Centos7中yum安装jdk及配置环境变量

Centos7中yum安装jdk及配置环境变量

系统版本

[root@localhost ~]# cat /etc/redhat-release
CentOS Linux release 7.4.1708 (Core)
#安装之前先查看一下有无系统自带jdk

rpm -qa |grep java

rpm -qa |grep jdk

rpm -qa |grep gcj
#如果有就使用批量卸载命令

rpm -qa | grep java | xargs rpm -e --nodeps

直接yum安装1.8.0版本openjdk

[root@localhost ~]# yum install java-1.8.0-openjdk* -y
查看版本

[root@localhost ~]# java -version
openjdk version “1.8.0_161”
OpenJDK Runtime Environment (build 1.8.0_161-b14)
OpenJDK 64-Bit Server VM (build 25.161-b14, mixed mode)
默认jre jdk 安装路径是/usr/lib/jvm 下面

JAVA_HOME指向一个含有java可执行程序的目录(一般是在 bin/java中,此目录为/bin/java的上级目录),用cd 命令进入到 jvm下唯一的一个目录中 java-1.8.0-openjdk-1.8.0.161-0.b14.el7_3.x86_64,发现其下目录为

/jar/bin/java.jre-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64 这个链接是指向 java-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/jre 这个文件夹，所以，可以直接用export命令将 JAVA_HOME 指向
jre-1.8.0-openjdk-1.8.0.121-0.b14.el7_4.x86_64这个链接.

#临时生效
[root@localhost ~]# export JAVA_HOME=/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.121-0.b13.el7_3.x86_64
#当前用户生效的配置

vim ~/.bashrc
#在文件底部加入下面一句
export JAVA_HOME=/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64
#如果使所有用户生效的配置

复制代码
vim /etc/profile
#set java environment

export JAVA_HOME=/usr/lib/jvm/java

export CLASSPATH=.:$JAV{A}_{H}OME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/jre/lib/rt.jar

export PATH=$PATH:$JAVA_HOME/bin
复制代码

#使得配置生效

. /etc/profile

#查看变量

复制代码
[root@localhost ~]# echo $JAVA_HOME
/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64

[root@localhost ~]# echo $CLASSPATH
.:/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/lib/dt.jar:/usr/lib/jvm/jre-1.8.0-openjdk-1.8.0.161-0.b14.el7_4.x86_64/lib/tools.jar

复制代码
javac 和java 命令都有输出设置提示就表示安装和环境配置成功了

案例如下：

[root@instanc]# yum -y list java

Loaded plugins: langpacks, versionlock

Error: No matching Packages to list

[root@instanc]# rpm -qa |grep java

[root@instanc]# rpm -qa |grep jdk

[root@instanc]# rpm -qa |grep gcj

[root@instanc]# yum install java-1.8.0-openjdk* -y

--------中间有安装过程，最后complete

Complete!

[root@instance-ozyu8y37 ~]# java -version

openjdk version “1.8.0_191”

OpenJDK Runtime Environment (build 1.8.0_191-b12)

OpenJDK 64-Bit Server VM (build 25.191-b12, mixed mode)

[root@instance-ozyu8y37 ~]# cd /usr

[root@instance-ozyu8y37 usr]# ls

bin etc games include lib lib64 libexec local sbin share src tmp

[root@instance-ozyu8y37 usr]# cd lib

[root@instance-ozyu8y37 lib]# cd jvm

[root@instance-ozyu8y37 jvm]# ls

java

java-1.8.0

java-1.8.0-openjdk

java-1.8.0-openjdk-1.8.0.191.b12-0.el7_5.x86_64

java-1.8.0-openjdk-1.8.0.191.b12-0.el7_5.x86_64-debug

java-openjdk

jre

jre-1.8.0

jre-1.8.0-openjdk

jre-1.8.0-openjdk-1.8.0.191.b12-0.el7_5.x86_64

jre-1.8.0-openjdk-1.8.0.191.b12-0.el7_5.x86_64-debug

jre-openjdk

[root@instance-ozyu8y37 jvm]# vim /etc/profile # 配置java环境变量（所有用户）

System wide environment and startup programs, for login setup

Functions and aliases go in /etc/bashrc

It’s NOT a good idea to change this file unless you know what you

are doing. It’s much better to create a custom.sh shell script in

/etc/profile.d/ to make custom changes to your environment, as this

will prevent the need for merging in future updates.

pathmunge () {

case ":${PATH}:" in

    *:"$1":*)

        ;;

    *)

        if [ "$2" = "after" ] ; then

            PATH=$PATH:$1

        else

            PATH=$1:$PATH

        fi

esac

}

if [ -x /usr/bin/id ]; then

if [ -z "$EUID" ]; then

    # ksh workaround

    EUID=`/usr/bin/id -u`

    UID=`/usr/bin/id -ru`

fi

USER="`/usr/bin/id -un`"

