Psql

wikipedia:psql

• Ubuntu installation: apt install postgresql-client-12

sudo -u postgres psql
psql (10.12 (Ubuntu 10.12-0ubuntu0.18.04.1))
Type "help" for help.
postgres=#

psql --host=mypostgresql.c6c8mwvfdgv0.us-west-2.rds.amazonaws.com --port=5432 --username=awsuser --password --dbname=mypgdb 

psql -h localhost -U YOUR_USERNAME DB_NAME

psql -h <REMOTE HOST> -p <REMOTE PORT> -U <DB_USER> <DB_NAME>

if database is defined in .pg_service.conf you can use: 
psql service=MyDB

psql
psql: FATAL:  role "root" does not exist

su - postgres && psql
psql (10.12 (Ubuntu 10.12-0ubuntu0.18.04.1))
Type "help" for help.
postgres=#

sudo -u postgres psql
could not change directory to "/root": Permission denied
psql (12.6 (Ubuntu 12.6-0ubuntu0.20.04.1))
Type "help" for help.

psql
Warning: No existing cluster is suitable as a default target. Please see man pg_wrapper(1) how to specify one.
Error: You must install at least one postgresql-client-<version> package

FATAL: no pg_hba.conf entry for host "1x.1xx.2xx.1xx", user "your_username", database "your_db_name", SSL off

psql
psql: error: could not connect to server: No such file or directory
        Is the server running locally and accepting
        connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

psql service=pro
psql: error: could not connect to server: Connection refused
        Is the server running on host "your_rds_instance.eu-central-1.rds.amazonaws.com" (7.123.109.22) and accepting
        TCP/IP connections on port 5433 ?

Options

• Port (-p): psql -p 5432

Related terms

• pg_hba.conf (PostgreSQL Client Authentication Configuration File)
• apt install postgresql
• .psqlrc
• Connect to a database
• Show databases
• Create database
• Delete database
• Create user
• List users
• List databases
• List tables: show tables
• GRANT
• aws rds describe-db-instances

See also

• PostgreSQL: psql, .psqlrc, .pgpass, $HOME/.pg service.conf, -U, -W, -d, meta-commands: \du, \dg, \ddp, \dp, \list, \dn, \dt, \c, \l, \di, \q, show users, show, su - postgres, psql -c, \?, \connect, \conninfo, --version, --help, PL/pgSQL
• PostgreSQL: pg_dump, pg_restore, pgAdmin, pg_config, psql, pg_ctl, pg_isready, initdb, Role, Schema, DBeaver, Navicat, DataGrip, OmniDB, Adminer, docker-compose.xml PostgreSQL, PostgreSQL version, PostgreSQL logs, postgresql.conf, pg_hba.conf, $HOME/.pg_service.conf, Create database (PostgreSQL), Create user, createdb, GRANT, pg_stat, PostgreSQL VACUUM, EXPLAIN, pg stat activity, Autovacuum, ALTER DATABASE, PostgreSQL statistics collector, Shared buffers, EXPLAIN (PostgreSQL), EXPLAIN ANALYZE, Bitmap scan, EXPLAIN VERBOSE, EXPLAIN VERBOSE (PostgresSQL), WAL, ALTER USER, CREATE ROLE, CREATE USER, \du, show users, \l, The Statistics Collector, pganalyze, cron.schedule, Master, pg_tables, PostgreSQL replication, CREATE, SET, TOAST, PgBouncer, Restore DB, Index, meta-commands, Table, foreign table, Schema, Sequence, Views, materialized view, Table Partitioning, monitoring, PostgreSQL System Administration Functions, PostgreSQL extension, privileges, logging, PGTune, PostgreSQL parameter tunning, PostgreSQL modules, pgbench, PostgreSQL users, catalogs