hadoop 部署

创建 hadoop 用户

root 用户身份登陆

useradd -m hadoop -s /bin/bash 
passwd hadoop
echo "hadoop  ALL=(ALL) NOPASSWD: ALL" >/etc/sudoers.d/hadoop 

配置 ssh 无密码登陆

hadoop 用户身份登陆

ssh-keygen
ssh-copy-id localhost

安装Java环境

sudo yum install java-1.7.0-openjdk java-1.7.0-openjdk-devel
sudo sh -c "echo export JAVA_HOME=/usr/lib/jvm/java-1.7.0 >> /etc/profile"
. /etc/profile
java -version

安装 hadoop2

tar -zxvf hadoop-2.8.1.tar.gz
sudo mv hadoop-2.8.1 /usr/local/hadoop
sudo chown -R hadoop:hadoop /usr/local/hadoop/
cd /usr/local/hadoop
./bin/hadoop version

Hadoop单机配置(非分布式)

cd /usr/local/hadoop
mkdir ./input
cp ./etc/hadoop/*.xml ./input   # 将配置文件作为输入文件
./bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-*.jar grep ./input ./output 'dfs[a-z.]+'
cat ./output/*          # 查看运行结果

启动失败时处理方法

若出现提示 “INFO metrics.MetricsUtil: Unable to obtain hostName java.net.UnknowHostException”，这需要执行如下命令修改 hosts 文件，为你的主机名增加IP映射：

sudo sh -c "echo 127.0.0.1 $HOSTNAME >> /etc/hosts"