There are times where I run a command that I needed to only need it again at a later time.  Most of the time I document my steps, but there are those time where I just do things in the heat of the moment to get what I need done.  So what can one do?  Well when you’re in your command shell and looking for that command you once knew, all you need to do is simply type:  history

History will return a log of all the commands you have typed.  So when in doubt, look back at your history and bring back those lost memories.  Good luck