[白开水]-maven的命令程序mvn脚本分析

    最近公司将svn迁移到git，而且使用maven管理代码仓库，所以小小的研究了一下，为自动化持续集成做知识准备，以下是分析了maven的命令程序mvn:

    总体感觉与tomcat的启动脚本startup大同小异

#!/bin/sh

# ----------------------------------------------------------------------------

# Licensed to the Apache Software Foundation (ASF) under one

# or more contributor license agreements.  See the NOTICE file

# distributed with this work for additional information

# regarding copyright ownership.  The ASF licenses this file

# to you under the Apache License, Version 2.0 (the

# "License"); you may not use this file except in compliance

# with the License.  You may obtain a copy of the License at

#

#    http://www.apache.org/licenses/LICENSE-2.0

#

# Unless required by applicable law or agreed to in writing,

# software distributed under the License is distributed on an

# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

# KIND, either express or implied.  See the License for the

# specific language governing permissions and limitations

# under the License.

# ----------------------------------------------------------------------------

# ----------------------------------------------------------------------------

# Maven2 Start Up Batch script

#

# Required ENV vars:

# ------------------

#   JAVA_HOME - location of a JDK home dir

#

# Optional ENV vars

# -----------------

#   M2_HOME - location of maven2's installed home dir

#   MAVEN_OPTS - parameters passed to the Java VM when running Maven

#     e.g. to debug Maven itself, use

#       set MAVEN_OPTS=-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=y,address=8000

#   MAVEN_SKIP_RC - flag to disable loading of mavenrc files

# ----------------------------------------------------------------------------

#如果系统里有多JDK版本，就可以在这里指定JAVA_HOME，这样即使JAVA_HOME环境变量不是这个，也可以从这里弥补

#M2_HOME 也可以在这里指定，maven会在家目录生成.m2目录

#MAVEN_OPTS 这个是设maven启动参数的，有兴趣的同学可以研究下

JAVA_HOME=/usr/java/jdk1.6.0_38

if [ -z "$MAVEN_SKIP_RC" ] ; then

  if [ -f /etc/mavenrc ] ; then

    . /etc/mavenrc

  fi

  if [ -f "$HOME/.mavenrc" ] ; then

    . "$HOME/.mavenrc"

  fi

fi

#如果环境变量MAVEN_SKIP_RC存在，则从下面3个外部文件找是否设置maven的环境变量，

#下面是系统环境检查，和tomcat的startup.sh一曲同工

# OS specific support.  $var _must_ be set to either true or false.

cygwin=false;

darwin=false;

mingw=false

case "`uname`" in

  CYGWIN*) cygwin=true ;;

  MINGW*) mingw=true;;

  Darwin*) darwin=true            

           #

           # Look for the Apple JDKs first to preserve the existing behaviour, and then look

           # for the new JDKs provided by Oracle.

           # 

           if [[ -z "$JAVA_HOME" && -L /System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK ]] ; then

             #

             # Apple JDKs

             #

             export JAVA_HOME=/System/Library/Frameworks/JavaVM.framework/Versions/CurrentJDK/Home

           fi

           

           if [[ -z "$JAVA_HOME" && -L /System/Library/Java/JavaVirtualMachines/CurrentJDK ]] ; then

             #

             # Apple JDKs

             #

             export JAVA_HOME=/System/Library/Java/JavaVirtualMachines/CurrentJDK/Contents/Home

           fi

             

           if [[ -z "$JAVA_HOME" && -L "/Library/Java/JavaVirtualMachines/CurrentJDK" ]] ; then

             #

             # Oracle JDKs

             #

             export JAVA_HOME=/Library/Java/JavaVirtualMachines/CurrentJDK/Contents/Home

           fi           

           ;;

esac

if [ -z "$JAVA_HOME" ] ; then

  if [ -r /etc/gentoo-release ] ; then

    JAVA_HOME=`java-config --jre-home`

  fi

fi

#此处貌似是为了照顾gentoo这个操作系统，特别加的，属于适应各操作系统方面的代码

if [ -z "$M2_HOME" ] ; then

  ## resolve links - $0 may be a link to maven's home

  PRG="$0"

#$0 ----当前shell名

  # need this for relative symlinks

  #test –h File    文件存在并且是一个符号链接（同-L） 

  while [ -h "$PRG" ] ; do

    ls=`ls -ld "$PRG"`

    link=`expr "$ls" : '.*-> \(.*\)$'`

    if expr "$link" : '/.*' > /dev/null; then

      PRG="$link"

    else

      PRG="`dirname "$PRG"`/$link"

    fi

  done

  #这个是排除软链接，找出真实的命令运行目录

  #如果有童鞋分析过tomcat的startup.sh脚本，就可以发现，上面的脚本基本雷同

  

  

  saveddir=`pwd`

  M2_HOME=`dirname "$PRG"`/..

