Hadoop Shell 介绍

以 hadoop 2.7.3 为例　　

bin 目录下是最基础的集群管理脚本, 用户可通过该脚本完成各种功能, 如 HDFS 管理, MapReduce 作业管理等.

　　作为入门, 先介绍bin 目录下的 hadoop 脚本的使用方法, 如下所示:   参考 官网的Hadoop 命令参考

Usage: hadoop [--config confdir] [COMMAND | CLASSNAME]
  CLASSNAME            run the class named CLASSNAME
 or
  where COMMAND is one of:
  fs                   run a generic filesystem user client
  version              print the version
  jar <jar>            run a jar file
                       note: please use "yarn jar" to launch
                             YARN applications, not this command.
  checknative [-a|-h]  check native hadoop and compression libraries availability
  distcp <srcurl> <desturl> copy file or directories recursively
  archive -archiveName NAME -p <parent path> <src>* <dest> create a hadoop archive
  classpath            prints the class path needed to get the
  credential           interact with credential providers
                       Hadoop jar and the required libraries
  daemonlog            get/set the log level for each daemon
  trace                view and modify Hadoop tracing settings

Most commands print help when invoked w/o parameters.

hadoop 对应在 hadoop-2.7.3/bin/hadoop , 相关 shell 代码如下: ( fs 对应 org.apache.hadoop.fs.FsShell , jar 对应 org.apache.hadoop.util.RunJar )

// 这段在 hadoop-2.7.3/bin/hadoop
    # the core commands
    ......
    if [ "$COMMAND" = "fs" ] ; then
      CLASS=org.apache.hadoop.fs.FsShell
    elif [ "$COMMAND" = "version" ] ; then
      CLASS=org.apache.hadoop.util.VersionInfo
    elif [ "$COMMAND" = "jar" ] ; then
      CLASS=org.apache.hadoop.util.RunJar
      if [[ -n "${YARN_OPTS}" ]] || [[ -n "${YARN_CLIENT_OPTS}" ]]; then
        echo "WARNING: Use \"yarn jar\" to launch YARN applications." 1>&2
      fi
    ......

　　bin 目录下的 hdfs 脚本的使用方法, 如下所示:  参考 官网的 HDFS 命令参考

Usage: hdfs [--config confdir] [--loglevel loglevel] COMMAND
       where COMMAND is one of:
  dfs                  run a filesystem command on the file systems supported in Hadoop.
  classpath            prints the classpath
  namenode -format     format the DFS filesystem
  secondarynamenode    run the DFS secondary namenode
  namenode             run the DFS namenode
  journalnode          run the DFS journalnode
  zkfc                 run the ZK Failover Controller daemon
  datanode             run a DFS datanode
  dfsadmin             run a DFS admin client
  haadmin              run a DFS HA admin client
  fsck                 run a DFS filesystem checking utility
  balancer             run a cluster balancing utility
  jmxget               get JMX exported values from NameNode or DataNode.
  mover                run a utility to move block replicas across
                       storage types
  oiv                  apply the offline fsimage viewer to an fsimage
  oiv_legacy           apply the offline fsimage viewer to an legacy fsimage
  oev                  apply the offline edits viewer to an edits file
  fetchdt              fetch a delegation token from the NameNode
  getconf              get config values from configuration
  groups               get the groups which users belong to
  snapshotDiff         diff two snapshots of a directory or diff the
                       current directory contents with a snapshot
  lsSnapshottableDir   list all snapshottable dirs owned by the current user
                        Use -help to see options
  portmap              run a portmap service
  nfs3                 run an NFS version 3 gateway
  cacheadmin           configure the HDFS cache
  crypto               configure HDFS encryption zones
  storagepolicies      list/get/set block storage policies
  version              print the version

Most commands print help when invoked w/o parameters.

　　bin 目录下的 mapred 脚本的使用方法, 如下所示: 参考 官网的 MapReduce 命令参考

Usage: mapred [--config confdir] [--loglevel loglevel] COMMAND
       where COMMAND is one of:
  pipes                run a Pipes job
  job                  manipulate MapReduce jobs
  queue                get information regarding JobQueues
  classpath            prints the class path needed for running
                       mapreduce subcommands
  historyserver        run job history servers as a standalone daemon
  distcp <srcurl> <desturl> copy file or directories recursively
  archive -archiveName NAME -p <parent path> <src>* <dest> create a hadoop archive
  hsadmin              job history server admin interface

Most commands print help when invoked w/o parameters.

　　bin 目录下的 yarn 脚本的使用方法, 如下所示: 参考 官网的 YARN 命令

Usage: yarn [--config confdir] [COMMAND | CLASSNAME]
  CLASSNAME                             run the class named CLASSNAME
 or
  where COMMAND is one of:
  resourcemanager -format-state-store   deletes the RMStateStore
  resourcemanager                       run the ResourceManager
  nodemanager                           run a nodemanager on each slave
  timelineserver                        run the timeline server
  rmadmin                               admin tools
  sharedcachemanager                    run the SharedCacheManager daemon
  scmadmin                              SharedCacheManager admin tools
  version                               print the version
  jar <jar>                             run a jar file
  application                           prints application(s)
                                        report/kill application
  applicationattempt                    prints applicationattempt(s)
                                        report
  container                             prints container(s) report
  node                                  prints node report(s)
  queue                                 prints queue information
  logs                                  dump container logs
  classpath                             prints the class path needed to
                                        get the Hadoop jar and the
                                        required libraries
  cluster                               prints cluster information
  daemonlog                             get/set the log level for each
                                        daemon

Most commands print help when invoked w/o parameters.

　　bin 目录下的 rcc 脚本的使用方法, 如下所示:

Usage: rcc --language [java|c++] ddl-files

　　其中, --config 用于设置Hadoop 配置文件目录. 默认目录为 ${HADOOP_HOME}/etc/hadoop. 而 COMMAND 是具体的某个命令, 常用的是 hadoop 的管理命令 fs, 作业提交命令 jar 等. CLASSNAME 指运行名为 CLASSNAME 的类 .