production server, endeavour to make a backup of your database before trying out the solution below to avoid data loss.
For my case, my version manager was rbenv and not rvm
Re-install rbenv itself. Clone the rbenv repository from GitHub into the directory ~/.rbenv:
git clone https://github.com/rbenv/rbenv.git ~/.rbenv
Next, add ~/.rbenv/bin to your $PATH so that you can use the rbenv command line utility. Do this by altering your ~/.bashrc file so that it affects future login sessions:
echo 'export PATH="$HOME/.rbenv/bin:$PATH"' >> ~/.bashrc
Then add the command eval "$(rbenv init -)" to your ~/.bashrc file so rbenv loads automatically:
echo 'eval "$(rbenv init -)"' >> ~/.bashrc
Next, apply the changes you made to your ~/.bashrc file to your current shell session:
source ~/.bashrc
Verify that rbenv is set up properly by using the type command, which will display more information about the rbenv command:
type rbenv
Your terminal window will display the following:
rbenv is a function
rbenv ()
{
local command;
command="${1:-}";
if [ "$#" -gt 0 ]; then
shift;
fi;
case "$command" in
rehash | shell)
eval "$(rbenv "sh-$command" "$#")"
;;
*)
command rbenv "$command" "$#"
;;
esac
}
If everything worked right, running the command below will display the versions of Ruby and Rails previously installed on your machine:
ruby -v
rails -v
Else, run a fresh installation of Ruby and Rails on your machine.
That's all
I hope this helps

Answer 2

Probably you forgot to add rvm script to your .bash_profile:
[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm"
Try running rvm repair all and then restart your terminal.