How to dump data owned by postgres in case of lack of privileges for writing

Question

I have DB owned by postgres, and I need to dump it, but postgres user does not have rights to write. So it boils down to login to DB as postgres but under different user in OS. How can I do that? I tried -U postgres but get an error even without password prompt. Basically I seek for `mysql -u root -p' in Postgres.

Answer 1

Dump to the standard output, and have another OS user write to the file.

Assuming you're root:

# (su postgres -c 'pg_dump -U postgres dbname') > /path/to/backup.sql

The resulting file will created and written by root.