Experimental Physics and
Industrial Control System

Pete Jemian <[email protected]> · Mon, 30 Jan 2017 12:49:03 -0600

Alan:

You reported a Python 2.7 error when loading PyEpics from a

non-interactive Linux session:

>   File
> "/home/akastengren/anaconda2/lib/python2.7/site-packages/epics/ca.py",
> line 217, in initialize_libca
>     raise ChannelAccessException('loading Epics CA DLL failed: ' +
> str(exc))
> epics.ca.ChannelAccessException: loading Epics CA DLL failed:
> /home/akastengren/anaconda2/bin/../lib/libreadline.so.6: undefined
> symbol: PC

user@host ~$ nm /home/akastengren/anaconda2/lib/libreadline.so.6 | grep PC
                     U PC

The "U" means the symbol is undefined

I get the same thing (with my Anaconda installations). This is an

Anaconda Python issue with the readline support. The closest web answer

I can find is here:

http://stackoverflow.com/questions/29944238/importerror-when-using-rpy2-with-numpy-testing

The selected "best" answer describes three steps as the suggested fix:

1. delete __pycache__ directory (does not apply, you have Python 2.7,

not Python3

2. conda install -c asmeurer readline
3. Inside the .py file, add "import readline"

Step 2, do it from the command line.  Updates readline to 6.2.5
Step 3, insert this into epics/ca.py at (or near) line 26
(/home/akastengren/anaconda2/lib/python2.7/site-packages/epics/ca.py)

Report back whether or not this helps.

Pete

--
----------------------------------------------------------
Pete R. Jemian, Ph.D.                <[email protected]>
Beam line Controls and Data Acquisition, Group Leader
Advanced Photon Source,   Argonne National Laboratory
Argonne, IL  60439                   630 - 252 - 3189
-----------------------------------------------------------
   Education is the one thing for which people
      are willing to pay yet not receive.
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System