windows http://blog.sina.com.cn/s/blog_61c006ea0100l1u6.html
linux http://blog.csdn.net/eifjgoergfgrgr/article/details/7556882
windows:
在XP上明明已经安装了JDK1.5并设置好了JAVA_HOME，可偏偏Tomcat在启动过程中找不到。
报错信息如下：Neither the JAVA_HOME nor the JRE_HOME environment variable is defined At least one of these environment variable is needed to run this program;提示找不到java_home各jre_home路径，何解？
原因不知道了，下面来看解决办法：
1、分析startup.bat启动脚本：发现其调用了catalina.bat,而catalina.bat调用了setclasspath.bat
2、在setclasspath.bat的头部定义了JAVA_HOME和JRE_HOME的值，那么在这里手动设置JAVA_HOME变量
rem ---------------------------------------------------------------------------
rem Set CLASSPATH and Java options
rem
rem $Id: setclasspath.bat 505241 2007-02-09 10:22:58Z jfclere $
rem ---------------------------------------------------------------------------
set JAVA_HOME=C:Program FilesJavajdk1.5.0_05
set JRE_HOME=C:Program FilesJavajre1.5.0_05
rem Make sure prerequisite environment variables are set
if not "%JAVA_HOME%" == "" goto gotJdkHome
if not "%JRE_HOME%" == "" goto gotJreHome
echo Neither the JAVA_HOME nor the JRE_HOME environment variable is defined
echo At least one of these environment variable is needed to run this program
goto exit
:gotJreHome
if not exist "%JRE_HOME%injava.exe" goto noJavaHome
if not exist "%JRE_HOME%injavaw.exe" goto noJavaHome
if not ""%1"" == ""debug"" goto okJavaHome
echo JAVA_HOME should point to a JDK in order to run in debug mode.
goto exit
:gotJdkHome
if not exist "%JAVA_HOME%injava.exe" goto noJavaHome
if not exist "%JAVA_HOME%injavaw.exe" goto noJavaHome
if not exist "%JAVA_HOME%injdb.exe" goto noJavaHome
if not exist "%JAVA_HOME%injavac.exe" goto noJavaHome
if not "%JRE_HOME%" == "" goto okJavaHome
set JRE_HOME=%JAVA_HOME%
goto okJavaHome
:noJavaHome
echo The JAVA_HOME environment variable is not defined correctly
echo This environment variable is needed to run this program
echo NB: JAVA_HOME should point to a JDK not a JRE
goto exit
:okJavaHome
if not "�SEDIR%" == "" goto gotBasedir
echo The BASEDIR environment variable is not defined
echo This environment variable is needed to run this program
goto exit
:gotBasedir
if exist "�SEDIR%insetclasspath.bat" goto okBasedir
echo The BASEDIR environment variable is not defined correctly
echo This environment variable is needed to run this program
goto exit
:okBasedir
rem Set the default -Djava.endorsed.dirs argument
set JAVA_ENDORSED_DIRS=�SEDIR%endorsed
rem Set standard CLASSPATH
rem Note that there are no quotes as we do not want to introduce random
rem quotes into the CLASSPATH
if not exist "%JAVA_HOME%in ools.jar" goto noJavac
set CLASSPATH=%JAVA_HOME%lib ools.jar
:noJavac
rem Set standard command for invoking Java.
rem Note that NT requires a window name argument when using start.
rem Also note the quoting as JAVA_HOME may contain spaces.
