正文之前
毕业答辩的时候，答辩老师说我的最大的问题就是没有和大数据扯上关系。所以后面就要想方设法扯点关系上去。被逼无奈的我。只能继续开始琢磨Hadoop了。以前其实我是想做的。。但是ubuntu上的Hadoop一度坑的我想死。。所以就没有继续了。。。现在只能重操旧业了。。
正文
1：安装Homebrew
这个是Mac上安装软件的神器。。。贼鸡儿好用。。。谁用谁知道！
安装Homebrew的方法，命令行键入下面的命令：
/usr/bin/ruby -e "$(curl -fsSLhttps://raw.githubusercontent.com/Homebrew/install/master/install)"
ps:homebrew常用shell命
查看brew的帮助
brew -help安装软件
brew install hadoop卸载软件
brew uninstall hadoop搜索软件
brew search hadoop查看已经安装的软件
brew list
*更新软件brew update更新某具体软件
brew upgrade hadoop
2:ssh登录本地
首先在系统里打开远程登录：
1:首先生成ssh公钥，终端命令代码如下
ssh-keygen -t rsa -P ""
cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
如果提示缺少文件的话，那就创建个文件好了。不过应该不会。。我是先创建然后再操作的。。
2:接下来进行测试登录本地是否成功，在 Terminal 里输入以下代码查看能不能免密 ssh 到 localhost：
ssh localhost
3:登录成功显示结果如下：
3:安装Hadoop
3.1 : 输入以下代码，自动安装hadoop:
brew install hadoop
ps：通过Homebrew安装软件后，软件目录一般位于/usr/local/Cellar,并软件目录里面带有版本号. 如图我的hadoop安装目录如下：
4:测试Hadoop是否安装成功
Hadoop有三种安装模式：单机模式，伪分布式模式，分布式模式 分布式模式需要在多台电脑上面测试，这里只测试 伪分布式模式
4.1:测试伪分布式模式
测试为分布模式前，需要修改相关的5个配置文件，把homebrew默认的单机模式修改成伪分布式模式
可以使用nano或者vim进行配置文件的修改，我这里使用sublime文本编辑器修改，方便省事儿。另外就是在sublime里面经常没法找到那些隐藏文件夹下的文件。所以这里我提供一个好办法，用命令行启动sublime！逼格满满还好用！
sublime 提供命令行的工具叫subs，路径在：
/Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl
使用ln命令
ln命令是做文件链接用的，不恰当的例子可以称之为建立快捷方式。
ln /Applications/Sublime\ Text.app/Contents/SharedSupport/bin/subl /usr/local/bin/subl
如上命令是将sublime提供的subl命令链接到usr/local/bin/subl 这个路径上来，usr/local/bin 这个文件夹是全局都可以访问到的命令所在的目录，都是我们自己下载安装的一些命令行工具链接所在地 比如npm、httpie等
搞完了之后，简单的这样就ok！
下面进行文件修改，修改路径为：
你按照你的来就好
修改core-site.xml（位置 etc/hadoop/），改参数如下：
<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="configuration.xsl"?><!-- Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. See accompanying LICENSE file. --><!-- Put site-specific property overrides in this file. --><configuration> <property> <name>hadoop.tmp.dir</name> <value>/usr/local/Cellar/hadoop/hdfs/tmp</value> <description>A base for other temporary directories</description> </property> <property> <name>fs.default.name</name> <value>hdfs://localhost:9000</value> </property></configuration>
.修改mapred-site.xml （位置 etc/hadoop/），改参数如下：
如果文件后缀是 .xml.example，改为 .xml。
<?xml version="1.0"?><?xml-stylesheet type="text/xsl" href="configuration.xsl"?><!-- Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. See accompanying LICENSE file. --><!-- Put site-specific property overrides in this file. --><configuration> <property> <name>mapred.job.tracker</name> <value>localhost:9010</value> </property> <property> <name>mapreduce.framework.name</name> <value>yarn</value> </property></configuration>
变量mapred.job.tracker 保存了JobTracker的位置，因为只有MapReduce组件需要知道这个位置，所以它出现在mapred-site.xml文件中。
修改hdfs-site.xml（位置 etc/hadoop/），改参数如下：
<?xml version="1.0" encoding="UTF-8"?><?xml-stylesheet type="text/xsl" href="configuration.xsl"?><!-- Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. See accompanying LICENSE file. --><!-- Put site-specific property overrides in this file. --><configuration> <property> <name>dfs.replication</name> <value>1</value> </property></configuration>
变量dfs.replication指定了每个HDFS数据库的复制次数。 通常为3, 由于我们只有一台主机和一个伪分布式模式的DataNode，将此值修改为1。
修改yarn-site.xml（位置 etc/hadoop/），改参数如下：
<?xml version="1.0"?><!-- Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. See accompanying LICENSE file. --><configuration><!-- Site specific YARN configuration properties --> <property> <name>yarn.nodemanager.aux-services</name> <value>mapreduce_shuffle</value> </property></configuration>
修改hadoop-env.sh（位置 etc/hadoop/），改参数如下：然后开启hadoop-env.sh里的注释
#
# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements. See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership. The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License. You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# Set Hadoop-specific environment variables here.
