detect interactivity

[Roald de Vries]

On Dec 30, 2009, at 1:52 AM, Steven D'Aprano wrote:
> On Tue, 29 Dec 2009 16:09:58 +0100, Roald de Vries wrote:
>
>> Dear all,
>>
>> Is it possible for a Python script to detect whether it is running
>> interactively? It can be useful for e.g. defining functions that are
>> only useful in interactive mode.
>
> Ah, I should have looked more carefully at the docs...
>
> http://docs.python.org/library/sys.html#sys.ps1
>
> sys.ps1 and sys.ps2 are documented as only existing if you are running
> interactively.

This doesn't really work. In ipython, sys.ps1 is not defined. But also  
if I run 'python <<< "import sys; print(sys.ps1)"', I get an error.