It's a question better directed to the -general list.
You'll either want to specify the DB name and DB user in check_postgres invocation, or otherwise add an entry to pg_hba.conf, like: host ts nagios 192.168.122.1/32 trust
I need your help to resolve an issue psql: fe_sendauth: no password supplied which we are getting by nagios plugin , we are trying to monitor the disk space and via .pgpass for an authentication.