##
## THIS FILE ACTS AS THE MASTER FILE FOR ALL HADOOP PROJECTS.
## SETTINGS HERE WILL BE READ BY ALL HADOOP COMMANDS. THEREFORE,
## ONE CAN USE THIS FILE TO SET YARN, HDFS, AND MAPREDUCE
## CONFIGURATION OPTIONS INSTEAD OF xxx-env.sh.
##
## Precedence rules:
##
## {yarn-env.sh|hdfs-env.sh} > hadoop-env.sh > hard-coded defaults
##
## {YARN_xyz|HDFS_xyz} > HADOOP_xyz > hard-coded defaults
##
# Many of the options here are built from the perspective that users
# may want to provide OVERWRITING values on the command line.
# For example:
#
# JAVA_HOME=/usr/java/testing hdfs dfs -ls
#
# Therefore, the vast majority (BUT NOT ALL!) of these defaults
# are configured for substitution and not append. If append
# is preferable, modify this file accordingly.
###
# Generic settings for HADOOP
###
# Technically, the only required environment variable is JAVA_HOME.
# All others are optional. However, the defaults are probably not
# preferred. Many sites configure these options outside of Hadoop,
# such as in /etc/profile.d
# The java implementation to use. By default, this environment
# variable is REQUIRED on ALL platforms except OS X!
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_172.jdk/Contents/Home
# Location of Hadoop. By default, Hadoop will attempt to determine
# this location based upon its execution path.
# export HADOOP_HOME=
# Location of Hadoop's configuration information. i.e., where this
# file is living. If this is not defined, Hadoop will attempt to
# locate it based upon its execution path.
#
# NOTE: It is recommend that this variable not be set here but in
# /etc/profile.d or equivalent. Some options (such as
# --config) may react strangely otherwise.
#
# export HADOOP_CONF_DIR=${HADOOP_HOME}/etc/hadoop
# The maximum amount of heap to use (Java -Xmx). If no unit
# is provided, it will be converted to MB. Daemons will
# prefer any Xmx setting in their respective _OPT variable.
# There is no default; the JVM will autoscale based upon machine
# memory size.
# export HADOOP_HEAPSIZE_MAX=
# The minimum amount of heap to use (Java -Xms). If no unit
# is provided, it will be converted to MB. Daemons will
# prefer any Xms setting in their respective _OPT variable.
# There is no default; the JVM will autoscale based upon machine
# memory size.
# export HADOOP_HEAPSIZE_MIN=
# Enable extra debugging of Hadoop's JAAS binding, used to set up
# Kerberos security.
# export HADOOP_JAAS_DEBUG=true
# Extra Java runtime options for all Hadoop commands. We don't support
# IPv6 yet/still, so by default the preference is set to IPv4.
# export HADOOP_OPTS="-Djava.net.preferIPv4Stack=true"
# For Kerberos debugging, an extended option set logs more invormation
export HADOOP_OPTS="-Djava.net.preferIPv4Stack=true -Dsun.security.krb5.debug=true -Dsun.security.spnego.debug"
# Some parts of the shell code may do special things dependent upon
# the operating system. We have to set this here. See the next
# section as to why....
export HADOOP_OS_TYPE=${HADOOP_OS_TYPE:-$(uname -s)}
