//startup.sh指令碼會exec catalina.sh start
//整個catalina.sh就是判斷系統環境，確定java 後面的正確的啟動引數classpath catalinahome等等，然後啟動

判斷系統
cygwin=false
darwin=false
os400=false
hpux=false
case "`uname`" in
CYGWIN*) cygwin=true;;
Darwin*) darwin=true;;
OS400*) os400=true;;
HP-UX*) hpux=true;;
esac

找到tomcat的真實路徑，判斷是否軟連線
PRG="$0
 
"

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

# Get standard environment variables
PRGDIR=`dirname "$PRG"`

設定CATALINA_HOME，CATALINA_BASE
[ -z "$CATALINA_HOME
 
" ] && CATALINA_HOME=`cd "$PRGDIR/.." >/dev/null; pwd`

# Copy CATALINA_BASE from CATALINA_HOME if not already set
[ -z "$CATALINA_BASE" ] && CATALINA_BASE="$CATALINA_HOME"

置空CLASSPATH
CLASSPATH=

如果可讀載入setenv.sh，可以自己寫setenv.sh，定義環境變數
if [ -r "$CATALINA_BASE/bin/setenv.sh" ]; then
  . "$CATALINA_BASE
 
/bin/setenv.sh"
elif [ -r "$CATALINA_HOME/bin/setenv.sh" ]; then
  . "$CATALINA_HOME/bin/setenv.sh"
fi

Cygwin環境的處理
if $cygwin; then
  [ -n "$JAVA_HOME" ] && JAVA_HOME=`cygpath --unix "$JAVA_HOME"`
  [ -n "$JRE_HOME" ] && JRE_HOME=`cygpath --unix "$JRE_HOME"`
  [ -n "$CATALINA_HOME" ] && CATALINA_HOME=`cygpath --unix "$CATALINA_HOME"`
  [ -n "$CATALINA_BASE" ] && CATALINA_BASE=`cygpath --unix "$CATALINA_BASE"`
  [ -n "$CLASSPATH" ] && CLASSPATH=`cygpath --path --unix "$CLASSPATH"`
fi

變數路徑冒號判斷CATALINA_HOME，CATALINA_BASE
case $CATALINA_HOME in
  *:*) echo "Using CATALINA_HOME:   $CATALINA_HOME";
       echo "Unable to start as CATALINA_HOME contains a colon (:) character";
       exit 1;
esac
case $CATALINA_BASE in
  *:*) echo "Using CATALINA_BASE:   $CATALINA_BASE";
       echo "Unable to start as CATALINA_BASE contains a colon (:) character";
       exit 1;
esac

OS400系統處理
if $os400; then
  # Set job priority to standard for interactive (interactive - 6) by using
  # the interactive priority - 6, the helper threads that respond to requests
  # will be running at the same priority as interactive jobs.
  COMMAND='chgjob job('$JOBNAME') runpty(6)'
  system $COMMAND

  # Enable multi threading
  export QIBM_MULTI_THREADED=Y
fi

設定java變數 載入執行bin/setclasspath.sh (若果沒有設定JAVA_HOME，
會執行，JRE_HOME是根據JAVA_HOME設定，如果執行在jdb debug模式，
判斷JAVA_HOME是不是jdk的，有沒有javac)
還會設定變數_RUNJAVA="$JRE_HOME"/bin/java  _RUNJDB="$JAVA_HOME"/bin/jdb

if $os400; then
  # -r will Only work on the os400 if the files are:
  # 1. owned by the user
  # 2. owned by the PRIMARY group of the user
  # this will not work if the user belongs in secondary groups
  . "$CATALINA_HOME"/bin/setclasspath.sh
else
  if [ -r "$CATALINA_HOME"/bin/setclasspath.sh ]; then
    . "$CATALINA_HOME"/bin/setclasspath.sh
  else
    echo "Cannot find $CATALINA_HOME/bin/setclasspath.sh"
    echo "This file is needed to run this program"
    exit 1
  fi
fi

