OS: Marcel has been built and tested on Linux. It seems to mostly work on Mac, except for the ps operator. (Actually, ps might work now, because I changed the implementation to use psutil, instead of relying on the /proc filesystem.) Haven't tried Windows at all.
Python: 3.6 or higher. 3.x for x slightly less than 6 might work, haven't tried it.
sudo python3 -m pip install --prefix /usr/local marcel
This installs to your system, and makes marcel available to all users. Modify /usr/local if you want to install elsewhere. Leave off sudo and --prefix /usr/local if you want to install just for yourself, in your home directory. In that case, the executable will be in the bin directory.
Database access is currently limited to Postgres through the psycopg2 driver. If you want to use marcel to do database access, via the sql command, then you will need to install Postgres and psycopg2.
To run marcel:
All documentation is available through the help command.