How do I connect to psql when it cannot connect to the server? - postgresql

Question

When I typed psql in the terminal I get the below:
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/pgsql_socket/.s.PGSQL.5432"?
My brew services list shows that Postgres is running:
postgresql#9.5 started john doe /Users/johndoe/Library/LaunchAgents/homebrew.mxcl.postgresql#9.5.plist

Answer 1

Run this to determine, where is your cluster data directory (the directory, where Postgres keeps data, WAL logs, etc):
sudo ps ax | grep postgres | grep D
If Postgres is running, you will see smth like this (this is Postgres.app, not Homebrew version, but it should be similar):
Nikolays-MacBook-Pro:~ nikolay$ sudo ps ax | grep postgres | grep D
Password:
599 ?? S 0:00.06 /Users/nikolay/PostgreSQL/pg96/bin/postgres -D /Users/nikolay/PostgreSQL/data/pg96 -r /Users/nikolay/PostgreSQL/data/logs/pg96/postgres.log
Go to the cluster directory ("/Users/nikolay/PostgreSQL/data/pg96" in this example) and open postgresql.conf, it should be there.
You need to find, what is set in the following options in your postgresql.conf:
listen_addresses
port
These two configurations tell you, on which network interfaces and which port Postgres is sitting.
In most cases, they are like this:
listen_addresses = '*'
port = 5432
There is additional config files, pg_hba.conf, you can consider it like an "internal firewall" for Postgres -- check rules, that are inside, and if needed, edit them. Remember, that if you edit any of connection settings, Postgres needs to be restarted.
In this case, to connect to Postgres, you need:
psql -h localhost -p 5432 -U postgres template1
Here I assumed that you installed Postgres under "postgres" OS user and during installation the corresponding database user was created. Probably you need to try different way:
psql -h localhost -p 5432 -U yourname template1
-- template1 is a default database which is a template for all DBs you will create, so you can try to connect to it anytime. "yourname" is your MacOS username.
Of course, "-p 5432" can be omitted because 5432 is Postgres' default port.
"-U yourname" can be also omitted -- in this case psql will take your OS username and use it like a DB username. And you can omit DB name also if it is the same as database username. So in some cases, "psql -h localhost" will work.
Hope it helps.