If you use pg_dump and get this error:

pg_dump: server version: <version>; pg_dump version: <version>
pg_dump: aborting because of server version mismatch

Then do the following. Find the pg_dump that comes with the postgresql:

locate pg_dump

You may get something like this:

/usr/bin/pg_dump
/usr/pgsql-<postgresql-version>/bin/pg_dump

Create a symlink to the server version:

sudo ln -s /usr/pgsql-<postgresql-version>/bin/pg_dump /usr/bin/pg_dump --force

Try pg_dump again.