Hadoop安装
1.修改本机host，设置域名
0-1).vi /etc/hosts
192.168.128.138 yyl.hadoop
1). vi /etc/sysconfig/network
修改内容：
NETWORKING=yes
HOSTNAME=yyl.hadoop
2). hostname yyl.hadoop
2.SSH免密码登陆
yum -y install openssh-clients
su hadoop
ssh-keygen -t rsa -P ‘‘ -f ~/.ssh/id_rsa
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
chmod 600 ~/.ssh/authorized_keys
chmod 700 ~/.ssh/
