2.x系列已经没有hadoop-core的jar包了，变成一个个散的了，分布在$HADOOP_HOME/share/hadoop下

vim /etc/profile
HADOOP_HOME=/home/finch/hadoop-2.7.

export CLASSPATH=.:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/lib/dt.jar:$HADOOP_HOME/share/hadoop/common/hadoop-common-2.7.5.jar:$HADOOP_HOME/share/hadoop/mapreduce/hadoop-mapreduce-client-core-2.7.5.jar:$HADOOP_HOME/share/hadoop/common/lib/commons-cli-1.2.jar