Cannot run elasticesarch in ubuntu

Hello!
I followed the installation steps and when I try to run ./elasticsearch in my /bin/ path,this error came out:
log4j:ERROR setFile(null,true) call failed. java.io.FileNotFoundException: /opt/elasticsearch-2.3.2/logs/elasticsearch.log (Permission denied) at java.io.FileOutputStream.open(Native Method) at java.io.FileOutputStream.<init>(FileOutputStream.java:221) at java.io.FileOutputStream.<init>(FileOutputStream.java:142) at org.apache.log4j.FileAppender.setFile(FileAppender.java:294) at org.apache.log4j.FileAppender.activateOptions(FileAppender.java:165) at org.apache.log4j.DailyRollingFileAppender.activateOptions(DailyRollingFileAppender.java:223) at org.apache.log4j.config.PropertySetter.activate(PropertySetter.java:307) at org.apache.log4j.config.PropertySetter.setProperties(PropertySetter.java:172) at org.apache.log4j.config.PropertySetter.setProperties(PropertySetter.java:104) at org.apache.log4j.PropertyConfigurator.parseAppender(PropertyConfigurator.java:842) at org.apache.log4j.PropertyConfigurator.parseCategory(PropertyConfigurator.java:768) at org.apache.log4j.PropertyConfigurator.configureRootCategory(PropertyConfigurator.java:648) at org.apache.log4j.PropertyConfigurator.doConfigure(PropertyConfigurator.java:514) at org.apache.log4j.PropertyConfigurator.configure(PropertyConfigurator.java:440) at org.elasticsearch.common.logging.log4j.LogConfigurator.configure(LogConfigurator.java:128) at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:243) at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35) log4j:ERROR Either File or DatePattern options are not set for appender [file]. log4j:ERROR setFile(null,true) call failed. java.io.FileNotFoundException: /opt/elasticsearch-2.3.2/logs/elasticsearch_deprecation.log (Permission denied)

so I changed the user&user group of the elasticsearch.log to the same one with the elasticsearch file and make sure the elasticsearch.log file is access to the user,it still shows the same error.

Afterwards I change all the directory user to root,and I run the elasticsearch file as root,but another error came out ..

Exception in thread "main" java.lang.RuntimeException: don't run elasticsearch as root. at org.elasticsearch.bootstrap.Bootstrap.initializeNatives(Bootstrap.java:93) at org.elasticsearch.bootstrap.Bootstrap.setup(Bootstrap.java:144) at org.elasticsearch.bootstrap.Bootstrap.init(Bootstrap.java:270) at org.elasticsearch.bootstrap.Elasticsearch.main(Elasticsearch.java:35)

Anyone have any ideas?
Thanks a lot!

Like it says, never do this.

Given you are running on Ubuntu, why not install via the apt repo?

but..I try to run it as normal user,it shows the forward error

Your permissions are incorrect.

Again, use the repos, it'll manage everything for you.

okay I'll try it.Thanks!