You are installing 11gR2 11.2.0.1 Grid Infrastructure on Red Hat 6, CentOS 6 or similar Linux operating system, and right at the very end of the process, the root.sh script blows up with a really odd error:

[root@localhost oraInventory]# cd /u01/app/oracle/product/11.2.0/db_1
[root@localhost db_1]# ./root.sh
Running Oracle 11g root.sh script...

The following environment variables are set as:
    ORACLE_OWNER= oracle
    ORACLE_HOME=  /u01/app/oracle/product/11.2.0/db_1

Enter the full pathname of the local bin directory: [/usr/local/bin]: 
   Copying dbhome to /usr/local/bin ...
   Copying oraenv to /usr/local/bin ...
   Copying coraenv to /usr/local/bin ...

Creating /etc/oratab file...
Entries will be added to the /etc/oratab file as needed by
Database Configuration Assistant when a database is created
Finished running generic part of root.sh script.
Now product-specific root actions will be performed.
2012-11-05 18:13:18: Checking for super user privileges
2012-11-05 18:13:18: User has super user privileges
2012-11-05 18:13:18: Parsing the host name
Using configuration parameter file: /u01/app/oracle/product/11.2.0/db_1/crs/install/crsconfig_params
Creating trace directory
/u01/app/oracle/product/11.2.0/db_1/bin/clscfg.bin: error while loading shared libraries: libcap.so.1: cannot open shared object file: No such file or directory
Failed to create keys in the OLR, rc = 32512, 32512
OLR configuration failed

 
Turns out there are a couple more RPMs we needed to load that the installer forgot to mention. Specifically they are:

• libcap-2.16-5.5.el6.i686.rpm
• compat-libcap1-1.10-1.i686.rpm
• compat-libcap1-1.10-1.x86_64.rpm

On CentOS 6.3 we can load all these RPMs and required dependencies with the following command:

rpm -ivh libcap-2.16-5.5.el6.i686.rpm \
libattr-2.4.44-7.el6.i686.rpm \
compat-libcap1-1.10-1.*.rpm

And we can find these on the install media, this example again from CentOS 6.3 shows them being loaded:

[root@localhost ~]# cd "/media/CentOS_6.3_Final/Packages/"

[root@localhost Packages]# rpm -ivh libcap-2.16-5.5.el6.i686.rpm \
> libattr-2.4.44-7.el6.i686.rpm \
> compat-libcap1-1.10-1.*.rpm
warning: libcap-2.16-5.5.el6.i686.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
Preparing...                ########################################### [100%]
   1:libattr                ########################################### [ 25%]
   2:compat-libcap1         ########################################### [ 50%]
   3:libcap                 ########################################### [ 75%]
   4:compat-libcap1         ########################################### [100%]
[root@localhost Packages]#

 
If you encounter this problem during the install, you will need to use the rootcrs.pl script to de-configure the Grid before you can run root.sh again.

The rootcrs.pl script is found in the Grid home under crs/install

[root@localhost install]# pwd
/u01/app/oracle/product/11.2.0/db_1/crs/install

[root@localhost install]# ./rootcrs.pl -deconfig -force -verbose
2012-11-05 18:52:33: Parsing the host name
2012-11-05 18:52:33: Checking for super user privileges
2012-11-05 18:52:33: User has super user privileges
Using configuration parameter file: ./crsconfig_params

 
Once the script completes you can execute root.sh again