ORA-01031: insufficient privileges while doing sqlplus / as sysdba

I copied one oracle home to some other server/mount and did the clone of binaries. After completion when I was trying to log in to SQL as sysdba to create database here.

There I found following message.

Error

$sqlplus '/ as sysdba'

SQL*Plus: Release 11.2.0.3.0 Production on Fri Feb 7 05:12:22 2014

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

ERROR:
ORA-01031: insufficient privileges

Enter user-name:

Looking like some permission issue. Checked the user and OS permission of files, which were looking OK.
SQLNET.ORA too looked ok, then found following.

Reason

Running clone on binaries has overwritten $ORACLE_HOME/rdbms/lib/config.c, and it was missing group values.

#define SS_DBA_GRP ""
#define SS_OPER_GRP ""

Solution

Changed it to

#define SS_DBA_GRP "oinstall"
#define SS_OPER_GRP "oinstall"


Then run $ORACLE_HOME/bin/relink.

On completion, 

$sqlplus '/ as sysdba'

SQL*Plus: Release 11.2.0.3.0 Production on Fri Feb 7 07:02:55 2014

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to an idle instance.

SQL>