How to Use yum to install and uninstall jdk and use yum to uninstall jdk
The installed CentOS comes with OpenJdk and uses the java-version command. The following information is displayed:
Java version "1.6.0"
OpenJDK Runtime Environment (build 1.6.0-b09)
OpenJDK 64-Bit Server VM (build 1.6.0-b09, mixed mode)
It is best to uninstall openjdk first and install the jdk of sun.
Check rpm-qa | grep java first
The following information is displayed:
Java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
Java-1.6.0-openjdk-1.6.0.0-1.7.b09.el5
Uninstall:
Rpm-e -- nodeps java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
Rpm-e -- nodeps java-1.6.0-openjdk-1.6.0.0-1.7.b09.el5
There are other commands
Rpm-qa | grep gcj
Rpm-qa | grep jdk
If openjdk source cannot be found, you can uninstall it like this.
Yum-y remove java java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
Yum-y remove java java-1.6.0-openjdk-1.6.0.0-1.7.b09.el5
Yes
1. view the Jdk installation path:
Whereis java
Which java (java execution path)
Echo $ JAVA_HOME
Echo $ PATH
Note: For windows, you can use:
Set java_home: view the JDK installation path
Java-version: view the JDK version.
2. Uninstall the old JDK version:
1. Determine the JDK version:
Rpm-qa | grep jdk
Rpm-qa | grep gcj
Possible results:
Libgcj-4.1.2-42.el5
Java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
2. Uninstall:
Yum-y remove java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
If this method does not work, you can use the following method to uninstall it:
1) uninstall the built-in jdk version:
View the built-in jdk:
# Rpm-qa | grep gcj
You may see the following similar information:
Libgcj-4.1.2-44.el5
Java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
Run the rpm-e -- nodeps command to delete the content found above:
# Rpm-e-nodeps java-1.4.2-gcj-compat-1.4.2.0-40jpp.115
2) uninstall the jkd version installed by rpm
View the installed jdk:
# Rpm-qa | grep jdk
You may see the following similar information:
Jdk-1.6.0_22-fcs
Uninstall:
# Rpm-e -- nodeps jdk-1.6.0_22-fcs
3) Find the _ uninst subdirectory of the jdk installation directory.
· Run the command./uninstall. sh on the shell terminal to uninstall jdk.
3. download the new JDK version
Official Address: http://www.oracle.com/technetwork/java/javase/downloads/index.htm
4. Install JDK (taking JDK 1.6 as an example)
1. jdk1.6 provides the following two types of self-extracting files:
1) jdk-6u22-linux-i586.bin
2) jdk-6u22-linux-i586-rpm.bin
2. I downloaded a jdk-6u22-linux-i586-rpm.bin.
3. Add executable permissions to all users
# Chmod + x jdk-6u22-linux-i586-rpm.bin
4. Run the following command to execute the file:
#./Jdk-6u22-linux-i586-rpm.bin
Some rpm packages will be decompressed after execution, with a jdk-6u22-linux-i586.rpm which is the main package, followed by installing this main package.
5. Switch to the root user, enter the jdk-6u22-linux-i586.rpm directory, execute the following command:
Rpm-ivh jdk-6u22-linux-i586.rpm
The installation software automatically installs JDK under the/usr/java/jdk-1.6.0_22-fcs directory
During linux installation, the following Fail is often encountered:
RPM shocould not be used directly install RPM packages, use Alien instead!
Then run the following command:
Rpm-ivh jdk-6u22-linux-i586.rpm -- nodeps -- force
5. Configure environment variables:
If you want to share the jdk environment variables, you can set them as follows.
(But it is recommended that you do not use this method unless other users use another JDK .)
Add the following to the/etc/profile file:
# Vi/etc/profile
Export JAVA_HOME =/usr/java/jdk-1.6.0_22-fcs
Export CLASSPATH = $ CLASSPATH: $ JAVA_HOME/lib: $ JAVA_HOME/jre/lib
Export PATH = $ JAVA_HOME/bin: $ JAVA_HOME/jre/bin: $ PATH: $ HOME/bin
Note: to change the file to take effect immediately, run # source/etc/profile. Otherwise, it will only take effect the next time you re-enter the user.
Remember to add $ classpath to the classpath path: otherwise, an error may be reported when the class file is interpreted and executed.
Of course, you can also use the more thorough method: reboot command to restart the machine.
Sometimes you may find that the environment variables configured in/etc/profile are invalid after the system is restarted or the SSH connection is used again.
1. The environment variable of a non-root user takes effect, but after switching to the root user, the javac and other commands fail.
2.The environment variables written to/etc/profile automatically take effect after the restart. Run the source command every time you open the terminal before restarting.
Appendix: how to install JDK of the tar type:
First decompress * .tar.gz
tar -xzvf *.tar.gz
Assume that the obtained folder is java
Move it to/usr/
sudo mv java /usr/local
Then set the environment variable:
sudo vim /etc/profile
Open a file
Enter at the end:
export JAVA_HOME=/usr/local/javaexport JRE_HOME=/usr/local/java/jre export CLASSPATH=.:$JAVA_HOME/lib:$JRE_HOME/lib:$CLASSPATHexport PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
In this step, add the installed jdk to the java menu.
update-alternatives --config java
Select the default jdk
java -version