How Do I Set JAVA_HOME in Centos For Apache Tomcat?

Question

I have purchased a VPS with a top hosting company. I am new to Linux. Since I am not able to purchase a CPanel License, I need to manually install JDK, Tomcat, and MariaDB. All this through SSH using PUTTY.

There are tutorials which I have followed:

Setting JAVA_HOME & CLASSPATH in CentOS 6

How to Install Apache Tomcat 8.5 on CentOS 7.3

But since I am a newbie in Linux am only able to install JDK8.

Now I need to set JAVA_HOME in a bash file to remain permanent before I can continue with tomcat installation.

From PUTTY, I have login as root user with my password:

1. I checked the location of the Java "which java" : /usr/bin/java

2. To get the exact jdk name I used command "sudo update-alternatives --config java" >java-1.8.0-openjdk.x86_64 (/usr/lib/jvm/java-1.8.0-openjdk-1.8.0.144-0.b01.el7_4.x86_64/jre/bin/java)

3. I createed a new file through command "vim /etc/profile.d/java.sh" which gave the error below:

    E325: ATTENTION
    Found a swap file by the name "/etc/profile.d/.java.sh.swp"
              owned by: root   dated: Thu Oct 19 14:21:28 2017
             file name: /etc/profile.d/java.sh
              modified: YES
             user name: root   host name: rtp
            process ID: 31766
    While opening file "/etc/profile.d/java.sh"
    
    (1) Another program may be editing the same file.  If this is the case,
        be careful not to end up with two different instances of the same
        file when making changes.  Quit, or continue with caution.
    (2) An edit session for this file crashed.
        If this is the case, use ":recover" or "vim -r /etc/profile.d/java.sh"
        to recover the changes (see ":help recovery").
        If you did this already, delete the swap file "/etc/profile.d/.java.sh.swp"
        to avoid this message.
    
    Swap file "/etc/profile.d/.java.sh.swp" already exists!
    [O]pen Read-Only, (E)dit anyway, (R)ecover, (D)elete it, (Q)uit, (A)bort:

I pressed d to delete the existing one.

4. I copy this and pasted:

    export JAVA_HOME=/usr/bin/java/java-1.8.0-openjdk.x86_64 
    export PATH=$PATH:$JAVA_HOME/bin
    export CLASSPATH=$JAVA_HOME/jre/lib/ext:$JAVA_HOME/lib/tools.jar

And then I Press ENTER

The file is in insert mode so I press Esc :w java.sh to save and exit.

Then I closed the PUTTY session and started again to check if the JAVA_HOME has been set: "echo $JAVA_HOME"

No result!

I don't understand what to do again. I kept on repeating this for two days now. Please, any help?

Solution 1

Run below commands on shell prompt before adding it into java.sh:

export JAVA_HOME=/usr/bin/java/java-1.8.0-openjdk.x86_64 
export PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=$JAVA_HOME/jre/lib/ext:$JAVA_HOME/lib/tools.jar

Then run echo $JAVA_HOME

Solution 2

If your usage is covered by their licence, I strongly recommend to use Oracle's JDK RPM: when installed it provides much more sane directory layout than OpenJDK RPM package(s): you would be able to use "/usr/java/latest" as Java home. To have persistent environment variable, add export command to ~/.bashrc or ~/.bash_profile file (depending on how you perform remote login, add it to both if unsure): export JAVA_HOME=/usr/java/latest.

Comments

[Ityav]

i followed a giude as newbie i used this command:"yum -y install java-1.8.0-openjdk.x86_64 java-1.8.0-openjdk-devel.x86_64" i don't know how to get the Oracle's JDK or should i substitute?

[scrutari]

Normally you need one JDK. So if you choose to use one it's better to remove other (just to keep your system simpler). Oracle JDK RPM can be downloaded from Oracle's website.

[Ityav]

I will like to remove the open jdk and i used these command but it does not work:[root@rtp ~]# java -version openjdk version "1.8.0_144" OpenJDK Runtime Environment (build 1.8.0_144-b01) OpenJDK 64-Bit Server VM (build 25.144-b01, mixed mode) [root@rtp ~]# yum -y remove java* Loaded plugins: fastestmirror No Match for argument: java.sh No Packages marked for removal If i decide to install Oracle jdk8, will there any issue, Sir?

[scrutari]

Before running yum remove ... change you directory to some other directory where there is no file which would match pattern java* (like java.sh in your case) - YUM matches your pattern with local files first and only afterwards with RPM names.