How to change oracle dba group in unix

cd $ORACLE_HOME/rdbms/lib
cat config.[cs]
The line '#define SS_DBA_GRP "group"' should name the chosen DBA group. If you wish to change the DBA group change the group name shown in this file. Eg: Change:
#define SS_DBA_GRP "dba" to:
#define SS_DBA_GRP "mygroup"
To effect any changes to the DBA group and to be sure you are using the group defined in this file relink the Oracle executable as below. Be sure to shutdown all databases before relinking:
rm config.o
make -f ins_rdbms.mk config.o ioracle