source: nutchez-0.1/bin/start-dfs.sh @ 78

#!/usr/bin/env bash

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# this work for additional information regarding copyright ownership.
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#
#     http://www.apache.org/licenses/LICENSE-2.0
#
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# Start hadoop dfs daemons.
# Optinally upgrade or rollback dfs state.
# Run this on master node.

usage="Usage: start-dfs.sh [-upgrade|-rollback]"

bin=`dirname "$0"`
bin=`cd "$bin"; pwd`

. "$bin"/hadoop-config.sh

# get arguments
if [ $# -ge 1 ]; then
  nameStartOpt=$1
  shift
  case $nameStartOpt in
    (-upgrade)
      ;;
    (-rollback) 
      dataStartOpt=$nameStartOpt
      ;;
    (*)
      echo $usage
      exit 1
      ;;
  esac
fi

# start dfs daemons
# start namenode after datanodes, to minimize time namenode is up w/o data
# note: datanodes will log connection errors until namenode starts
"$bin"/hadoop-daemon.sh --config $HADOOP_CONF_DIR start namenode $nameStartOpt
"$bin"/hadoop-daemons.sh --config $HADOOP_CONF_DIR start datanode $dataStartOpt
"$bin"/hadoop-daemons.sh --config $HADOOP_CONF_DIR --hosts masters start secondarynamenode