postgres: could not find the database system

If I try to run the postgres command, I get:

2020-12-29 00:14:53.213 GMT  LOG:  skipping missing configuration file "/usr/local/pgsql/data/postgresql.auto.conf"
postgres: could not find the database system
Expected to find it in the directory "/usr/local/pgsql/data",
but could not open file "/usr/local/pgsql/data/global/pg_control": No such file or directory

**How can I find out what config file is telling postgres to look at /usr/local/pgsql/data?** In my case, postgres was installed on OSX via Homebrew.