Installation of Apache Tomcat on Ubuntu

Steps.

• Download and install OpenJDK package for java ( Mandatory )
• Download Tomcat tarball from Official Tomcat Webpage
• Untar / Unzip the tarball.
• Make a directory specific for tomcat and it's relevant files
• Move tomcat files to specific tomcat directory
• Locate the startup.sh and shutdown.sh file in order to start/stop

Here we are about to download and install Tomcat 8 on CentOS 6.8

Install OpenJDK to fulfill java requirement.

## sudo apt-get instal openjdk*

Make a directory specific for Tomcat.

## sudo mkdir /opt/tomcat

Download Apache Tomcat from here official website 

Move the downloaded tarball apache-tomcat-x.xx.x.tar.gz into /opt/tomcat

## sudo mv  apache-tomcat-8.5.13.tar.gz /opt/tomcat/

Unzip the tarball

## tar -xvf apache-tomcat-8.5.13.tar.gz

After unzipping the tarball there would be something folder named as apache-tomcat-8.xx.xx

Toggle into unzipped directory

## cd /opt/tomcat/apache-tomcat-8.xx.xx/bin/

Look for file startup.sh and shutdown.sh

# Start tomcat using the startup script

## ./startup.sh

Stop the same from.

## ./shutdown.sh

 Once you toggle into unzipped tomcat parent directory below are the sub directories that has a significance value and it's is responsibility.
 Lets go through the Apache Tomcat Directory and know why they exists,

bin  ==> It contains all binary and script files for running tomcat

lib  ==> Contains shared library files used by tomcat

conf ==> Contains configuration files such as port, directories etc

logs ==> Contains various log files related to tomcat, ex -- catalina.out

temp ==> Conatins temp files associated with tomcat 

webapps ==> Important folder,application war files are dumped over here only

work ==> If application contain any jsp then jsp is translated and converted into servlet its stores here.

Tomcat looks for multiple environment variables to be defined in order to run, these are enlisted below.

CATALINA_HOME
CATALINA_BASE
CATALINA_TMPDIR
JRE_HOME/JAVA_HOME
CLASSPATH

The mandatory environment variable that are supposed to defined in order to run Tomcat.

CATALINA_HOME

1. This one is the most important Environment variable that needs to be defined in order to run multiple instances of tomcat within same host.
2. This directory defined must point to the main tomcat instance which contains all extracted binary data including the bin and lib directory
3. So based on CATALINA_HOME we will get lib and bin directory

CATALINA_BASE

Based on above variable, server uses conf, logs, webapps, work folder

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