How to find out if oracle_home installation is RAC enabled or not?

For AIX :-
$ cd $ORACLE_HOME/rdbms/lib
$ nm -r libknlopt.a | grep -c kcsm.o

For 64 bit AIX :-

$ cd $ORACLE_HOME/rdbms/lib
$ nm -X 64 -r libknlopt.a | grep -c kcsm.o

For Other UNIX :-

$ cd $ORACLE_HOME/rdbms/lib
$ ar -t libknlopt.a | grep -c kcsm.o

If above command returns 0, then RAC is not linked.If it returns more than 0, then it is linked.

Other options :-
RAC - {kcsm.o}
RAT - {kecwr.o}
OLS - {kzlibac.o}
DV - {kzvidv.o}
ASM - {kfon.o}
OLAP - {xsyeolap.o}
PART - {kkpoban.o}
CTX - {kciwcx.o}