Opsmop uses policy files written in a pure-Python DSL. The command line simply loads a policy file and runs it.
See Language for more about the contents of those files.
Check mode runs a policy and reports on actions that should be changed, but does not make any changes (use Apply Mode to make changes). This is often called a ‘dry-run’ mode, and dry-run support is a first-class citizen of OpsMop:
cd opsmop-demo/content python3 hello.py --check --local
To just look for missing files and bad parameters, without running the full check mode, you can also run:
cd opsmop-demo/content python3 hello.py --validate --local
Apply mode runs a policy, plans what changes are needed, and also runs the policy:
cd opsmop-demo/content python3 hello.py --apply --local