MAVEN's command program MVN script analysis

     the company recently migrated svn to git and used maven to manage the code warehouse, so a little bit of research has been done to prepare for automated continuous integration, and here's an analysis of MAVEN's command program mvn:      general feeling with Tomcat startup script startup is similar to #!/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&nBsp 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, you can specify java_home here, so that even if the JAVA_HOME environment variable is not this, can also be made up from here #m2_home  can also be specified here, MAVEN will be generated at home directory. M2 Directory #maven_opts  This is the MAVEN start parameter, interested students can study the next Java_home=/usr/java /jdk1.6.0_38if [ -z  "$MAVEN _skip_rc"  ] ; then  if [ -f  /etc/mavenrc ] ; then    . /etc/mavenrc  fi  if [ -f  "$HOME/. MAVENRC " ] ; then    . " $HOME/.MAVENRC "  fifi# if the environment variable Maven_ SKIP_RC exists, find out if MAVEN environment variables are set from the 3 external files below, #下面是系统环境检查, and Tomcat's startup.sh a # os specific support.    $var  _must_ be set to either true or false.cygwin=false; darwin=false;mingw=falsecase  "' uname '"  in  cygwin*)  cygwin=true ;;   mingw*)  mingw=true;;   darwin*)  darwin=true                        #            # look for the apple jdks first to preserve  the existing behaviour, and then look            # for the new jdks provided by oracle.            #             if [[ -z  "$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                        ;; esacif [ -z  "$JAVA _home"  ] ; then  if [ -r /etc/ Gentoo-release ] ; then    java_home= ' Java-config --jre-home '    fifi# here seems to be to take care of Gentoo this operating system, in particular, belongs to adapt to the operating system code if [ -z  "$M 2_home"  ] ; then   ## resolve links - $0 may be a link to maven ' s  home  prg= "$" #$0 ----Current shell name   # need this for relative symlinks  # test –h file     file exists and is a symbolic link (same-l)    while [ -h  "$ 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, find out the actual command run directory    #如果有童鞋分析过tomcat的startup. Sh script, you can see that the above script is basically identical       saveddir= ' pwd '   m2_home= ' dirname  "$PRG" '/'.   # make it fully qualified  m2_home= ' cd  "$M 2_home"  & & pwd '   cd  ' $saveddIR "  # echo Using m2 at  $M 2_HOMEFI#CD into the MVN application directory # for cygwin,  ensure paths are in UNIX format before anything is  touchedif  $cygwin  ; then  [ -n  "$M 2_home"  ] &&     m2_home= ' cygpath --unix  "$M 2_home"   [ -n  "$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 touchedif  $mingw  ; then  [ -n  "$M 2_ HOME " ] &&    m2_home=" ' (cd  "$M 2_home";  pwd) ' "  [  -n  "$JAVA _home"  ] &Amp;&    java_home= "' (cd " $JAVA _home ";  pwd) '"   # TODO  classpath?fi# above a large string are adapted to MinGW and Cygwin environment, directly skip, the following is dry #test –z  string   string length is zero    #如果没有设置JAVA_ HOME, the program on its own to find java_homeif [ -z  "$JAVA _home"  ]; then  javaexecutable= "' which  javac "  if [ -n " $javaExecutable " -a ! " ' expr \ "$ Javaexecutable\ " :  \ ([^ ]*\) '" " = " no " ]; then   #test  –n   Length of string not 0     #test   expression 1 –a  expression 2   Two expressions are true        #link = ' expr  ' $ls  :  '. *-> \ (. *\) $ '  : expr  after simulation ' lrwxrwxrwx 1  root root 19 3 Month   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 content      #而这个循环就可以明确其目的, excludingCommand for link, find command real directory, prevent subsequent command error      # readlink (1)  is not available  as standard on Solaris 10.        #[^]             #  matches characters not in the specified group           #上面的判读, mainly Judge Which javac, whether exists ....     readlink= ' which  Readlink '     if [ !  ' expr  ' $readLink  :  ' \ ([^ ]*\) '  =  "No"  ]; then      javaexecutable= "' readlink -f  \ "$javaExecutable \" "      javahome=" ' dirname \ "$javaExecutable \" ' "       javahome= ' expr  ' $javaHome  :  ' \ (. *\)/bin '        java_home= "$javaHome"       export JAVA_HOME     fi  fifi# ifWithout setting javacmd, the script will find if [ -z  "$JAVACMD" in the Java_home directory  ] ; 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 ' "  fifi#test –x File   file exists and executable   #javac命令用不了, then the bird ~~~if [  ! -x  "$JAVACMD"  ] ; then  echo  "Error: java_home is"  not defined correctly. "   echo  "  We cannot execute  $JAVACMD"   exit 1fi# no definition java_home, the script can not find it, will be here error if [ -z  "$JAVA _home"  ] ; then   echo  "Warning: java_home environment variable is not set." Ficlassworlds_launcher=org.codehaus.plexus.classworlds.launcher.launcher# for cygwin, switch  paths to Windows format before running javaif  $cygwin;  then   [ -n  "$M 2_home"  ] &&    m2_home= ' cygpath -- path --windows  "$M 2_home"   [ -n  "$JAVA _home"  ] &&     java_home= ' cygpath --path --windows  ' $JAVA _home "'   [ -n " $ CLASSPATH " ] &&    classpath= ' cygpath --path --windows " $ CLASSPATH "' fi# above a bunch of code to provide variables for the following code .....exec " $JAVACMD "    $MAVEN _opts    -classpath  "${m2_home}"/boot/plexus-classworlds-*.jar    "-dclassworlds.conf=${m2_home}/bin/m2.conf"     "-dmaven.home=${m2 _home} "    ${CLASSWORLDS_LAUNCHER} " [email protected] "

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MAVEN's command program MVN script analysis