title: Postgres: authentication fails when try to login with different unix user
body: <p>I have a user <code>hduser</code> and user <code>postgres</code>,</p>
  
  <p>with <strong>hduser</strong>:</p>
  
  <pre><code>hduser@master:/$ psql -Upostgres -W analytics
  Password for user postgres: 
  psql: FATAL:  Ident authentication failed for user "postgres"
  hduser@master:/$ 
  </code></pre>
  
  <p>with <strong>postgres</strong>:</p>
  
  <pre><code>postgres@master:/opt/pentaho/biserver-ce$ psql -Upostgres -W analytics
  Password for user postgres: 
  psql (8.4.9)
  Type "help" for help.
  
  analytics=# 
  </code></pre>
  
  <p>How can I login to same database with a different user like <code>hduser</code> or some other?  </p>
  
  <p>Thank you</p>