設定classpath，加入/bin/bootstrap.jar
if [ ! -z "$CLASSPATH" ] ; then
  CLASSPATH="$CLASSPATH":
fi
CLASSPATH="$CLASSPATH""$CATALINA_HOME"/bin/bootstrap.jar

日誌catalina.out
if [ -z "$CATALINA_OUT" ] ; then
  CATALINA_OUT="$CATALINA_BASE"/logs/catalina.out
fi
設定temp目錄
if [ -z "$CATALINA_TMPDIR" ] ; then
  # Define the java.io.tmpdir to use for Catalina
  CATALINA_TMPDIR="$CATALINA_BASE"/temp
fi

加入tomcat-juli.jar
if [ -r "$CATALINA_BASE/bin/tomcat-juli.jar" ] ; then
  CLASSPATH=$CLASSPATH:$CATALINA_BASE/bin/tomcat-juli.jar
else
  CLASSPATH=$CLASSPATH:$CATALINA_HOME/bin/tomcat-juli.jar
fi

沒有TTY禁止列印到控制檯，Cygwin環境處理
have_tty=0
if [ "`tty`" != "not a tty" ]; then
    have_tty=1
fi
if $cygwin; then
  JAVA_HOME=`cygpath --absolute --windows "$JAVA_HOME"`
  JRE_HOME=`cygpath --absolute --windows "$JRE_HOME"`
  CATALINA_HOME=`cygpath --absolute --windows "$CATALINA_HOME"`
  CATALINA_BASE=`cygpath --absolute --windows "$CATALINA_BASE"`
  CATALINA_TMPDIR=`cygpath --absolute --windows "$CATALINA_TMPDIR"`
  CLASSPATH=`cygpath --path --windows "$CLASSPATH"`
  [ -n "$JAVA_ENDORSED_DIRS" ] && JAVA_ENDORSED_DIRS=`cygpath --path --windows "$JAVA_ENDORSED_DIRS"`
fi

java啟動引數
if [ -z "$JSSE_OPTS" ] ; then
  JSSE_OPTS="-Djdk.tls.ephemeralDHKeySize=2048"
fi
JAVA_OPTS="$JAVA_OPTS $JSSE_OPTS"

# Register custom URL handlers
# Do this here so custom URL handles (specifically 'war:...') can be used in the security policy
JAVA_OPTS="$JAVA_OPTS -Djava.protocol.handler.pkgs=org.apache.catalina.webresources"

juli LogManager的日誌配置與類
if [ -z "$LOGGING_CONFIG" ]; then
  if [ -r "$CATALINA_BASE"/conf/logging.properties ]; then
    LOGGING_CONFIG="-Djava.util.logging.config.file=$CATALINA_BASE/conf/logging.properties"
  else
    # Bugzilla 45585
    LOGGING_CONFIG="-Dnop"
  fi
fi

if [ -z "$LOGGING_MANAGER" ]; then
  LOGGING_MANAGER="-Djava.util.logging.manager=org.apache.juli.ClassLoaderLogManager"
fi

設定預設許可權
if [ -z "$UMASK" ]; then
    UMASK="0027"
fi
umask $UMASK

Java 9 不支援 java.endorsed.dirs系統引數，處理
ENDORSED_PROP=ignore.endorsed.dirs
if [ -n "$JAVA_ENDORSED_DIRS" ]; then
    ENDORSED_PROP=java.endorsed.dirs
fi
if [ -d "$CATALINA_HOME/endorsed" ]; then
    ENDORSED_PROP=java.endorsed.dirs
fi

設定SecurityListener的umask
JAVA_OPTS="$JAVA_OPTS -Dorg.apache.catalina.security.SecurityListener.UMASK=`umask`"

nohup設定，是否掛起，後臺執行，還是一直顯示日誌，$hpux檔案剛開始初始false，HP-UX，惠普unix，是剛開始判斷系統
if [ -z "$USE_NOHUP" ]; then
    if $hpux; then
        USE_NOHUP="true"
    else
        USE_NOHUP="false"
    fi
fi
unset _NOHUP
if [ "$USE_NOHUP" = "true" ]; then
    _NOHUP="nohup"
fi