set _RUNJAVA="%JRE_HOME%injava"
set _RUNJAVAW="%JRE_HOME%injavaw"
set _RUNJDB="%JAVA_HOME%injdb"
set _RUNJAVAC="%JAVA_HOME%injavac"
goto end
:exit
exit /b 1
:end
3、重启tomcat，敲入http://localhost:8080验证，问题解决。
tomcat5需要jdk1.6做支撑，jdk1.5不能够。
linux
先看Tomcat的startup.bat，它调用了catalina.bat,而catalina.bat则调用了setclasspath.bat。只要在setclasspath.bat的开头声明环境变量，打开tomcat的bin目录下面的setclasspath.sh，添加红色部分，路径自己修改
#!/bin/sh
# -----------------------------------------------------------------------------
# Set CLASSPATH and Java options
#
# $Id: setclasspath.sh 467182 2006-10-23 23:47:06Z markt $
# -----------------------------------------------------------------------------
export JAVA_HOME=/usr/lib/jvm/java-6-sun
export JRE_HOME=/usr/lib/jvm/java-6-sun/jre
# First clear out the user classpath
CLASSPATH=
# Make sure prerequisite environment variables are set
if [ -z "$JAVA_HOME" -a -z "$JRE_HOME" ]; then
# Bugzilla 37284
if $darwin && [ -d "/System/Library/Frameworks/JavaVM.framework/Versions/1.5/Home" ]; then
export JAVA_HOME="/System/Library/Frameworks/JavaVM.framework/Versions/1.5/Home"
else
echo "Neither the JAVA_HOME nor the JRE_HOME environment variable is defined"
echo "At least one of these environment variable is needed to run this program"
exit 1
fi
fi
if [ -z "$JAVA_HOME" -a "$1" = "debug" ]; then
echo "JAVA_HOME should point to a JDK in order to run in debug mode."
exit 1
fi
if [ -z "$JRE_HOME" ]; then
JRE_HOME="$JAVA_HOME"
fi
# If we're running under jdb, we need a full jdk.
if [ "$1" = "debug" -o "$1" = "javac" ] ; then
if [ "$os400" = "true" ]; then
if [ ! -x "$JAVA_HOME"/bin/java -o ! -x "$JAVA_HOME"/bin/javac ]; then
echo "The JAVA_HOME environment variable is not defined correctly"
echo "This environment variable is needed to run this program"
echo "NB: JAVA_HOME should point to a JDK not a JRE"
exit 1
fi
else
if [ ! -x "$JAVA_HOME"/bin/java -o ! -x "$JAVA_HOME"/bin/jdb -o ! -x "$JAVA_HOME"/bin/javac ]; then
echo "The JAVA_HOME environment variable is not defined correctly"
echo "This environment variable is needed to run this program"
echo "NB: JAVA_HOME should point to a JDK not a JRE"
exit 1
fi
fi
fi
if [ -z "$BASEDIR" ]; then
echo "The BASEDIR environment variable is not defined"
echo "This environment variable is needed to run this program"
exit 1
fi
if [ ! -x "$BASEDIR"/bin/setclasspath.sh ]; then
if $os400; then
# -x will Only work on the os400 if the files are:
# 1. owned by the user
# 2. owned by the PRIMARY group of the user
# this will not work if the user belongs in secondary groups
eval
else
echo "The BASEDIR environment variable is not defined correctly"
echo "This environment variable is needed to run this program"
exit 1
fi
fi
# Set the default -Djava.endorsed.dirs argument
JAVA_ENDORSED_DIRS="$BASEDIR"/endorsed
# Set standard CLASSPATH
if [ "$1" = "debug" -o "$1" = "javac" ] ; then
CLASSPATH="$JAVA_HOME"/lib/tools.jar
fi
# OSX hack to CLASSPATH
JIKESPATH=
if [ `uname -s` = "Darwin" ]; then
OSXHACK="/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Classes"
if [ -d "$OSXHACK" ]; then
for i in "$OSXHACK"/*.jar; do
JIKESPATH="$JIKESPATH":"$i"
done
fi
fi
# Set standard commands for invoking Java.
_RUNJAVA="$JRE_HOME"/bin/java
if [ "$os400" != "true" ]; then
_RUNJDB="$JAVA_HOME"/bin/jdb
fi
_RUNJAVAC="$JAVA_HOME"/bin/javac