# Under certain conditions, Java on OS X will throw SCDynamicStore errors
# in the system logs.
# See HADOOP-8719 for more information. If one needs Kerberos
# support on OS X, one will want to change/remove this extra bit.
case ${HADOOP_OS_TYPE} in
Darwin*)
export HADOOP_OPTS="${HADOOP_OPTS} -Djava.security.krb5.realm= "
export HADOOP_OPTS="${HADOOP_OPTS} -Djava.security.krb5.kdc= "
export HADOOP_OPTS="${HADOOP_OPTS} -Djava.security.krb5.conf= "
;;
esac
# Extra Java runtime options for some Hadoop commands
# and clients (i.e., hdfs dfs -blah). These get appended to HADOOP_OPTS for
# such commands. In most cases, # this should be left empty and
# let users supply it on the command line.
# export HADOOP_CLIENT_OPTS=""
#
# A note about classpaths.
#
# By default, Apache Hadoop overrides Java's CLASSPATH
# environment variable. It is configured such
# that it sarts out blank with new entries added after passing
# a series of checks (file/dir exists, not already listed aka
# de-deduplication). During de-depulication, wildcards and/or
# directories are *NOT* expanded to keep it simple. Therefore,
# if the computed classpath has two specific mentions of
# awesome-methods-1.0.jar, only the first one added will be seen.
# If two directories are in the classpath that both contain
# awesome-methods-1.0.jar, then Java will pick up both versions.
# An additional, custom CLASSPATH. Site-wide configs should be
# handled via the shellprofile functionality, utilizing the
# hadoop_add_classpath function for greater control and much
# harder for apps/end-users to accidentally override.
# Similarly, end users should utilize ${HOME}/.hadooprc .
# This variable should ideally only be used as a short-cut,
# interactive way for temporary additions on the command line.
# export HADOOP_CLASSPATH="/some/cool/path/on/your/machine"
# Should HADOOP_CLASSPATH be first in the official CLASSPATH?
# export HADOOP_USER_CLASSPATH_FIRST="yes"
# If HADOOP_USE_CLIENT_CLASSLOADER is set, the classpath along
# with the main jar are handled by a separate isolated
# client classloader when 'hadoop jar', 'yarn jar', or 'mapred job'
# is utilized. If it is set, HADOOP_CLASSPATH and
# HADOOP_USER_CLASSPATH_FIRST are ignored.
# export HADOOP_USE_CLIENT_CLASSLOADER=true
# HADOOP_CLIENT_CLASSLOADER_SYSTEM_CLASSES overrides the default definition of
# system classes for the client classloader when HADOOP_USE_CLIENT_CLASSLOADER
# is enabled. Names ending in '.' (period) are treated as package names, and
# names starting with a '-' are treated as negative matches. For example,
# export HADOOP_CLIENT_CLASSLOADER_SYSTEM_CLASSES="-org.apache.hadoop.UserClass,java.,javax.,org.apache.hadoop."
# Enable optional, bundled Hadoop features
# This is a comma delimited list. It may NOT be overridden via .hadooprc
# Entries may be added/removed as needed.
# export HADOOP_OPTIONAL_TOOLS="hadoop-openstack,hadoop-aliyun,hadoop-azure,hadoop-azure-datalake,hadoop-aws,hadoop-kafka"
