这几天终于把Hadoop折腾起来了，自从本科毕设做完就再没接触过，现在研究生论文又拾起来了，不过以前用的是Hadoop0.20.0，最新的稳定版本已经升到2.7.1了，对于我这停留在原先版本的人来说，改动还是挺大的。
先说一下刚搭建运行时报的错误：
WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable
Starting namenodes on [Java HotSpot(TM) Client VM warning: You have loaded library /hadoop/hadoop-2.7.1/lib/native/libhadoop.so.1.0.0 which might have disabled stack guard. The VM will try to fix the stack guard now.
It's highly recommended that you fix the library with 'execstack -c <libfile>', or link it with '-z noexecstack'.
SecondaryNameNode]
sed: -e expression #1, char 6: unknown option to `s'
-c: Unknown cipher type 'cd'
Client: ssh: Could not resolve hostname Client: Temporary failure in name resolution
have: ssh: Could not resolve hostname have: Temporary failure in name resolution
You: ssh: Could not resolve hostname You: Temporary failure in name resolution
Java: ssh: Could not resolve hostname Java: Temporary failure in name resolution
library: ssh: Could not resolve hostname library: Temporary failure in name resolution
loaded: ssh: Could not resolve hostname loaded: Temporary failure in name resolution
VM: ssh: Could not resolve hostname VM: Temporary failure in name resolution
might: ssh: Could not resolve hostname might: Temporary failure in name resolution
stack: ssh: Could not resolve hostname stack: Temporary failure in name resolution
have: ssh: Could not resolve hostname have: Temporary failure in name resolution
VM: ssh: Could not resolve hostname VM: Temporary failure in name resolution
fix: ssh: Could not resolve hostname fix: Temporary failure in name resolution
to: ssh: Could not resolve hostname to: Temporary failure in name resolution
the: ssh: Could not resolve hostname the: Temporary failure in name resolution
……解决方法：
在shell中输入 vi /etc/profile或者vi ~/.bash_profile。
写入环境变量
#换成你自己的hadoop安装目录，你懂的~
export HADOOP_HOME=/home/hadoop/labc/hadoop-2.7.1
export PATH=$PATH:$HADOOP_HOME/bin
export PATH=$PATH:$HADOOP_HOME/sbin
export HADOOP_MAPRED_HOME=$HADOOP_HOME
export HADOOP_COMMON_HOME=$HADOOP_HOME
export HADOOP_HDFS_HOME=$HADOOP_HOME
export YARN_HOME=$HADOOP_HOME
#最主要是两句，我就是敲错了
export HADOOP_COMMON_LIB_NATIVE_DIR=$HADOOP_HOME/lib/native
export HADOOP_OPTS="-Djava.library.path=$HADOOP_HOME/lib"
配置完记得重新编译，source /etc/profile或者source ~/.bash_profile。