Centos7中yum安装jdk及配置环境变量

[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

 

vim /etc/profile

 #set java environment  

 

export JAVA_HOME=/usr/lib/jvm/java

 

export CLASSPATH=.:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar:$JAVA_HOME/jre/lib/rt.jar

 

export PATH=$PATH:$JAVA_HOME/bin

 

 

#使得配置生效

 

. /etc/profile

 

 

#查看变量

 

[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

 

 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=.:$JAVA_HOME/lib/dt.jar:$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

 

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