###
# Options for remote shell connectivity
###
# There are some optional components of hadoop that allow for
# command and control of remote hosts. For example,
# start-dfs.sh will attempt to bring up all NNs, DNS, etc.
# Options to pass to SSH when one of the "log into a host and
# start/stop daemons" scripts is executed
# export HADOOP_SSH_OPTS="-o BatchMode=yes -o StrictHostKeyChecking=no -o ConnectTimeout=10s"
# The built-in ssh handler will limit itself to 10 simultaneous connections.
# For pdsh users, this sets the fanout size ( -f )
# Change this to increase/decrease as necessary.
# export HADOOP_SSH_PARALLEL=10
# Filename which contains all of the hosts for any remote execution
# helper scripts # such as workers.sh, start-dfs.sh, etc.
# export HADOOP_WORKERS="${HADOOP_CONF_DIR}/workers"
###
# Options for all daemons
###
#
#
# Many options may also be specified as Java properties. It is
# very common, and in many cases, desirable, to hard-set these
# in daemon _OPTS variables. Where applicable, the appropriate
# Java property is also identified. Note that many are re-used
# or set differently in certain contexts (e.g., secure vs
# non-secure)
#
# Where (primarily) daemon log files are stored.
# ${HADOOP_HOME}/logs by default.
# Java property: hadoop.log.dir
# export HADOOP_LOG_DIR=${HADOOP_HOME}/logs
# A string representing this instance of hadoop. $USER by default.
# This is used in writing log and pid files, so keep that in mind!
# Java property: hadoop.id.str
# export HADOOP_IDENT_STRING=$USER
# How many seconds to pause after stopping a daemon
# export HADOOP_STOP_TIMEOUT=5
# Where pid files are stored. /tmp by default.
# export HADOOP_PID_DIR=/tmp
# Default log4j setting for interactive commands
# Java property: hadoop.root.logger
# export HADOOP_ROOT_LOGGER=INFO,console
# Default log4j setting for daemons spawned explicitly by
# --daemon option of hadoop, hdfs, mapred and yarn command.
# Java property: hadoop.root.logger
# export HADOOP_DAEMON_ROOT_LOGGER=INFO,RFA
# Default log level and output location for security-related messages.
# You will almost certainly want to change this on a per-daemon basis via
# the Java property (i.e., -Dhadoop.security.logger=foo). (Note that the
# defaults for the NN and 2NN override this by default.)
# Java property: hadoop.security.logger
# export HADOOP_SECURITY_LOGGER=INFO,NullAppender
# Default process priority level
# Note that sub-processes will also run at this level!
# export HADOOP_NICENESS=0
# Default name for the service level authorization file
# Java property: hadoop.policy.file
# export HADOOP_POLICYFILE="hadoop-policy.xml"
#
# NOTE: this is not used by default! <-----# You can define variables right here and then re-use them later on.# For example, it is common to use the same garbage collection settings# for all the daemons. So one could define:#
# export HADOOP_GC_SETTINGS="-verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps"#
# .. and then use it as per the b option under the namenode.###
# Secure/privileged execution###
#
# Out of the box, Hadoop uses jsvc from Apache Commons to launch daemons# on privileged ports. This functionality can be replaced by providing# custom functions. See hadoop-functions.sh for more information.#
# The jsvc implementation to use. Jsvc is required to run secure datanodes# that bind to privileged ports to provide authentication of data transfer# protocol. Jsvc is not required if SASL is configured for authentication of# data transfer protocol using non-privileged ports.# export JSVC_HOME=/usr/bin#
# This directory contains pids for secure and privileged processes.#export HADOOP_SECURE_PID_DIR=${HADOOP_PID_DIR}#
# This directory contains the logs for secure and privileged processes.# Java property: hadoop.log.dir# export HADOOP_SECURE_LOG=${HADOOP_LOG_DIR}#
# When running a secure daemon, the default value of HADOOP_IDENT_STRING# ends up being a bit bogus. Therefore, by default, the code will# replace HADOOP_IDENT_STRING with HADOOP_xx_SECURE_USER. If one wants# to keep HADOOP_IDENT_STRING untouched, then uncomment this line.