先安装elasticsearch
1、确保jdk已经安装，这里省略
2、参考网址 https://www.elastic.co/guide/en/elasticsearch/reference/6.0/deb.html 可知安装方法有多种，我选择的是以下方法
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.5.0-linux-x86_64.tar.gz
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.5.0-linux-x86_64.tar.gz.sha512
shasum -a 512 -c elasticsearch-7.5.0-linux-x86_64.tar.gz.sha512
tar -xzf elasticsearch-7.5.0-linux-x86_64.tar.gz
cd elasticsearch-7.5.0/ 先进入到除了root以外的目录，找一个你喜欢的目录（一般是放软件安装包的），按照这个步骤一步步的来安装，第三步的时候我遇到了 -bash: shasum: command not found 这个问题，通过执行 yum install perl-Digest-SHA 解决。
安装成功之后，启动es，进到es的安装目录，执行 ./bin/elasticsearch，报错：
future versions of Elasticsearch will require Java 11; your Java version from [/usr/local/jdk1.8.0_171/jre] does not meet this requirement
Exception in thread "main" java.lang.RuntimeException: starting java failed with [1]
output:
#
# There is insufficient memory for the Java Runtime Environment to continue.
# Native memory allocation (mmap) failed to map 986513408 bytes for committing reserved memory.
# An error report file with more information is saved as:
# logs/hs_err_pid21335.log
error:
Java HotSpot(TM) 64-Bit Server VM warning: INFO: os::commit_memory(0x00000000c5330000, 986513408, 0) failed; error='Cannot allocate memory' (errno=12)
at org.elasticsearch.tools.launchers.JvmErgonomics.flagsFinal(JvmErgonomics.java:118)
at org.elasticsearch.tools.launchers.JvmErgonomics.finalJvmOptions(JvmErgonomics.java:86)
at org.elasticsearch.tools.launchers.JvmErgonomics.choose(JvmErgonomics.java:59)
at org.elasticsearch.tools.launchers.JvmOptionsParser.main(JvmOptionsParser.java:92)无法分配内存，cat conf/jvm.options 里看到的 -Xms1g -Xmx1g，我把他们都改为256m，然后再启动，换了个报错信息：
future versions of Elasticsearch will require Java 11; your Java version from [/usr/local/jdk1.8.0_171/jre] does not meet this requirement
[2019-12-06T11:07:54,035][WARN ][o.e.b.ElasticsearchUncaughtExceptionHandler] [iZuf62rnwcgp54evv9uoo0Z] uncaught exception in thread [main]
org.elasticsearch.bootstrap.StartupException: java.lang.RuntimeException: can not run elasticsearch as root
at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:163) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.bootstrap.Elasticsearch.execute(Elasticsearch.java:150) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.cli.EnvironmentAwareCommand.execute(EnvironmentAwareCommand.java:86) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.cli.Command.mainWithoutErrorHandling(Command.java:125) ~[elasticsearch-cli-7.5.0.jar:7.5.0]
at org.elasticsearch.cli.Command.main(Command.java:90) ~[elasticsearch-cli-7.5.0.jar:7.5.0]
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:115) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:92) ~[elasticsearch-7.5.0.jar:7.5.0]
Caused by: java.lang.RuntimeException: can not run elasticsearch as root
at org.elasticsearch.bootstrap.Bootstrap.initializeNatives(Bootstrap.java:105) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:172) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:349) ~[elasticsearch-7.5.0.jar:7.5.0]
at org.elasticsearch.bootstrap.Elasticsearch.init(Elasticsearch.java:159) ~[elasticsearch-7.5.0.jar:7.5.0]
