bigdata@ubuntucmbigdata1:/opt/softwares/cm-5.6.0$ sudo ./cloudera-manager-installer.bin 

This installer always creates a new database, and will overwrite the existing database connection information for any existing installation. If you still want to use this installer, please remove the following file: /etc/cloudera-scm-server/db.properties

bigdata@ubuntucmbigdata1:/etc/cloudera-scm-server$ pwd
/etc/cloudera-scm-server
bigdata@ubuntucmbigdata1:/etc/cloudera-scm-server$ ll
total 32
drwxr-xr-x   2 cloudera-scm cloudera-scm  4096 Jun 26 12:39 ./
drwxr-xr-x 137 root         root         12288 Jun 26 12:33 ../
-rw-------   1 cloudera-scm cloudera-scm  1471 Jun 26 11:16 db.mgmt.properties
-rw-r--r--   1 cloudera-scm cloudera-scm   328 Jun 26 11:16 db.properties
-rw-r--r--   1 cloudera-scm cloudera-scm   714 Jun 26 11:16 db.properties.20170626-111628
-rw-r--r--   1 cloudera-scm cloudera-scm  2229 May 26 05:39 log4j.properties
bigdata@ubuntucmbigdata1:/etc/cloudera-scm-server$ sudo mv db.properties db.properties1
bigdata@ubuntucmbigdata1:/etc/cloudera-scm-server$ ll
total 32
drwxr-xr-x   2 cloudera-scm cloudera-scm  4096 Jun 26 12:41 ./
drwxr-xr-x 137 root         root         12288 Jun 26 12:33 ../
-rw-------   1 cloudera-scm cloudera-scm  1471 Jun 26 11:16 db.mgmt.properties
-rw-r--r--   1 cloudera-scm cloudera-scm   328 Jun 26 11:16 db.properties1
-rw-r--r--   1 cloudera-scm cloudera-scm   714 Jun 26 11:16 db.properties.20170626-111628
-rw-r--r--   1 cloudera-scm cloudera-scm  2229 May 26 05:39 log4j.properties
bigdata@ubuntucmbigdata1:/etc/cloudera-scm-server$