# export HADOOP_SECURE_IDENT_PRESERVE="true"###
# NameNode specific parameters###
# Default log level and output location for file system related change# messages. For non-namenode daemons, the Java property must be set in# the appropriate _OPTS if one wants something other than INFO,NullAppender# Java property: hdfs.audit.logger# export HDFS_AUDIT_LOGGER=INFO,NullAppender# Specify the JVM options to be used when starting the NameNode.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# a) Set JMX options# export HDFS_NAMENODE_OPTS="-Dcom.sun.management.jmxremote=true -Dcom.sun.management.jmxremote.authenticate=false -Dcom.sun.management.jmxremote.ssl=false -Dcom.sun.management.jmxremote.port=1026"#
# b) Set garbage collection logs# export HDFS_NAMENODE_OPTS="${HADOOP_GC_SETTINGS} -Xloggc:${HADOOP_LOG_DIR}/gc-rm.log-$(date +'%Y%m%d%H%M')"#
# c) ... or set them directly# export HDFS_NAMENODE_OPTS="-verbose:gc -XX:+PrintGCDetails -XX:+PrintGCTimeStamps -XX:+PrintGCDateStamps -Xloggc:${HADOOP_LOG_DIR}/gc-rm.log-$(date +'%Y%m%d%H%M')"# this is the default:# export HDFS_NAMENODE_OPTS="-Dhadoop.security.logger=INFO,RFAS"###
# SecondaryNameNode specific parameters###
# Specify the JVM options to be used when starting the SecondaryNameNode.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# This is the default:# export HDFS_SECONDARYNAMENODE_OPTS="-Dhadoop.security.logger=INFO,RFAS"###
# DataNode specific parameters###
# Specify the JVM options to be used when starting the DataNode.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# This is the default:# export HDFS_DATANODE_OPTS="-Dhadoop.security.logger=ERROR,RFAS"# On secure datanodes, user to run the datanode as after dropping privileges.# This **MUST** be uncommented to enable secure HDFS if using privileged ports# to provide authentication of data transfer protocol. This **MUST NOT** be# defined if SASL is configured for authentication of data transfer protocol# using non-privileged ports.# This will replace the hadoop.id.str Java property in secure mode.# export HDFS_DATANODE_SECURE_USER=hdfs# Supplemental options for secure datanodes# By default, Hadoop uses jsvc which needs to know to launch a# server jvm.# export HDFS_DATANODE_SECURE_EXTRA_OPTS="-jvm server"###
# NFS3 Gateway specific parameters###
# Specify the JVM options to be used when starting the NFS3 Gateway.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_NFS3_OPTS=""# Specify the JVM options to be used when starting the Hadoop portmapper.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_PORTMAP_OPTS="-Xmx512m"# Supplemental options for priviliged gateways# By default, Hadoop uses jsvc which needs to know to launch a# server jvm.# export HDFS_NFS3_SECURE_EXTRA_OPTS="-jvm server"# On privileged gateways, user to run the gateway as after dropping privileges# This will replace the hadoop.id.str Java property in secure mode.# export HDFS_NFS3_SECURE_USER=nfsserver###
# ZKFailoverController specific parameters###
# Specify the JVM options to be used when starting the ZKFailoverController.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_ZKFC_OPTS=""###
# QuorumJournalNode specific parameters###
# Specify the JVM options to be used when starting the QuorumJournalNode.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_JOURNALNODE_OPTS=""###
# HDFS Balancer specific parameters###
# Specify the JVM options to be used when starting the HDFS Balancer.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_BALANCER_OPTS=""###
# HDFS Mover specific parameters###
# Specify the JVM options to be used when starting the HDFS Mover.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_MOVER_OPTS=""###
# Router-based HDFS Federation specific parameters# Specify the JVM options to be used when starting the RBF Routers.# These options will be appended to the options specified as HADOOP_OPTS# and therefore may override any similar flags set in HADOOP_OPTS#
