Configure the environment -- env.sh

cp env.sh.example env.sh
chmod 600 env.sh

env.sh holds secrets and per-environment values; it is gitignored and mode 600 because live credentials go in it. An unedited copy is enough to try everything locally -- with no deploy target configured, uploads are skipped (logged, not an error).

The one value worth knowing about right away is SITE_BASE_URL: the canonical URL normally comes from site.base_url in config/site.yml (step 2), and this env.sh value overrides it when set -- it exists so a staging or local environment can point somewhere other than production while building from the same config. One site, one URL? Set site.base_url and leave this out.

Watch the order they start in: the example above ships SITE_BASE_URL active and pointing at https://example.com, so filling in site.base_url carefully and leaving this file alone gives a site that still calls itself example.com in its feed, its sitemap and every share preview. Either comment this line out or give it the same address. ./setup.sh writes both to the same value for exactly this reason, and ./blog.sh doctor reports the address that would actually be used rather than the one in the config.