title: Not able to run Cassandra server on Ubuntu . Permission Denied error
body: <p>I am able to setup cassandra on ubuntu but when executing following command 
  paranjai is the user </p>
  
  <p><em>paranjai@ubuntu:~$ /etc/init.d/cassandra start</em> </p>
  
  <p>Following error is received</p>
  
  <p>cat: /var/run/cassandra.pid: Permission denied Cannot set group id for user ‘cassandra’
  Error validating user ‘cassandra’
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied
  cat: /var/run/cassandra.pid: Permission denied</p>
  
  <p>any help is appreciated . Thanks</p>