Finding SAGE_ROOT?

[Paul Graham]

In trying to setup development for the Sage Notebook, by following the guide at: http://www.sagemath.org/doc/developer/sagenb/index.html , you first need to locate the root directory of the Sage installation, SAGE_ROOT . Thats the part where im stuck as i dont know where SAGE_ROOT is... Many other places make reference to this place, not just the notebook. So kind of a general dev issue. Im on ubuntu and have a development directory, just containing the sage repository at : ~/sage , and have what is supposed to be a non-development working stable installation of sage  that was installed using the "UBUNTU PPA" instructions at http://www.sagemath.org/download-linux.html, just:

sudo apt-add-repository -y ppa:aims/sagemath
sudo apt-get update
sudo apt-get install sagemath-upstream-binary

Im not sure where this installs to, what the default installation directory is on ubuntu, or if sage installs somewhere different? If i do:

user1@computer0:~$ ./sage
bash: ./sage: Is a directory

but but if i do:

user1@computer0:~$ sage
┌────────────────────────────────────────────────────────────────────┐
│ Sage Version 6.3, Release Date: 2014-08-10                         │
│ Type "notebook()" for the browser-based notebook interface.        │
│ Type "help()" for help.                                            │
└────────────────────────────────────────────────────────────────────┘
/usr/lib/sagemath/local/lib/python2.7/site-packages/IPython/utils/path.py:310: UserWarning: IPython dir '/home/user1/.sage/ipython-2.1.0' is not a writable location, using a temp directory.
  " using a temp directory."%ipdir)
sage:

I dont know what the difference between "sage" and "./sage" is, but maybe above info will help someone pinpoint where my SAGE_ROOT is? I tried alot of searching but no luck so far.

[William A Stein]

Try typing SAGE_ROOT at the sage prompt, e.g.,

sage: SAGE_ROOT
'/usr/local/sage/sage-6.2.rc2'

William Stein
Professor of Mathematics
University of Washington
http://wstein.org
wst...@uw.edu