detect interactivity

[Steven D'Aprano]

On Wed, 30 Dec 2009 03:26:20 +0100, Roald de Vries wrote:

> 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.

Then ipython is not a valid implementation of Python, since it breaks a 
promise of the language. You should report this to the ipython people as 
a serious bug.


> But also
> if I run 'python <<< "import sys; print(sys.ps1)"', I get an error.

Of course you do, because you're not running interactively and so sys.ps1 
doesn't exist. You need to check the existence of ps1:

try:
    sys.ps1
except AttributeError:
    print "Not running interactively."
else:
    print "Running interactively."


Alternatively:

if hasattr(sys, 'ps1'):
    print "Running interactively."
else:
    print "Not running interactively."



-- 
Steven