JAVA 9啟動引數
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.base/java.lang=ALL-UNNAMED"
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.base/java.io=ALL-UNNAMED"
JDK_JAVA_OPTIONS="$JDK_JAVA_OPTIONS --add-opens=java.rmi/sun.rmi.transport=ALL-UNNAMED"
export JDK_JAVA_OPTIONS

沒有tty，不列印到控制檯，輸出，指令碼判斷後的最終使用配置的環境變數設定
if [ $have_tty -eq 1 ]; then
  echo "Using CATALINA_BASE:   $CATALINA_BASE"
  echo "Using CATALINA_HOME:   $CATALINA_HOME"
  echo "Using CATALINA_TMPDIR: $CATALINA_TMPDIR"
  if [ "$1" = "debug" ] ; then
    echo "Using JAVA_HOME:       $JAVA_HOME"
  else
    echo "Using JRE_HOME:        $JRE_HOME"
  fi
  echo "Using CLASSPATH:       $CLASSPATH"
  if [ ! -z "$CATALINA_PID" ]; then
    echo "Using CATALINA_PID:    $CATALINA_PID"
  fi
fi


根據引數加入java啟動引數
startup.sh 傳來的是start，其他[jpda，debug，run，
start，stop，configtest，version]，沒有引數，就輸出幫助文件 Usage

先是判斷pid是否設定
elif [ "$1" = "start" ] ; then

  if [ ! -z "$CATALINA_PID" ]; then
    if [ -f "$CATALINA_PID" ]; then
      if [ -s "$CATALINA_PID" ]; then
        echo "Existing PID file found during start."
        if [ -r "$CATALINA_PID" ]; then
          PID=`cat "$CATALINA_PID"`
          ps -p $PID >/dev/null 2>&1
          if [ $? -eq 0 ] ; then
            echo "Tomcat appears to still be running with PID $PID. Start aborted."
            echo "If the following process is not a Tomcat process, remove the PID file and try again:"
            ps -f -p $PID
            exit 1
          else
            echo "Removing/clearing stale PID file."
            rm -f "$CATALINA_PID" >/dev/null 2>&1
            if [ $? != 0 ]; then
              if [ -w "$CATALINA_PID" ]; then
                cat /dev/null > "$CATALINA_PID"
              else
                echo "Unable to remove or clear stale PID file. Start aborted."
                exit 1
              fi
            fi
          fi
        else
          echo "Unable to read PID file. Start aborted."
          exit 1
        fi
      else
        rm -f "$CATALINA_PID" >/dev/null 2>&1
        if [ $? != 0 ]; then
          if [ ! -w "$CATALINA_PID" ]; then
            echo "Unable to remove or write to empty PID file. Start aborted."
            exit 1
          fi
        fi
      fi
    fi
  fi

刪除第一個引數，建立CATALINA_OUT，日誌輸出
shift
touch "$CATALINA_OUT"

判斷引數，Security Manager，處理，應該沒有
if [ "$1" = "-security" ] ; then 

走else
else
    eval $_NOHUP "\"$_RUNJAVA\"" "\"$LOGGING_CONFIG\"" $LOGGING_MANAGER $JAVA_OPTS $CATALINA_OPTS \
      -D$ENDORSED_PROP="\"$JAVA_ENDORSED_DIRS\"" \
      -classpath "\"$CLASSPATH\"" \
      -Dcatalina.base="\"$CATALINA_BASE\"" \
      -Dcatalina.home="\"$CATALINA_HOME\"" \
      -Djava.io.tmpdir="\"$CATALINA_TMPDIR\"" \
      org.apache.catalina.startup.Bootstrap "[email protected]" start \
      >> "$CATALINA_OUT" 2>&1 "&"

  fi

  if [ ! -z "$CATALINA_PID" ]; then
    echo $! > "$CATALINA_PID"
  fi

  echo "Tomcat started."
start 引數 完畢

上面最後eval 後面就是整個java啟動引數，tomcat是java專案所以還是java classpath 等等加引數啟動。