環境

伺服器：centos6
作業系統：win7
工具：CRT
elasticsearch：6.0.0

場景

拿我公司舉例，我公司目前都是使用jdk1.7，並且線上已經有很多程式在跑啦！所以通過修改環境的方式，肯定是不行，而啟動elasticsearch.6.0，有需要jdk8

修改啟動指令碼

這種情況下，我們就需要在啟動elasticsearch時，就需要指定jdk版本。
即修改elasticsearch的啟動指令碼（elasticsearch_HOME/bin/elasticsearch）

[[email protected] elasticsearch-6.0.0]# vim bin/elasticsearch
 

# 新增以下程式碼
export JAVA_HOME=/home/yutao/jdk1.8.0_121/
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

這裡我也給我完整的檔案：

#!/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
# 我新增的 start
export JAVA_HOME=/home/yutao/jdk1.8.0_121/
export PATH=$JAVA_HOME/bin:$PATH
# 我新增的 end
source "`dirname "$0"`"/elasticsearch-env

parse_jvm_options() {
  if [ -f "$1" ]; then
    echo "`grep "^-" "$1" | tr '\n' ' '`"
  fi
}

ES_JVM_OPTIONS="$ES_PATH_CONF"/jvm.options

ES_JAVA_OPTS="`parse_jvm_options "$ES_JVM_OPTIONS"` $ES_JAVA_OPTS"

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

# 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="$ES_PATH_CONF" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "[email protected]"
else
  exec \
    "$JAVA" \
    $ES_JAVA_OPTS \
    -Des.path.home="$ES_HOME" \
    -Des.path.conf="$ES_PATH_CONF" \
    -cp "$ES_CLASSPATH" \
    org.elasticsearch.bootstrap.Elasticsearch \
    "[email protected]" \
    <&- &
  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 $?

這樣就修改完畢；

啟動時，不要用root使用者，被官方禁止啦！會報錯的！

還有我發現，有時修改明明對了，啟動時，還是報：

[[email protected] elasticsearch-6.0.0]# bin/elasticsearch
the minimum required Java version is 8; your Java version from [/usr/java/jdk1.7.0_51/jre] does not meet this requirement

有時又正常啦，不明白！

參考地址：