How to use psql with no password prompt?

You have four choices regarding the password prompt:

1. set the PGPASSWORD environment variable. For details see the manual:
   http://www.postgresql.org/docs/current/static/libpq-envars.html
2. use a .pgpass file to store the password. For details see the manual:
   http://www.postgresql.org/docs/current/static/libpq-pgpass.html
3. use "trust authentication" for that specific user:
   http://www.postgresql.org/docs/current/static/auth-methods.html#AUTH-TRUST
4. use a connection URI that contains everything:
   http://www.postgresql.org/docs/current/static/libpq-connect.html#AEN42532

A simple example with PGPASSWORD will be something like:

PGPASSWORD=YOUR_PASSRORD psql -h YOUR_PG_HOST -U YOUR_USER_NAME

Hope it helps.

Depending your account permissions, the example without specifying the database may fail, because user permissions are checked against the database you connect to. It is better explicitly specify the database too.

# this can fail.
PGPASSWORD=YOUR_PASSRORD psql -h YOUR_PG_HOST -U YOUR_USER_NAME    

# this is more likely to work, assuming given account has permissions to that database.
PGPASSWORD=YOUR_PASSRORD psql -h YOUR_PG_HOST -U YOUR_USER_NAME -d YOUR_DATABASE