Why attempting to generate ssh key during Hadoop installation you might get an error saying “ Saving the key failed : cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys”. If you follow the following few simple steps you will bypass that error.
Generate and output key to id_rsa
>ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa
Then authorize the key
>cat ~/.ssh/id_dsa.pub >> ~/.ssh/authorized_keys
Then check if you could be able too ssh to your localhost