Temporarily bypass password authentication for the local postgres superuser on Linux to perform maintenance or reset credentials

Here is the standard procedure to temporarily bypass password authentication for the local postgres superuser on Linux to perform maintenance or reset credentials:

Step 1: Allow local passwordless trust in pg_hba.conf

Insert the trust rule at line 1 of the file so it takes priority over any subsequent md5 or scram-sha-256 directives:

Bash

sed -i '1i local   all             postgres                                trust' /var/lib/pgsql/data/pg_hba.conf

Step 2: Reload the configuration

Apply the changes to PostgreSQL without dropping existing client connections:

Bash

systemctl reload postgresql

Step 3: Connect without a password and set/reset credentials

Connect directly to the database engine as the postgres system user:

Bash

su - postgres -c "psql -U postgres"

Inside the interactive psql prompt, set your desired password:

SQL

ALTER USER postgres WITH PASSWORD 'YourStrongPasswordHere';
\q

Step 4: Restore password authentication (md5)

Revert line 1 back to password enforcement to secure local access:

Bash

sed -i 's/^local   all             postgres                                trust/local   all             postgres                                md5/' /var/lib/pgsql/data/pg_hba.conf
systemctl reload postgresql

Verification:

Confirm that local password enforcement is back in place:

Bash

grep -E "^local.*postgres" /var/lib/pgsql/data/pg_hba.conf

The output should show:

Plaintext

local   all             postgres                                md5