I found I couldn't enter my password in unusual situations, e.g. holding the keyboard in one hand, typing with the other. I finally cottoned on that my fingers'

I found I couldn't enter my password in unusual situations, e.g. holding the keyboard in one hand, typing with the other. I finally cottoned on that my fingers' muscle memory was typing the password consistently but it wasn't what I thought it was; it had been corrupted by similar N-grams in Unix commands from the moment I'd first entered it twice to passwd(1).