LOGNAME=$USER

MAIL="/var/spool/mail/$USER"

fi

#set java environment

export JAVA_HOME=/usr/lib/jvm/java

export CLASSPATH=.:$JAV{A}_{H}OME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/jre/lib/rt.jar

export PATH=$PATH:$JAVA_HOME/bin

Path manipulation

if [ “$EUID” = “0” ]; then

pathmunge /usr/sbin

pathmunge /usr/local/sbin

else

pathmunge /usr/local/sbin after

pathmunge /usr/sbin after

fi

HOSTNAME=/usr/bin/hostname 2>/dev/null

HISTSIZE=1000

if [ “$HISTCONTROL” = “ignorespace” ] ; then

export HISTCONTROL=ignoreboth

else

export HISTCONTROL=ignoredups

fi

export PATH USER LOGNAME MAIL HOSTNAME HISTSIZE HISTCONTROL

By default, we want umask to get set. This sets it for login shell

Current threshold for system reserved uid/gids is 200

You could check uidgid reservation validity in

/usr/share/doc/setup-*/uidgid file

if [ $UID -gt 199 ] && [ “/usr/bin/id -gn” = “/usr/bin/id -un” ]; then

umask 002

else

umask 022

fi

for i in /etc/profile.d/*.sh /etc/profile.d/sh.local ; do

if [ -r "$i" ]; then

    if [ "${-#*i}" != "$-" ]; then 

        . "$i"

    else

        . "$i" >/dev/null

    fi

fi

done

unset i

unset -f pathmunge

setterm -blank 0 &> /dev/null

setterm -powersave off &> /dev/null

setterm -powerdown 0 &> /dev/null

ulimit -SHn 65535

[root@instance-ozyu8y37 jvm]# . /etc/profile #使配置生效

[root@instance-ozyu8y37 jvm]# java

Usage: java [-options] class [args…]

       (to execute a class)

or java [-options] -jar jarfile [args…]

       (to execute a jar file)

where options include:

-d32   use a 32-bit data model if available

-d64   use a 64-bit data model if available

-server   to select the "server" VM

              The default VM is server.



-cp 

-classpath 

              A : separated list of directories, JAR archives,

              and ZIP archives to search for class files.

-D=

              set a system property

-verbose:[class|gc|jni]

              enable verbose output

-version      print product version and exit

-version:

              Warning: this feature is deprecated and will be removed

              in a future release.

              require the specified version to run

-showversion  print product version and continue

-jre-restrict-search | -no-jre-restrict-search

              Warning: this feature is deprecated and will be removed

              in a future release.

              include/exclude user private JREs in the version search

-? -help      print this help message

-X            print help on non-standard options

-ea[:...|:]

-enableassertions[:...|:]

              enable assertions with specified granularity

-da[:...|:]

-disableassertions[:...|:]

              disable assertions with specified granularity

-esa | -enablesystemassertions

              enable system assertions

-dsa | -disablesystemassertions

              disable system assertions

-agentlib:[=]

              load native agent library , e.g. -agentlib:hprof

              see also, -agentlib:jdwp=help and -agentlib:hprof=help

-agentpath:[=]

              load native agent library by full pathname

-javaagent:[=]

              load Java programming language agent, see java.lang.instrument

-splash:

              show splash screen with specified image

See http://www.oracle.com/technetwork/java/javase/documentation/index.html for more details.

[root@instance-ozyu8y37 jvm]# javac

Usage: javac

where possible options include:

-g Generate all debugging info

-g:none Generate no debugging info

-g:{lines,vars,source} Generate only some debugging info

-nowarn Generate no warnings

-verbose Output messages about what the compiler is doing

-deprecation Output source locations where deprecated APIs are used

-classpath Specify where to find user class files and annotation processors

-cp Specify where to find user class files and annotation processors

-sourcepath Specify where to find input source files

-bootclasspath Override location of bootstrap class files

-extdirs Override location of installed extensions

-endorseddirs Override location of endorsed standards path

-proc:{none,only} Control whether annotation processing and/or compilation is done.

-processor [,,…] Names of the annotation processors to run; bypasses default discovery process

-processorpath Specify where to find annotation processors

-parameters Generate metadata for reflection on method parameters

-d Specify where to place generated class files

-s Specify where to place generated source files

-h Specify where to place generated native header files

-implicit:{none,class} Specify whether or not to generate class files for implicitly referenced files

-encoding Specify character encoding used by source files

-source Provide source compatibility with specified release

-target Generate class files for specific VM version

-profile Check that API used is available in the specified profile

-version Version information

-help Print a synopsis of standard options

-Akey[=value] Options to pass to annotation processors

-X Print a synopsis of nonstandard options

-J Pass directly to the runtime system

-Werror Terminate compilation if warnings occur

@ Read options and filenames from file

至此jdk安装成功