sudo apt-get update
sudo apt-get -y upgrade
```bash

After we upgrade our base system, now it's time to install PostgreSQL 14.

Since Ubuntu 20.04 doesn't have PostgreSQL 14 in [its repository][4], we need to add oficial PostgreSQL repository so we can install PostgreSQL 14.

## Step 2 — Import Repository Signing Key {#h-step-2-import-repository-signing-key}

The PostgreSQL team is using GPG to sign downloadable packages from the PostgreSQL website.

We add PostgreSQL public GPG key so apt can verify that packages downloaded from PostgreSQL repository are not tampered or corrupt.

Add PostgreSQL GPG public key using the command below.

```bash
wget --quiet -O - https://www.postgresql.org/media/keys/ACCC4CF8.asc | sudo apt-key add -

echo "deb http://apt.postgresql.org/pub/repos/apt/ $(lsb_release -cs)-pgdg main" | sudo tee /etc/apt/sources.list.d/postgresql-pgdg.list > /dev/null
```bash

Refresh apt metadata using the command below.

```bash
sudo apt-get update

sudo apt-get install postgresql-14
```bash

Alternative method to install PostgreSQL 14 on Ubuntu 20.04 is using apt command

```bash
sudo apt install postgresql-14

dpkg -l | grep postgresql
```bash

## Check PostgreSQL 14 Listening Ports {#h-check-postgresql-14-listening-ports}

By default, PostgreSQL listens on port 5432. We can use netstat to check whether there is a process listening on port 5432.

```bash
sudo netstat -naptu | grep 5432

sudo netstat -naptu | grep postgres
```bash

Alternative to `netstat`, We can use `ss` command below to check whether there is a process listen on PostgreSQL default port 5432.

```bash
sudo ss -atnp | grep 5432

sudo ss -atp | grep postgres
```bash

The last output above shows there is also a connection to ephemeral UDP port from local. According to this thread on PostgreSQL mailing lists, this is a PostgreSQL stats collector that uses UDP to send and receive stats data locally.

## Checking PostgreSQL Process {#h-checking-postgresql-process}

We can ue `ps` command to check what processes currently running with name contain postgres.

```bash
ps -aux | grep postgres

top -u postgres
```bash

## Managing PostgreSQL 14 Services on Ubuntu 20.04 {#h-managing-postgresql-14-services-on-ubuntu-20-04}

Check `postgres` service status using command below.

```bash
sudo service postgresql status

sudo systemctl status postgresql
```bash

Using both commands above you see `active (exited)` on the `Active:` line. This happens because systemd doesn't know the status of each PostgreSQL cluster running on the instance. One instance/installation of PostgreSQL can run multiple clusters of PostgreSQL.

We can check, list of PostgreSQL clusters running on our machine using the command below.

```bash
pg_lsclusters

sudo service postgresql@14-main status
```bash

As an alternative to service, we can use systemctl to check this cluster status.

```bash
sudo systemctl status postgresql@14-main

sudo systemctl stop postgresql
```bash

Start PostgreSQL service using the command below.

```bash
sudo systemctl start postgresql

sudo systemctl restart postgresql
```bash

Reload PostgreSQL service using the command below.

```bash
sudo systemctl reload postgresql

sudo su - postgres
```bash

After switching to postgres user, we can connect using `psql` command.

To list all databases in PostgreSQL we can use `\l` command.

To list all users in PostgreSQL we can use `\du` command.

To exit from `psql` we can use `\q` command.

To exit from `postgres` user type `exit` or `CTRL+D`

## Change postgres User Password {#h-change-postgres-user-password}

Now we're on our own linux user. Let's try to login to `localhost` or `127.0.0.1`.

```bash
$ psql -U postgres -W -h 127.0.0.1
Password for user postgres: 

psql: fe_sendauth: no password supplied
```bash

Since we cannot login without providing password, we set new password for `postgres` user. Change user to `postgres` user like shown above and use psql to connect to PostreSQL.

After logging in, type `\password`. Enter new password and confirmation password for user `postgres`.

When we login again to `localhost` or `127.0.0.1` and provide a password, we can log in successfully.

## Uninstall PostgreSQL 14 from Ubuntu 20.04 {#h-uninstall-postgresql-14-from-ubuntu-20-04}

In this section, we learn how to uninstall PostgreSQL 14 and its dependencies on Ubuntu 20.04 completely.

Please be careful when running steps in this section since this will stop your PostgreSQL database server.

Use the command below to uninstall all PostgreSQL 14 packages, both server, and client.

```bash
sudo apt-get remove postgresql-14 \
    postgresql-client-14 \
    postgresql-client-common \
    postgresql-common

rm -rf /var/lib/postgresql/
```bash

Remove PostgreSQL 14 configuration directories using the command below.

```bash
rm -rf /etc/postgresql
rm -rf /etc/postgresql-common