“root” execution of the PostgreSQL server is not p

Question

When I try to start postgresql I get an error:

postgres

postgres does not know where to find the server configuration file.
You must specify the --config-file or -D invocation option or set the PGDATA environment variable.

So then I try to set my config file:

postgres -D /usr/local/var/postgres

And I get the following error:

postgres cannot access the server configuration file "/usr/local/var/postgres/postgresql.conf": Permission denied

Hmm okay. Next, I try to perform that same action as an admin:

 sudo postgres -D /usr/local/var/postgres

And I receive the following error:

"root" execution of the PostgreSQL server is not permitted.
The server must be started under an unprivileged user ID to prevent possible system security compromise. See the documentation for more information on how to properly start the server.

I googled around for that error message but cannot find a solution.
Can anyone provide some insight into this?

Answer 1

For those trying to run custom command using the official docker image, use the following command. docker-entrypoint.sh handles switching the user and handling other permissions.

docker-entrypoint.sh -c 'shared_buffers=256MB' -c 'max_connections=200'

Answer 2

Your command does not do what you think it does. To run something as system user postgres:

 sudo -u postgres command

To run the command (also named postgres!):

sudo -u postgres postgres -D /usr/local/var/postgres

Your command does the opposite:

sudo postgres -D /usr/local/var/postgres

It runs the program postgres as the superuser root (sudo without -u switch), and Postgres does not allow to be run with superuser privileges for security reasons. Hence the error message.

If you are going to run a couple of commands as system user postgres, change the user with:

sudo -u postgres -i

... and exit when you are done.

• PostgreSQL error: Fatal: role "username" does not exist

If you see this error message while operating as system user postgres, then something is wrong with permissions on the file or one of the containing directories.

postgres cannot access the server configuration file "/usr/local/var/postgres/postgresql.conf": Permission denied /usr/local/var/postgres/postgresql.conf

In closing:

• Consider instruction in the Postgres manual.
• Also consider the wrapper pg_ctl - or pg_ctlcluster in Debian-based distributions.
• And know the difference between su and sudo.