elasticsearch：启动时指定jdk版本。

背景

我电脑环境的jdk是1.7，而需要的版本为1.8. 因此需要给elasticsearch指定jdk1.8（不需要将jdk1.8配置到环境变量）.

下载

1. jdk:点击下载jdk1.8
2. 解压 

tar -xvf xxx1.8.tar.gz

配置

修改elasticsearch启动脚本 

打开 elasticsearchHOME/bin/elasticsearch 编辑

[root]# vim bin/elasticsearch
添加以下代码
export JAVA_HOME=/home/hiekay/jdk1.8.0_181/      （此处配置的为刚下的1.8的配置目录）
export PATH=$JAVA_HOME/bin:$PATH

if [ -x "$JAVA_HOME/bin/java" ]; then
        JAVA="/home/yutao/jdk1.8.0_121/bin/java"
else
        JAVA=`which java`
fi

完整配置文件

#!/bin/bash

CONTROLLING STARTUP:

This script relies on a few environment variables to determine startup
behavior, those variables are:

ES_PATH_CONF -- Path to config directory
ES_JAVA_OPTS -- External Java Opts on top of the defaults set

Optionally, exact memory values can be set using the `ES_JAVA_OPTS`. Note that
the Xms and Xmx lines in the JVM options file must be commented out. Example
values are "512m", and "10g".

ES_JAVA_OPTS="-Xms8g -Xmx8g" ./bin/elasticsearch
#配置自己的jdk1.8
export JAVA_HOME=/home/hiekay/jdk1.8.0_181/
export PATH=$JAVA_HOME/bin:$PATH

source "`dirname "$0"`"/elasticsearch-env

ES_JVM_OPTIONS="$ES_PATH_CONF"/jvm.options
JVM_OPTIONS=`"$JAVA" -cp "$ES_CLASSPATH" org.elasticsearch.tools.launchers.JvmOptionsParser "$ES_JVM_OPTIONS"`
ES_JAVA_OPTS="${JVM_OPTIONS//\$\{ES_TMPDIR\}/$ES_TMPDIR} $ES_JAVA_OPTS"

#我添加的jdk判断
if [ -x "$JAVA_HOME/bin/java" ]; then
        JAVA="/home/hiekay/jdk1.8.0_181/bin/java"
else
        JAVA=`which java`
fi

cd "$ES_HOME"
manual parsing to find out, if process should be detached
if ! echo $* | grep -E '(^-d |-d$| -d |--daemonize$|--daemonize )' > /dev/null; then
  exec \
    "$JAVA" \
    $ES_JAVA_OPTS \
    -Des.path.home="$ES_HOME" \
    -Des.path.conf="$ES_PATH_CONF" \
    -Des.distribution.flavor="$ES_DISTRIBUTION_FLAVOR" \
    -Des.distribution.type="$ES_DISTRIBUTION_TYPE" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "$@"
else
  exec \
    "$JAVA" \
    $ES_JAVA_OPTS \
    -Des.path.home="$ES_HOME" \
    -Des.path.conf="$ES_PATH_CONF" \
    -Des.distribution.flavor="$ES_DISTRIBUTION_FLAVOR" \
    -Des.distribution.type="$ES_DISTRIBUTION_TYPE" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "$@" \
    <&- &
  retval=$?
  pid=$!
  [ $retval -eq 0 ] || exit $retval
  if [ ! -z "$ES_STARTUP_SLEEP_TIME" ]; then
    sleep $ES_STARTUP_SLEEP_TIME
  fi
  if ! ps -p $pid > /dev/null ; then
    exit 1
  fi
  exit 0
fi

exit $?