pylab: The pylab switch automatically imports all the SciPy, NumPy, and matplotlib packages. Without this switch, we would have to import these packages ourselves.

All we need to do is enter the following instruction on the command line:

$ ipython --pylab
Type "copyright", "credits" or "license" for more information.

IPython 2.4.1 -- An enhanced Interactive Python.
?         -> Introduction and overview of IPython's features.
%quickref -> Quick reference.
help      -> Python's own help system.
object?   -> Details about 'object', use 'object??' for extra details.

Welcome to pylab, a matplotlib-based Python environment [backend: MacOSX].
For more information, type 'help(pylab)'.

In [1]: quit()
quit() or Ctrl + D quits the IPython shell.

Saving a session: We might want to be able to go back to our experiments. In IPython, it is easy to save a session for later use. This is done with the following command:

In [1]: %logstart
Activating auto-logging. Current session state plus future input saved.
Filename       : ipython_log.py
Mode           : rotate
Output logging : False
Raw input log  : False
Timestamping   : False
State          : active

Logging can be switched off using this command:

In [9]: %logoff
Switching logging OFF

Executing a system shell command: You can execute a system shell command in the default IPython profile by prefixing the command with the ! symbol. For instance, the following input will get the current date:

In [1]: !date

In fact, any line prefixed with ! is sent to the system shell. We can also store the command output, as shown here:

In [2]: thedate = !date
In [3]: thedate

Displaying history: We can show the history of commands with the %hist command, like this:

In [1]: a = 2 + 2

In [2]: a
Out[2]: 4

In [3]: %hist
a = 2 + 2
a
%hist

This is a common feature in Command-line Interface (CLI) environments. We can also look up the history with the -g switch:

In [5]: %hist -g a = 2
    1: a = 2 + 2

IPython as a system shell from the official IPython website at http://ipython.org/ipython-doc/dev/interactive/shell.html