Install and uninstall JDK in Linux

From: http://www.cnblogs.com/hbycool/articles/1672010.html

Install JDK Linux Step 1. First download JDK (jdk-1_5_0_02-linux-i586.rpm) from the Internet, recommended sun official website www.sun.com, download and put in the/home directory, of course, other places also.

Go to the installation directory

 

# Cd/home

# Cp jdk-1_5_0_02-linux-i586.rpm/usr/local

# Cd/usr/local

 

 

Add executable permissions to all users

 

 

# Chmod + x jdk-1_5_0_02-linux-i586.rpm.bin

#./Jdk-1_5_0_02-linux-i586.rpm.bin

 

 

The file jdk-1_5_0_02-linux-i586.rpm is generated, and executable permissions are also added to all users

 

# Chmod + x jdk-1_5_0_02-linux-i586.rpm

 

 

Installer

 

# Rpm-IVH jdk-1_5_0_02-linux-i586.rpm

 

 

If the installation protocol is displayed, simply accept it.

 

 

 

Install JDK in Linux Step 2. Set environment variables.

 

# Vi/etc/profile

 

 

Method 1:

Add at the end

 

# Set Java environment

Java_home =/usr/Java/jdk-1_5_0_02

Classpath =.: $ java_home/lib. Tools. Jar

Path = $ java_home/bin: $ path

Export java_home classpath path

 

Method 2:

(Valid)

Export java_home =/usr/Java/jdk1.5.0 _ 10/

 
# Note: append the bin directory of the newly added JDK to the beginning of $ path. In this way, when multiple JDK versions are installed in the system, the program will first search for the JDK version at the beginning.
 
Export Path = $ java_home/bin: $ path
 
Export classpath =.: $ java_home/lib/tools. jar: $ java_home/lib/dt. jar: $ classpath
 
After saving/etc/profile, do not forget to execute the following command to make changes to environment variables take effect immediately.
 
Code:
 
Source/etc/profile
 
If an error is reported when you run the preceding command, check whether the text you added in/etc/profile is incorrect.
 
Finally, check whether the environment variable changes take effect:
 
Code:
 
Java-version

Save and exit.

To enable JDK to be used by all users, you can:

 

VI/etc/profile. d/Java. Sh

 

 

Enter the following content in the new java. Sh file:

 

# Set Java environment

Java_home =/usr/Java/jdk-1_5_0_02

Classpath =.: $ java_home/lib/tools. Jar

Path = $ java_home/bin: $ path

Export java_home classpath path

 

 

Save and exit, and then assign permissions to Java. sh:

 

Chmod 755/etc/profile. d/Java. Sh

 

So the best way is to modify the. bashrc file.

 

Code

[Root @ linuxserver RPM] # vi. bashrc
Set java_home =/usr/Java/j2sdk1.4.2 _ 06
Export java_home
Set Path = $ path: $ java_home/bin
Export path
Set classpath =.: $ java_home/lib/dt. jar: $ java_home/lib/tools. Jar
Export classpath

 

 

Usually, you prefer to use the Export command to directly set it in shell.

 

Code

[Root @ linuxserver RPM] # export java_home =/usr/Java/j2sdk1.4.2 _ 06
[Root @ linuxserver RPM] # export classpath =.: $ java_home/lib/dt. jar: $ java_home/lib/tools. Jar
[Root @ linuxserver RPM] # export Path = $ path: $ java_home/bin

 

Another way is

Sudo gedit/etc/environment
Write the following two lines in the Text Editor:

Classpath =.:/usr/Java/jdk-1_5_0_02/lib
Java_home =/usr/Java/jdk-1_5_0_02/

 

Install JDK in Linux Step 3. Use the echo command on the terminal to check the environment variable settings.

# Echo $ java_home

# Echo $ classpath

# Echo $ path

4. Check whether JDK is successfully installed.

# Java-version

If you see the JVM version and related information, the installation is successful!

 

Set the environment to OK to see if JDK works normally. Let's write a test file test. java.

 

[Root @ linuxserver RPM] # VI test. Java
Class test {
Public static void main (string [] ARGs)
{
System. Out. println ("Hello world! ");
}
}

 

 

Save and exit. Compile and execute the following command:

 

[Root @ linuxserver text] # javac test. Java
[Root @ linuxserver text] # Java Test
Hello world!

 

To allow a user to run Java commands, modify the bash initialization file.
For example, longware has the permission to run Java commands.

 

Code

[Root @ linuxserver root] # vi/home/longware/. bashrc
Set java_home =/usr/Java/j2sdk1.4.2 _ 06
Export java_home
Set Path = $ path: $ java_home/bin
Export path
Set classpath =.: $ java_home/lib/dt. jar: $ java_home/lib/tools. Jar
Export classpath

========================================================== ======================================

Uninstall JDK

 

Uninstall default:

Log on to the system as the root user and open a terminal input.

# Rpm-Qa | grep gcj
The displayed content contains the following two lines of information:
# Java-1.4.2-gcj-compat-1.4.2.0-27jpp
# Java-1.4.2-gcj-compat-devel-l.4.2.0-27jpp
Uninstall
# Rpm e java-1.4.2-gcj-compat-devel-l.4.2.0-27jpp

# Rpm e java-1.4.2-gcj-compat-l.4.2.0-27jpp

Run rpm-e to uninstall other self-installed JDK. <javaxxxxx>