  # make it fully qualified

  M2_HOME=`cd "$M2_HOME" && pwd`

  cd "$saveddir"

  # echo Using m2 at $M2_HOME

fi

#cd进入mvn的应用目录

# For Cygwin, ensure paths are in UNIX format before anything is touched

if $cygwin ; then

  [ -n "$M2_HOME" ] &&

    M2_HOME=`cygpath --unix "$M2_HOME"`

  [ -n "$JAVA_HOME" ] &&

    JAVA_HOME=`cygpath --unix "$JAVA_HOME"`

  [ -n "$CLASSPATH" ] &&

    CLASSPATH=`cygpath --path --unix "$CLASSPATH"`

fi

# For Migwn, ensure paths are in UNIX format before anything is touched

if $mingw ; then

  [ -n "$M2_HOME" ] &&

    M2_HOME="`(cd "$M2_HOME"; pwd)`"

  [ -n "$JAVA_HOME" ] &&

    JAVA_HOME="`(cd "$JAVA_HOME"; pwd)`"

  # TODO classpath?

fi

#上面一大串都是适应mingw和cygwin环境的，直接略过，下面才是干货

#test –z 字符串 字符串的长度为零  

#如果没有设置JAVA_HOME，程序就自己去找JAVA_HOME

if [ -z "$JAVA_HOME" ]; then

  javaExecutable="`which javac`"

  if [ -n "$javaExecutable" -a ! "`expr \"$javaExecutable\" : '\([^ ]*\)'`" = "no" ]; then

  #test –n 字符串的长度非零 

  #test 表达式1 –a 表达式2  两个表达式都为真 

    #link=`expr "$ls" : '.*-> \(.*\)$'` 模拟后： expr 'lrwxrwxrwx 1 root root 19 3月  17 10:12 ./bbb.sh -> /root/shell/test.sh' : '.*-> \(.*\)$'

    #很明确的发现是用expr来提取/root/shell/test.sh的内容

    #而这个循环就可以明确其目的，排除命令为链接，找出命令真正的目录，防止后面的命令出错 

    # readlink(1) is not available as standard on Solaris 10.

        #[^]            # 匹配不在指定组内的字符

        #上面的判读，主要是判断which javac，是否存在....

    readLink=`which readlink`

    if [ ! `expr "$readLink" : '\([^ ]*\)'` = "no" ]; then

      javaExecutable="`readlink -f \"$javaExecutable\"`"

      javaHome="`dirname \"$javaExecutable\"`"

      javaHome=`expr "$javaHome" : '\(.*\)/bin'`

      JAVA_HOME="$javaHome"

      export JAVA_HOME

    fi

  fi

fi

#如果没有设置JAVACMD，脚本就会在JAVA_HOME目录下去找

if [ -z "$JAVACMD" ] ; then

  if [ -n "$JAVA_HOME"  ] ; then

    if [ -x "$JAVA_HOME/jre/sh/java" ] ; then

      # IBM's JDK on AIX uses strange locations for the executables

      JAVACMD="$JAVA_HOME/jre/sh/java"

    else

      JAVACMD="$JAVA_HOME/bin/java"

    fi

  else

    JAVACMD="`which java`"

  fi

fi

#test –x File  文件存在并且可执行 

#javac命令用不了，那就报错了鸟~~~

if [ ! -x "$JAVACMD" ] ; then

  echo "Error: JAVA_HOME is not defined correctly."

  echo "  We cannot execute $JAVACMD"

  exit 1

fi

#没有定义JAVA_HOME，脚本有自己找不到，就会在这里报错

if [ -z "$JAVA_HOME" ] ; then

  echo "Warning: JAVA_HOME environment variable is not set."

fi

CLASSWORLDS_LAUNCHER=org.codehaus.plexus.classworlds.launcher.Launcher

# For Cygwin, switch paths to Windows format before running java

if $cygwin; then

  [ -n "$M2_HOME" ] &&

    M2_HOME=`cygpath --path --windows "$M2_HOME"`

  [ -n "$JAVA_HOME" ] &&

    JAVA_HOME=`cygpath --path --windows "$JAVA_HOME"`

  [ -n "$CLASSPATH" ] &&

    CLASSPATH=`cygpath --path --windows "$CLASSPATH"`

fi

#上面一堆代码的目的，就是为了下面一句代码提供变量.....

exec "$JAVACMD" \

  $MAVEN_OPTS \

  -classpath "${M2_HOME}"/boot/plexus-classworlds-*.jar \

  "-Dclassworlds.conf=${M2_HOME}/bin/m2.conf" \

  "-Dmaven.home=${M2_HOME}"  \

  ${CLASSWORLDS_LAUNCHER} "$@"

©著作权归作者所有：来自51CTO博客作者vekergu的原创作品，如需转载，请注明出处，否则将追究法律责任

maven mvn运维