If your workflow source is version controlled cylc install
records information from the version control system in ~/cylc-run/workflow/log/version
.
For example if you wanted to run an experiment you might do:
git checkout -b experiment1
# make changes to your workflow
git commit --all --message "experiment1"
cylc install . --run-name experiment1
Then the commit hash of the changes you made will be available in ~/cylc-run/workflow/experiment1/log/version/vcs.json
.
Alternatively, you could choose not to commit your changes, and you would be able to view them at ~/cylc-run/workflow/experiment1/log/version/uncommitted.diff
.