CODE EXAMPLE FOR SHELL

psql: error: FATAL: Peer authentication failed for user

# The problem is still your pg_hba.conf file*.
# This line:
local   all             postgres                                peer
# Should be:
local   all             postgres                                md5
# After altering this file, don't forget to restart 
# your PostgreSQL server. If you're on Linux, 
# that would be sudo service postgresql restart.