Experimental Physics and
Industrial Control System

This should be LD_LIBRARY_PATH.  You were able to find epicsCA which is the Python part of things.  libca is the epics library which does not have anything to do with Python.
Also, for what it is worth, I have also been working to update Geoff Savage's CaPython.  This does not provide quite as slick an interface as Matt's but it is  a pretty full implementation of the Channel Access Libraries.  I have most of this working using a newer version of SWIG and python.  I have not yet added the 3.14 CA calls but it can do things like deal with larger arrays.  I am trying to coordinate with Geoff before releasing this.

John

Tim Mooney wrote:

Adam,  The first thing I'd try is setting either the LD_LIBRARY_PATH,
or the PYTHONPATH, environment variable to the directory containing the
needed .so file.  E.g.:

setenv LD_LIBRARY_PATH /usr/local/lib/epics/base/lib/linux-x86_64
  or, if you're using bash,
export LD_LIBRARY_PATH=/usr/local/lib/epics/base/lib/linux-x86_64


Adam Kadzban wrote:

Hey all, I'm a relative newcomer to both Linux, Python, and Epics, so sorry if this has an easy solution.  I guess I'm not even sure if it's a problem with Epics itself, or Python, or something else.  I'm having some problems getting Python to import the EpicsCA module.  I'm running Ubuntu 8.04 (Hardy), and it's an x86_64 system.  The epics base seems to have installed fine, I put it in /usr/local/lib/epics/base.  I got the epics module here <http://cars9.uchicago.edu/%7Enewville/Epics/Python/> (http://cars9.uchicago.edu/~newville/Epics/Python/), and again it looked like it installed fine to /usr/local/EpicsCA-2.1.5.

The problem is, whenever I try to do anything with EpicsCA in Python, it dies on me because it can't find libca.so.  Here's what it shows when I try to import EpicsCA:

 >>> import EpicsCA
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
 File "/usr/lib/python2.5/site-packages/EpicsCA/__init__.py", line 116, in <module>
   import _epics
ImportError: libca.so: cannot open shared object file: No such file or directory

(it does the same if I try "from EpicsCA import *")

However, I know libca.so exists, it's here:

adam:$ locate libca.so
/usr/local/lib/epics/base/lib/linux-x86_64/libca.so
/usr/local/lib/epics/base/lib/linux-x86_64/libca.so.3.14
/usr/local/lib/epics/base/src/ca/O.linux-x86_64/libca.so.3.14

So there it is, in the epics base folder.  Why can't Python find it?  I was digging around online, and found how to add places for Python looks for modules to import them (though I don't think that's the problem, because it can't find libca.so, not a module), and I added a bunch of places, to no avail.  Anyone have any ideas?


Not sure if it's relevant, but when I ran the setup.py script to install EpicsCA, I had to edit the environment variable manually.  I added "EPICS_BASE=/usr/local/lib/epics/base" to /etc/environment, but for some reason os.environ['EPICS_BASE'] wasn't finding /usr/local/lib/epics/base.  I had to change the setup script to look there.  Though if I opened a Python interpreter and printed os.environ['EPICS_BASE'], it came out as /usr/local/lib/epics/base.  So something fishy was going on there, not sure if it's related though.


Thanks,
Adam Kadzban

--

John Hammonds
Beamline and Data Acquisition Group
APS Engineering Support Division

Argonne National Laboratory
[email protected] <mailto:[email protected]>
(630)252-5317