Hadoop 2.2.0启动脚本——etc/hadoop/hadoop-env.sh

1. export JAVA_HOME

2. 设置HADOOP_CONF_DIR，默认etc/hadoop

3. 设置HADOOP_CLASSPATH为contrib/capacity-scheduler/*.jar，即将所有jar包加入HADOOP_CLASSPATH

4. 设置HADOOP_OPTS，-Djava.net.preferIPv4Stack=true

5. 设置其他环境变量

export HADOOP_NAMENODE_OPTS="-Dhadoop.security.logger=${HADOOP_SECURITY_LOGGER:-INFO,RFAS} -Dhdfs.audit.logger=${HDFS_AUDIT_LOGGER:-INFO,NullAppender} $HADOOP_NAMENODE_OPTS"

export HADOOP_DATANODE_OPTS="-Dhadoop.security.logger=ERROR,RFAS $HADOOP_DATANODE_OPTS"

export HADOOP_SECONDARYNAMENODE_OPTS="-Dhadoop.security.logger=${HADOOP_SECURITY_LOGGER:-INFO,RFAS} -Dhdfs.audit.logger=${HDFS_AUDIT_LOGGER:-INFO,NullAppender} $HADOOP_SECONDARYNAMENODE_OPTS" 

export HADOOP_CLIENT_OPTS="-Xmx512m $HADOOP_CLIENT_OPTS" 

export HADOOP_SECURE_DN_USER=${HADOOP_SECURE_DN_USER} 

export HADOOP_SECURE_DN_LOG_DIR=${HADOOP_LOG_DIR}/${HADOOP_HDFS_USER} 

export HADOOP_PID_DIR=${HADOOP_PID_DIR}  

export HADOOP_SECURE_DN_PID_DIR=${HADOOP_PID_DIR}

export HADOOP_IDENT_STRING=$USER