hadoop入门-查看启动脚本

1、 hadoop-daemon.sh(三个节点namenode、secondarynamenode、datanode)

 hadoop_rotate_log $log
    echo starting $command, logging to $log
    cd "$HADOOP_PREFIX"
    case $command in
      namenode|secondarynamenode|datanode|journalnode|dfs|dfsadmin|fsck|balancer|zkfc)
        if [ -z "$HADOOP_HDFS_HOME" ]; then
          hdfsScript="$HADOOP_PREFIX"/bin/hdfs
        else
          hdfsScript="$HADOOP_HDFS_HOME"/bin/hdfs
        fi
        nohup nice -n $HADOOP_NICENESS $hdfsScript --config $HADOOP_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
      ;;
      (*)
        nohup nice -n $HADOOP_NICENESS $hadoopScript --config $HADOOP_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
      ;;

2、start-dfs.sh（一次启动三个节点，主节点连接到从节点）

NAMENODES=$($HADOOP_PREFIX/bin/hdfs getconf -namenodes)
echo "Starting namenodes on [$NAMENODES]"
"$HADOOP_PREFIX/sbin/hadoop-daemons.sh" \
  --config "$HADOOP_CONF_DIR" \
  --hostnames "$NAMENODES" \
  --script "$bin/hdfs" start namenode $nameStartOpt

3、hadoop-daemons.sh(启动的时候需要用的ssh协议）

exec "$bin/slaves.sh" --config $HADOOP_CONF_DIR cd "$HADOOP_PREFIX" \; "$bin/hadoop-daemon.sh" --config $HADOOP_CONF_DIR "$@"

4、 yarn-daemon.sh

 if [ "$YARN_MASTER" != "" ]; then
      echo rsync from $YARN_MASTER
      rsync -a -e ssh --delete --exclude=.svn --exclude='logs/*' --exclude='contrib/hod/logs/*' $YARN_MASTER/ "$HADOOP_YARN_HOME"
    fi

    hadoop_rotate_log $log
    echo starting $command, logging to $log
    cd "$HADOOP_YARN_HOME"
    nohup nice -n $YARN_NICENESS "$HADOOP_YARN_HOME"/bin/yarn --config $YARN_CONF_DIR $command "$@" > "$log" 2>&1 < /dev/null &
    echo $! > $pid
    sleep 1
    head "$log"
    # capture the ulimit output
    echo "ulimit -a" >> $log
    ulimit -a >> $log 2>&1

5、start-yarn.sh

# start resourceManager
"$bin"/yarn-daemon.sh --config $YARN_CONF_DIR  start resourcemanager
# start nodeManager
"$bin"/yarn-daemons.sh --config $YARN_CONF_DIR  start nodemanager

6 、start-all.sh（不推荐使用）

# start hdfs daemons if hdfs is present
if [ -f "${HADOOP_HDFS_HOME}"/sbin/start-dfs.sh ]; then
"${HADOOP_HDFS_HOME}"/sbin/start-dfs.sh --config $HADOOP_CONF_DIR
fi
# start yarn daemons if yarn is present
if [ -f "${HADOOP_YARN_HOME}"/sbin/start-yarn.sh ]; then
"${HADOOP_YARN_HOME}"/sbin/start-yarn.sh --config $HADOOP_CONF_DIR
fi

总结：上面可以看出：调用 start-dfs.sh启动文件系统，实际上是调用hadoop-daemons.sh

                                        调用start-yarn.sh启动资源管理系统，实际上是调用了yarn-daemon.sh

                                        调用start-all.sh启动文件系统和资源管理系统，实际上是调用了start-dfs.sh和start-yarn.sh