hadoop/hadoop-common-project/hadoop-common/src/main/bin/slaves.sh

#!/usr/bin/env bash

# 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.


# Run a shell command on all slave hosts.
#
# Environment Variables
#
#   HADOOP_SLAVES    File naming remote hosts.
#     Default is ${HADOOP_CONF_DIR}/slaves.
#   HADOOP_CONF_DIR  Alternate conf dir. Default is ${HADOOP_PREFIX}/conf.
#   HADOOP_SLAVE_SLEEP Seconds to sleep between spawning remote commands.
#   HADOOP_SSH_OPTS Options passed to ssh when running remote commands.
##

usage="Usage: slaves.sh [--config confdir] command..."

# if no args specified, show usage
if [ $# -le 0 ]; then
  echo $usage
  exit 1
fi

bin=`dirname "${BASH_SOURCE-$0}"`
bin=`cd "$bin"; pwd`

DEFAULT_LIBEXEC_DIR="$bin"/../libexec
HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
. $HADOOP_LIBEXEC_DIR/hadoop-config.sh


# Where to start the script, see hadoop-config.sh
# (it set up the variables based on command line options)
if [ "$HADOOP_SLAVE_NAMES" != '' ] ; then
  SLAVE_NAMES=$HADOOP_SLAVE_NAMES
else
  SLAVE_FILE=${HADOOP_SLAVES:-${HADOOP_CONF_DIR}/slaves}
  SLAVE_NAMES=$(cat "$SLAVE_FILE" | sed  's/#.*$//;/^$/d')
fi

# start the daemons
for slave in $SLAVE_NAMES ; do
 ssh $HADOOP_SSH_OPTS $slave $"${@// /\\ }" \
   2>&1 | sed "s/^/$slave: /" &
 if [ "$HADOOP_SLAVE_SLEEP" != "" ]; then
   sleep $HADOOP_SLAVE_SLEEP
 fi
done

wait