enable RAC in an ORACLE_HOME

just noticed that there is a template script in the GI_HOME to enable RAC:

cat $GI_HOME/crs/config/relink_rac_on
#!/bin/sh
#
MAKE=/usr/bin/make
ECHO=/bin/echo
if [ $# -lt 1 ]; then
  $ECHO "Usage: relink_rac_on "
  exit 1
fi
ORACLE_HOME=$1
if [ $# -gt 1 ]; then
  MAKE=$2
else
  $ECHO "Make path has not been passed from command line."
fi
$ECHO "Checking for writable permission on $ORACLE_HOME/lib and $ORACLE_HOME/bin."
if [ -w $ORACLE_HOME/bin -a -w $ORACLE_HOME/lib ]; then
  $ECHO "running rac_on make target.."
  $MAKE -f $ORACLE_HOME/rdbms/lib/ins_rdbms.mk ORACLE_HOME=$ORACLE_HOME rac_on ioracle
  exit $?
else
  $ECHO "$ORACLE_HOME/lib and $ORACLE_HOME/bin directories are not writable, hence skipping relink operation."
fi
exit 0

this can be useful if you installed the ORACLE_HOME without enabling RAC and want to turn it on afterwards …