title: Issue in installing oracle 18cxe on ubuntu 18.04
body: <p>I am trying to configure Oracle XE but am facing the below issue:</p>
  
  <blockquote>
    <p>root@venky-Lenovo-G510:~# /etc/init.d/oracle-xe-18c configure</p>
    
    <p>/bin/df: unrecognized option '--direct' 
       Try '/bin/df --help' for more information.
       Specify a password to be used for database accounts.
       Oracle recommends that the password entered should be at least 8
       characters in length, contain at least 1 uppercase character, 1 lower</p>
    
    <p>case character and 1 digit [0-9]. Note that the same password will be</p>
    
    <p>used for SYS, SYSTEM and PDBADMIN accounts:
       Confirm the password:
       Configuring Oracle Listener. Listener configuration succeeded.
       Configuring Oracle Database XE.
       ****[FATAL] [DBT-50000] Unable to check for available memory.****</p>
    
    <p>Database configuration failed. Check logs under
    '/opt/oracle/cfgtoollogs/dbca'.</p>
    
    <p>root@venky-Lenovo-G510:~#</p>
  </blockquote>
  
  <p>Is this anything related to <code>/bin/df: unrecognized option '--direct'</code> ?
  Or something else ?</p>
  
  <p>Thanks </p>