Psql could not connect to server: No such file or directory, 5432 error?

Question

I'm trying to work on the psql on my Vagrant machine, but I get this error:

psql: could not connect to server: No such file or directory

My server is running locally and accepting connections on 

Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?

Note: Vagrant 1.9.2 Box: ubuntu/trusty64, 

EDIT The Commands I have used to install and run Postgres:

sudo apt-get update

sudo apt-get install postgresql

sudo su postgres

psql -d postgres -U postgres

Answer 1

Even I had the same issue, related to the configuration of my pg_hba.conf file (located in /etc/postgresql/9.6/main). Kindly note that I am using version 9.6 in the Postgresql.

The error is related to some misconfiguration of Postgresql, which is causing the server to crash before it starts.

You can try these instructions:

Confirm that your Postgresql service is running, using sudo service PostgreSQL start

Run pg_lsclusters from your terminal

Check what is the cluster you are running, the output should be something like:

Version - Cluster Port Status Owner Data directory

9.6 ------- main -- 5432 online postgres /var/lib/postgresql/9.6/main

Disregard that '---' signs, as they are being used, only for alignment. The important information is the version and the cluster. You can also check whether the server is running or not in the status column.

Copy your info from the version siaplayed and the cluster, and use like so: pg_ctlcluster <version> <cluster> start, so in my case, using version 9.6 and cluster 'main', it would be pg_ctlcluster 9.6 main start

If something is wrong, then Postgresql will generate a log, that can be accessed on /var/log/postgresql/postgresql-<version>-main.log, so in my case, the full command would be 

sudo nano /var/log/postgresql/postgresql-9.6-main.log.

The output should show what is the error.

2017-07-13 16:53:04 BRT [32176-1] LOG: invalid authentication method "all"

2017-07-13 16:53:04 BRT [32176-2] CONTEXT: line 90 of configuration file "/etc/postgresql/9.5/main/pg_hba.conf"

2017-07-13 16:53:04 BRT [32176-3] FATAL: could not load pg_hba.conf

1. Fix the errors and restart your postgresql service through sudo service postgresql restart and it should be fine.

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