fe_sendauth：未提供密码

database.yml：

# SQLite version 3.x
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem 'sqlite3'
development:
  adapter: postgresql
  encoding: utf8
  database: sampleapp_dev  #can be anything unique
  #host: localhost
  #username: 7stud
  #password: 

  #adapter: sqlite3
  #database: db/development.sqlite3
  pool: 5
  timeout: 5000

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  adapter: postgresql
  encoding: utf8
  database: sampleapp_test  #can be anything unique
  #host: localhost
  #username: 7stud
  #password: 
  #adapter: sqlite3
  #database: db/test.sqlite3
  pool: 5
  timeout: 5000

production:
  adapter: postgresql
  database: sampleapp_prod   #can be anything unique
  #host: localhost
  #username: 7stud
  #password: 
  #adapter: sqlite3
  #database: db/production.sqlite3
  pool: 5
  timeout: 5000

pg_hba.conf：

# TYPE  DATABASE        USER            ADDRESS                 METHOD

# "local" is for Unix domain socket connections only
local   all             all                                     trust
# IPv4 local connections:
host    all             all             127.0.0.1/32            trust
# IPv6 local connections:
host    all             all             ::1/128                 trust
# Allow replication connections from localhost, by a user with the
# replication privilege.
#local   replication     postgres                                md5
#host    replication     postgres        127.0.0.1/32            md5
#host    replication     postgres        ::1/128                 md5

我将前三行中的METHOD从md5更改为trust，但是仍然收到错误。

而且无论执行什么操作时，我在database.yml中尝试执行的操作如何：

~/rails_projects/sample_app4_0$ bundle exec rake db:create:all

我总是得到错误：

fe_sendauth：未提供密码

我按照本教程进行了设置：

https://pragtob.wordpress.com/2012/09/12/setting-up-postgresql-for-ruby-on-rails-on-linux

Mac OSX 10.6.8
PostgreSQL 9.2.4 installed via enterpriseDB installer
Install dir: /Library/PostgreSQL/9.2

对pg_hba.conf或postgresql.conf文件进行更改后，需要重新加载群集以获取更改。

从命令行： pg_ctl reload

从数据库中（以超级用户身份）： select pg_reload_conf();

在PGAdmin中：右键单击数据库名称，选择“重新加载配置”

注意：重新加载不足以进行更改，例如启用存档，更改shared_buffers等-那些需要重新启动集群的更改。

我只是将--password标志放入命令中，然后按Enter键，它要求我提供密码。

如果未提供数据库密码，则会发生这种情况。

default="postgres://postgres:password@127.0.0.1:5432/DBname"