As far as I know this application doesn't exist yet. What I think it should be is a windows where I can choose a terminal command such as dd and then it will use the man page for the command to help me with the arguments and output an expected result of the command.
For instance the man page for dd is online here. It is pretty crap actually, this is a command I use fairly often in the form,
dd if=<path to input file> of=<path to output file>
In English this would read, use the dd program to write the place specified in if= to the place specified in of=.
If you look at the man page though all you get is dd [OPERAND]… and dd OPTION. With a long list of options afterwards and no real idea what happens when you use some of them.
What would be far nicer is to be able to choose the dd command, have the if and of pop up as drop down menu options if needed and with a decent explanation of what is going on underneath.
Actually, come to think of it the dd command was probably a bad choice. What about the confusion that can happen when using a wild card at the end of a path, or trying to make sure you are actually moving all the files in one directory to another without them all disappearing because you made a mistake in the path.
It would be a lot nicer learning the command line on Linux if we could simulate what we are telling the operating system.