Cannot use commands 'postgres' or 'pg_ctl'

Question

I am on Unix. I have got postgresql-9.3 installed.
When I want to start the server using pg_ctl or postgres, the terminal gives me:

The program 'postgres' is currently not installed. You can install it by typing:
sudo apt-get install postgres-xc

Can't I start the server without this postgres-xc?

Answer 1

This must be remnants of the postgres-xc package you had installed previously.

Since you just installed postgresql-9.3 and don't seem to have any databases in use, yet, I suggest to completely purge all postgres packages.

sudo apt-get purge postgresql-9.2
sudo apt-get purge postgresql-xc
...

Until there's nothing left:

dpkg -l | grep postgres

Then start from scratch. Your instance of pg_ctl seems to belong to the package postgres-xc. This should be gone after you've uninstalled the package. Find out with one of these commands:

dpkg -S pg_ctl
dlocate pg_ctl
apt-file search pg_ctl

pg_ctlcluster is provided by the package postgresql-common.
pg_ctl is provided by the package postgresql-9.3.

More about starting Postgres in the manual.