Security setting - Failed to start services on hadoop, such as name node.

Note: this is the one of the reasons why the services of hadoop fail to start.

1. The security setting of linux system might the reason why your services of hadoop fail to start while using, for example, CDH.
2. Some time, you have to apply "chmod" to commands, because of your security setting of linux system.
3. for instance,

chmod 755 df netstat dmesg find ps c++ g++ last make top w who whoami x86_64-redhat-linux-* ...

4. And, the commands you have to change are depends on your security setting.
5. As a example, remember to delete name node directory before restart name node. Otherwise it will keep failing.