... 6 more这个是因为es默认不能用root用户启动，那下面我们去创建一个新的用户，和一个新的用户组
新增用户：
useradd elasticsearch
passwd elasticsearch
新增用户组：
groupadd elasticsearch
然后我 su elasticsearch 切换用户，然后去执行 ./bin/elasticsearch 报错：
Error: Could not find or load main class org.elasticsearch.tools.java_version_checker.JavaVersionChecker还记得我上面最开始的时候 第一个加红色的地方吗？一开始我是在root里安装es的，然后启动就会报这个错，所以我上面说不要在root目录里安装；然后我root用户执行
mv elasticsearch-7.5.0 /home/elasticsearch/ 命令把es包移到了home目录下，再启动es，报错：
future versions of Elasticsearch will require Java 11; your Java version from [/usr/local/jdk1.8.0_171/jre] does not meet this requirement
Exception in thread "main" java.nio.file.AccessDeniedException: /home/elasticsearch/elasticsearch-7.5.0/config/jvm.options
at sun.nio.fs.UnixException.translateToIOException(UnixException.java:84)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:102)
at sun.nio.fs.UnixException.rethrowAsIOException(UnixException.java:107)
at sun.nio.fs.UnixFileSystemProvider.newByteChannel(UnixFileSystemProvider.java:214)
at java.nio.file.Files.newByteChannel(Files.java:361)
at java.nio.file.Files.newByteChannel(Files.java:407)
at java.nio.file.spi.FileSystemProvider.newInputStream(FileSystemProvider.java:384)
at java.nio.file.Files.newInputStream(Files.java:152)
at org.elasticsearch.tools.launchers.JvmOptionsParser.main(JvmOptionsParser.java:62)这个是因为没权限，我上面新增用户和用户组之后，没有给用户授权，root用户执行
chown -R elasticsearch:elasticsearch /home/elasticsearch/ 即可，再次用elasticsearch用户启动es，成功。
新开一个窗口，执行curl http://localhost:9200/ 测试一下，出现下面json格式的信息，说明启动成功了
{
"name" : "iZuf62rnwcgp54evv9uoo0Z",
"cluster_name" : "elasticsearch",
"cluster_uuid" : "liYwoOgGQrirka3bSYrtiw",
"version" : {
"number" : "7.5.0",
"build_flavor" : "default",
"build_type" : "tar",
"build_hash" : "e9ccaed468e2fac2275a3761849cbee64b39519f",
"build_date" : "2019-11-26T01:06:52.518245Z",
"build_snapshot" : false,
"lucene_version" : "8.3.0",
"minimum_wire_compatibility_version" : "6.8.0",
"minimum_index_compatibility_version" : "6.0.0-beta1"
},
"tagline" : "You Know, for Search"
}至此，ES安装并启动成功，
启动：一般是后台 启动 ./elasticsearch -p /tmp/elasticsearch-pid -d
停止：jps | grep Elasticsearch 或者 cat /tmp/elasticsearch-pid && echo 找到PID，然后 kill -SIGTERM PID。
但是你有没有发现，这里只能用http://localhost:9200/访问，用服务器内网和外网都不能访问，如果我们想在浏览器里用外网访问该怎么办呢？
vim /home/elasticsearch/elasticsearch-7.5.0/config/elasticsearch.yml
Network模块里
network.host: 0.0.0.0
network.publish_host: 你自己的服务器外网地址重启，然后在阿里云安全组里打开9200这个端口，浏览器访问：http://外网:9200 即可访问
期间遇到的问题：可参考这个，我遇到的问题和这一样。。。
https://blog.csdn.net/weixin_38361347/article/details/93386009
然后还需要安装es的可视化插件es-head
git clone git://github.com/mobz/elasticsearch-head.git (没有git命令的话 yum install npm)
cd elasticsearch-head
npm install (没有npm命令的话 yum install npm)
npm run start 我是在npm install这一步出现错误的，错误信息如下：
可以看到应该是没有bzip2命令，安装 yum install bzip2
再次执行npm install，成功
然后启动：npm run start
启动成功，测试一下 curl http://localhost:9100
是成功的，然后我们把阿里云安全组里加入 9100端口，浏览器里使用外网访问：
外网可以访问，但是右边集群健康值:是未连接的，我们重启下 es，没有报错，但是浏览器里我还是连接不上我的es，
后来百度查到可能是 跨域的问题，我在elasticsearch.yml里新增下面两条命令
#allow origin
http.cors.enabled: true
http.cors.allow-origin: "*"重启es，打开浏览器ES控制面板，成功连接
至此为止，ES和ES的可视化插件就已经安装好了。
下篇文章继续安装Logstash