# export HDFS_DFSROUTER_OPTS=""###
###
# Advanced Users Only!
###
#
# When building Hadoop, one can add the class paths to the commands# via this special env var:# export HADOOP_ENABLE_BUILD_PATHS="true"#
# To prevent accidents, shell commands be (superficially) locked# to only allow certain users to execute certain subcommands.# It uses the format of (command)_(subcommand)_USER.#
# For example, to limit who can execute the namenode command,
# export HDFS_NAMENODE_USER=hdfs这里记得要改掉Java的位置啊！！！
export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_172.jdk/Contents/Home
4.2：运行hadoop以及查看远端
第一步：进入文件夹（重要重要重要：后续所有操作一定要先进入当前hadoop文件夹）
cd /usr/local/Cellar/hadoop/3.0.0
第二步：格式化文件系统（是对namenode进行初始化）：
./bin/hdfs namenode -format
启动 NameNode 和 DataNode：
./sbin/start-dfs.sh
localhost:3.1.0 zhangzhaobo$ ./sbin/start-dfs.sh Starting namenodes on [localhost] Starting datanodes Starting secondary namenodes [localhost]2018-06-03 14:12:02,890 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable localhost:3.1.0 zhangzhaobo$
报错没关系。。随它去~
现在可以直接看到Overview 界面了：
让 HDFS 可以被用来执行 MapReduce jobs：
./bin/hdfs dfs -mkdir /user
./bin/hdfs dfs -mkdir /user/input
localhost:3.1.0 zhangzhaobo$ ./bin/hdfs dfs -mkdir /user2018-06-03 14:13:45,029 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable localhost:3.1.0 zhangzhaobo$ ./bin/hdfs dfs -mkdir /user/input2018-06-03 14:13:51,659 WARN util.NativeCodeLoader: Unable to load native-hadoop library for your platform... using builtin-java classes where applicable localhost:3.1.0 zhangzhaobo$
把input改成你想要命名的任意子文件夹名字即可，这里我选择命名input.
启动 ResourceManager 和 NodeManager：
./sbin/start-yarn.sh
localhost:3.1.0 zhangzhaobo$ ./sbin/start-yarn.sh Starting resourcemanager Starting nodemanagers localhost:3.1.0 zhangzhaobo$
现在你就可以看到All Applications 界面了：
上面大部分内容来自简书的两位优秀程序猿同学。。。通报下：
OK！下面进入深化拓展！！
首先就是可能因为安装Java的时候默认安装了一些版本。。所以会有一些奇形怪状的错误出来。。这里介绍下如何查看版本以及改变版本：
首先输入代码看看你把 Java 装到哪里了 ：
/usr/libexec/java_home
输入代码：
java -version
如果已经装了Java，你会看到类似酱紫结果：
localhost:3.1.0 zhangzhaobo$ java -version java version "1.8.0_172"Java(TM) SE Runtime Environment (build 1.8.0_172-b11) Java HotSpot(TM) 64-Bit Server VM (build 25.172-b11, mixed mode)
如果没有 ，用 Homebrew 安装了 Java8，老铁， 求你一定要加那个8.。不然9的话别怪我没警告你！
brew cask install java8
如果你本来就安装了Java9 其实也没关系，一起装了就好了！！你看我的：
一起装了之后，你只要告诉系统，我要的默认Java是哪个就ok了！这个时候输入如下命令：
subl ~/.bash_profile
然后开始编辑
基本上按照我这个就没啥错误了。。
export JAVA_HOME_9=/Library/Java/JavaVirtualMachines/jdk-9.0.1.jdk/Contents/Homeexport JAVA_HOME_8=/Library/Java/JavaVirtualMachines/jdk1.8.0_172.jdk/Contents/Homeexport JAVA_HOME=$JAVA_HOME_8alias jdk8='export JAVA_HOME=$JAVA_HOME_8'alias jdk9='export JAVA_HOME=$JAVA_HOME_9'
然后你再去那个地方改一下：
没错，就是这里！！
修改hadoop-env.sh（位置 etc/hadoop/），改参数如下：然后开启hadoop-env.sh里的注释，JAVA_HOME那儿改成后来的这个就ok了！然后你就发现啥事没有了。。不然你在8088那个网址肯定出错。。。
正文之后
溜了溜了。今晚健身完回去好好学习。。把ubuntu和Raspberry都搭个Hadoop，做个小集群。。。哇咔咔！毕设完成有望啊！！！
作者：HustWolf
链接：https://www.jianshu.com/p/a86ccd96b78a
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