Running the notebook
If you have Jupyter installed, you can create a notebook and switch to IRkernel from the dropdown menu:

You can also start other intefaces with an R kernel:
# “ir” is the kernel name installed by the above IRkernel::installspec()
jupyter qtconsole --kernel=ir
jupyter console --kernel=ir
IPython
What is now Jupyter was once a part of the IPython project. If your operating system doesn’t yet have Jupyter, but instead IPython version 3 packages (IPython 1 and 2 are not supported), you can substitute ipython
for jupyter
in above commands and it will work.