getting unexpected shell command behaviour after installing pry-rails.

[codemilan]

I installed pry-rails gem (0.3.4) in rails 4.1.0 and ruby 2.1.3 app. when i switch to rails console the pry works fine in rails console but when i exit rails console with pry, then the console commands behave like below:-

1. when hit 'cd' it enters pry console.
2. when hit 'cd ..' no-command found error.
3. when hit 'clear' lists the directory in current folder.
   I don't know why this sort of behaviour. Is this issue with gem or some kind of malware in my Ubuntu pc.
   This behaviour is only seen in rails app directory(in which pry-rails is installed), if i move to other directory with command cd ../another-dir (which works) the terminal command works.