Python virtual environments on z/OS

Virtual environments are very useful as they allow you to test install components without affecting the shared libraries.

You create an environment called env with

python3 -m venv env

but this gave

Error: Command ‘Ý’/u/py/env/bin/python3’, ‘-Im’, ‘ensurepip’, ‘–upgrade’, ‘–default-pip’¨’ returned non-zero exit status 1.

I think this was because my z/OS had no direct network connection. However

python3 -m venv –without-pip env –system-site-packages

worked. I needed the –system-site-packages, so I could build the extension.

Activate the environment

The instruction said use the command env/bin/activate but this failed

env/bin/activate: FSUM9209 cannot execute: reason code = ef076015: EDC5111I Permission denied.

but

. env/bin/activate

worked. (Just . env/b*/a* worked for me.)

If you get
 FSUM7332 syntax error: got Word, expecting )    

You need to issue the command ( or put it in your .profile)

export _BPXK_AUTOCVT=ON

See here. (_BPXK_AUTOCVT Used when enabling automatic conversion of tagged files).

To get out of the virtual environment use

deactivate

To delete the environment

remove the directory

rm -r env

Use the environment

You should now be able to use the environment.

You should check that the HOME environment variable is a directory with read/write access.

You may want to set up PYTHONHOME for special python packages.