Open JDK is generally installed on Linux. The difference between OpenJDK and JDK: http://www.cnblogs.com/sxdcgaq8080/p/7487369.html
Start the installation steps below:
-------------------------------------------------- ------------------------first step----------------------- ------------------------------------------------
The first step is to uninstall the OpenJDK and related java files that come with the system
① Type in the command window:
java -version
You can see the OpenJDK version information that comes with the system.
②Type in the command window:
rpm -qa | grep java
Command description:
rpm management suite
-qa use query mode, query all packages
grep finds matching strings in a file
java find files containing java strings
In the above file:
The following can be deleted
java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64 java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64 java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64 java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
noarch files can be deleted without deleting
python-javapackages-3.4.1-11.el7.noarch tzdata-java-2016g-2.el7.noarch javapackages-tools-3.4.1-11.el7.noarch
③ Type in the command window:
rpm -e --nodeps java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64
But there will be an error, because under the ordinary user sxd user, there is no permission to operate these files.
solve:
Type in the command window:
su root
Enter the root user, you can have permission to operate these files.
For the complete command to delete a file, type in the command window:
rpm -e --nodeps java-1.7.0-openjdk-1.7.0.111-2.6.7.8.el7.x86_64 rpm -e --nodeps java-1.8.0-openjdk-1.8.0.102-4.b14.el7.x86_64 rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.102-4.b14.el7.x86_64 rpm -e --nodeps java-1.7.0-openjdk-headless-1.7.0.111-2.6.7.8.el7.x86_64
Command introduction:
rpm management suite
-e delete the specified package
--nodeps don't verify package file dependencies
④Check whether it has been deleted successfully
Type in the command window:
java -version
The representative has been deleted successfully.
⑤ If they have not been deleted, use yum -y remove to delete them
-------------------------------------------------- ----------------------------Step 2------------------- -------------------------------------------------- --------
The second step is to download the latest stable JDK
[Note]: Under which user the JDK is installed is for which user
①The download address is
The latest version download address: http://www.oracle.com/technetwork/java/javase/downloads/index.html
Download address of historical version: http://www.oracle.com/technetwork/java/javase/archive-139210.html
② Paste the address into the browser address bar
Downloading through the browser will default to the download directory of the current logged-in user.
For example, the current logged-in user is root, then the download location is "/root/download/jdk-8u144-linux-x64.tar.gz".
slow download
The current user is the sxd user, so you can see that the downloaded JDK file is located in /home/sxd/download/jdk-8u144-linux-x64.tar.gz
③ After the download is complete, copy the JDK compressed package to /usr/local/src/ for backup
Type the command:
cp jdk-8u144-linux-x64.tar.gz /usr/local/src/
Command description:
cp copies files or directories
jdk-8u144-linux-x64.tar.gz filename
/user/local/src target directory to copy
Something went wrong:
When cp copies files, there is a problem of insufficient permissions, which explains why when the JDK compressed file is just viewed above, the file name is red.
Instructions for modifying file or directory permissions: http://www.cnblogs.com/sxdcgaq8080/p/7498906.html
④ Modify the permissions of the JDK compressed file, and then perform the copy operation
Type at the command line:
chmod 755 jdk-8u144-linux-x64.tar.gz
Then type:
ls -al
You can see the effect:
The file name has been displayed in green, and the beginning of the line can actually see that the permissions have been changed to: -rwxr-xr-x
Next, type:
Change the permission to 777, still can't cp operation
⑤Finally enter the root user and perform the copy operation
Type:
This is copied successfully.
-------------------------------------------------- ---------------------third step-------------------------- -------------------------------------------------- -
The third step is to decompress the JDK
①Copy the /home/sxd/download/jdk-8u144-linux-x64.tar.gz file to /usr/java
At the command line type:
cp jdk-8u144-linux-x64.tar.gz /usr/java
②Unzip the JDK compressed file in the java directory
Type in the command window:
tar -zxvf jdk-8u144-linux-x64.tar.gz
Command introduction:
tar backup file
-zxvf
-z Process backup files via gzip command
-x restore file from backup file
-v show the command execution process
-f specifies the backup file
jdk-8u144-linux-x64.tar.gz filename
The file decompression is complete.
③ Delete the JDK compressed package
Type at the command line:
rm -f jdk-8u144-linux-x64.tar.gz
Command Explanation:
rm delete a file or directory
-f Force deletion of file or directory
-------------------------------------------------- -----------------------------------the fourth step------------ -------------------------------------------------- --------------------------
The fourth step configures the JDK environment variables
①Edit global variables
Type at the command line:
vim /etc/profile
Command description:
vim text editor
/etc/profile global variable file
In the text editing state, the cursor goes to the last line of the file, and the keyboard is pressed:
i
Enter insert state:
Paste the following on the last line of text:
Note that JAVA_HOME=/usr/java/jdk1.8.0_144 is your own directory
#java environment
export JAVA_HOME=/usr/java/jdk1.8.0_144
export CLASSPATH=.:${JAVA_HOME}/jre/lib/rt.jar:${JAVA_HOME}/lib/dt.jar:${JAVA_HOME}/lib/tools.jar
export PATH=$PATH:${JAVA_HOME}/bin
[Note]: CentOS6 is JAVAHOME, CentOS7 is {JAVA_HOME}
keyboard:
ESC shift+q
keyboard:
qw!
write and force quit.
If it doesn't work, you can use the keyboard:
x
One meaning is to save and exit.
-------------------------------------------------- -----------------------the fifth step------------------------ -------------------------------------------------- -
The fifth step is to make the environment variables just set take effect and check whether the installation is successful
①Make the environment variable you just set take effect
Type:
source /etc/profile
source /etc/profile或 . /etc/profile
②Check whether the configuration is successful
Type:
java -version
But if there is an error after linux environment variable configuration..-bash: /usr/local/java/jdk1.7.0_55/bin/java: /lib/ld-linux.so.2: bad ELF interpreter
Run the command: yum install glibc.i686
However, if you run the java -version command directly, an error will be reported. You need to use the source /etc/profile again to make the file take effect, because it is found that this file has been opened during the installation process. If you run the java -version command at this moment, it will prompt that the installation is successful.
Just follow the prompts to confirm the installation,...try it
======================================================================================================= ===================================================== ===
Finally completed, the steps are very simple, but if you don't know the entry command, you can refer to:
http://www.cnblogs.com/sxdcgaq8080/p/7470796.html
Study all the commands one by one.