Thanks, Mark!
I am just following the Virtualenv Installation, up to the point when I run
pip install wheel mailman psycopg2-binary\<2.9 from within virtualenv.
This command runs a little time, eventually ending with (the following is printed about 5 or 6 times): ERROR: Command errored out with exit status 1: command: /opt/mailman/venv/bin/python3 -u -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-rdlaw8e1/lazr.delegates/setup.py'"'"'; __file__='"'"'/tmp/pip-install-rdlaw8e1/lazr.delegates/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' bdist_wheel -d /tmp/pip-wheel-049shc9h cwd: /tmp/pip-install-rdlaw8e1/lazr.delegates/ Complete output (6 lines): usage: setup.py [global_opts] cmd1 [cmd1_opts] [cmd2 [cmd2_opts] ...] or: setup.py --help [cmd1 cmd2 ...] or: setup.py --help-commands or: setup.py cmd --help
error: invalid command 'bdist_wheel'
ERROR: Failed building wheel for lazr.delegates
Running setup.py clean for lazr.delegates
Failed to build mailman authheaders authres lazr.config dkimpy lazr.delegates
Installing collected packages: wheel, atpublic, attrs, aiosmtpd, six, python-dateutil, python-editor, sqlalchemy, MarkupSafe, Mako, alembic, authres, dnspython, dkimpy, publicsuffix2, authheaders, click, falcon, zope.interface, flufl.bounce, flufl.i18n, psutil, flufl.lock, gunicorn, zipp, importlib-resources, nose, lazr.delegates, lazr.config, passlib, urllib3, certifi, idna, charset-normalizer, requests, zope.event, zope.hookable, zope.component, zope.i18nmessageid, zope.schema, zope.configuration, mailman, psycopg2-binary
ERROR: Could not install packages due to an EnvironmentError: [Errno 13] Permission denied: '/opt/mailman/venv/lib/python3.8/site-packages/wheel-0.37.1.dist-info'
Consider using the --user option or check the permissions.
Did I miss to grant some permissions to the "mailman" user/group?