The program 'rails' is currently not installed. You can install it by typing: sudo apt-get install rails

user@localhost:~$ rails new blog
The program 'rails' is currently not installed.  You can install it by typing: sudo apt-get install rails

If you get this message when you were creating new rails project. To fix this issue

1. Go to profile settings (.bashrc or .bash_profile)

2. Add this line at end of the file

[[ -s "$HOME/.rvm/scripts/rvm" ]] && source "$HOME/.rvm/scripts/rvm" # Loading RVM into a shell

3. If you are in existing shell prompt, execute this command

source ~/.bashrc
or
source ~/.bash_profile

If you open a new terminal, you can notice  that rails command is automatically available.I hope this post helpful to fix rails command issue.



Note:
I believe you have installed ruby by Ruby Version Manger(RVM). Refer the installation steps
https://rvm.io/rvm/install/