继 HBase 客户端类型 （二）
4. HBase Shell 交互接口
HBase shell 是 HBase 集群的命令行接口。可以使用它连接到本地或远程服务器并与之交互。shell 提供了客户端和系统管理操作。
4.1 基础 (Basics)
-----------------------------------------------------------------------------------------------------------------------------------------
体验 shell 的第一步就是启动它：
$ $HBASE_HOME/bin/hbase shell
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 1.0.0, r6c98bff7b719efdb16f71606f3b7d8229445eb81, \
Sat Feb 14 19:49:22 PST 2015
hbase(main):001:0>HBase shell 是基于 JRuby 的，JRuby 是基于 Ruby 实现的 Java 虚拟机。更确切地说，它使用的是交互式 Ruby Shell(Interactive Ruby Shell, IRB)
即输入 Ruby 命令并立刻得到响应。HBase 携带的 Ruby 脚本扩展了 IRB，带有基于 Java API 的特殊命令。它继承了内置的命令历史和命令补全的支持，
以及所有的 Ruby 命令。
NOTE:
-------------------------------------------------------------------------------------------------------------------------------------
没有必要在机器上安装 Ruby, 因为 HBase 自带了执行 JRuby shell 必要的 JAR 文件。用户使用所提供的脚本在 Java 上启动 shell。
shell 启动后，可以输入 help 获得帮助文本：
hbase(main):001:0> help
HBase Shell, version 1.0.0,
r6c98bff7b719efdb16f71606f3b7d8229445eb81, \
Sat Feb 14 19:49:22 PST 2015
Type 'help "COMMAND"', (e.g. 'help "get"' -- the quotes are necessary)
\
for help on a specific command.
Commands are grouped. Type 'help "COMMAND_GROUP"', (e.g. 'help
"general"') \
for help on a command group.
COMMAND GROUPS:
Group name: general
Commands: status, table_help, version, whoami
Group name: ddl
Commands: alter, alter_async, alter_status, create, describe,
disable, \
disable_all, drop, drop_all, enable, enable_all, exists,
get_table, \
is_disabled, is_enabled, list, show_filters
...
SHELL USAGE:
Quote all names in HBase Shell such as table and column names.
Commas
delimit command parameters. Type <RETURN> after entering a command to run it.
Dictionaries of configuration used in the creation and alteration of tables
are Ruby Hashes. They look like this:
...如帮助文本中所描述的，可以请求特定命令的帮助，在调用 help 时将命令添加到后面，或者 help 命令后连接一个组名称，打印出这个组内所有命令的
帮助信息。命令或者组名称(command or group name) 必须使用引号括起来。
离开 shell, 输入 exit 或 quit:
hbase(main):002:0> exit
$shell 也包含特定的命令行选项，添加 -h 或 --help, 切换到命令行时会看到这些命令行选项：
$ $HBASE_HOME/bin/hbase shell -h
Usage: shell [OPTIONS] [SCRIPTFILE [ARGUMENTS]] --format=OPTION Formatter for outputting results. Valid options are: console, html. (Default: console)
-d | --debug Set DEBUG log levels.
-h | --help This help Debugging:
-------------------------------------------------------------------------------------------------------------------------------------
将 -d 或 --debug 开关添加到 shell 启动命令启用调试模式(debug mode), 即将日志级别切换到 DEBUG, 并且使 shell 打印出任何 backtrace 信息，
其类似于 Java 中的 stacktraces 信息。
如果已经在 shell 中，可以使用 debug 命令在调试模式间切换：
hbase(main):001:0> debug
Debug mode is ON
hbase(main):002:0> debug
Debug mode is OFF 可以使用 debug? 命令检查调试模式：
hbase(main):003:0> debug?
Debug mode is OFF
非调试模式下，shell 的日志级别为 ERROR, 并且不会在控制台上打印 backtrace 信息。
有一个选项用于切换在 shell 中的输出格式，至本文为止，虽然 CLI 帮助说也支持 html, 但只有 console 可用。设置除 console 以外的格式会产生错误
消息。
shell 启动脚本自动使用 $HBASE_HOME 目录配置相同的目录。用户可以使用其它设置覆盖这个位置，但最重要的是可以连接到不同的集群。新建一个包含
hbase-site.xml 文件的单独的目录，配置 hbase.zookeeper.quorum 属性指向一个不同的集群，然后像下面这样启动 shell:
$ HBASE_CONF_DIR="/<your-other-config-dir>/" bin/hbase shell注意，必须指定一个完整的目录，而不仅仅是 hbase-site.xml 文件。
4.2 命令 (Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
命令被分组为五个不同的类别，分别代表了它们的语义关系。在输入命令时，必须遵循下列原则：
● 引用名称 (Quote Names)
-------------------------------------------------------------------------------------------------------------------------------------
命令需要表或列的名称时，要将名称用单引号或双引号括起来。通常建议使用单引号。
● 引用值 (Quote Values)
-------------------------------------------------------------------------------------------------------------------------------------
shell 支持使用十六进制数或八进制表示二进制的输入和输出。必须使用双引号将它们括起来，否则 shell 会将它们解释为字面文本(literal)。
hbase> get 't1', "key\x00\x6c\x65\x6f\x6e"
hbase> get 't1', "key\000\154\141\165\162\141"
hbase> put 't1', "test\xef\xff", 'f1:', "\x01\x33\x70" 注意上述的混合引用，必须确保使用正确的引用，否则无法获取预期的结果。在单引号中的文本被当做字面文本(literal), 而双引号中的文本是被替换的
(interpolated), 也就是说，它会转换八进制或十六进制数值为多个字节。
● 使用逗号分隔参数 (Comma Delimiters for Parameters)
-------------------------------------------------------------------------------------------------------------------------------------
使用逗号分隔命令参数。例如：
hbase(main):001:0> get 'testtable', 'row-1', 'colfam1:qual1'
● Ruby 哈希属性 (Ruby Hashes for Properties)
-------------------------------------------------------------------------------------------------------------------------------------
对于某些命令，需要输入带有 key/value 对的 map 属性。使用 Ruby 哈希形式：
{'key1' => 'value1', 'key2' => 'value2', ...}
keys/value 对被包含在花括号中，key 和 value 之间使用 "=>" 分隔。通常 key 是预定义的常量，例如 NAME, VERSIONS, or COMPRESSION, 并且不
需要引号括起来。例如：
hbase(main):001:0> create 'testtable', { NAME => 'colfam1', VERSIONS => 1, TTL => 2592000, BLOCKCACHE => true }
限制输出 (Restricting Output)
-------------------------------------------------------------------------------------------------------------------------------------
get 命令有一个可选参数可以用于限制被打印值的长度。这对有多个列含有不同长度的值很有用。为了快速获得实际列的整体视图，可以抑制太长的值
打印完整的数据，否则控制台很快就变得难以控制。
下面的例子中，插入一个很长的值，并在之后的检索时使用 MAXLENGTH 参数限制了长度：
hbase(main):001:0> put 'testtable','rowlong','colfam1:qual1','abcdefghijklmnopqrstuvwxyzabcdefghi \
jklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcde \
...
xyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz'
hbase(main):018:0> get 'testtable', 'rowlong', MAXLENGTH => 60
COLUMN CELL
colfam1:qual1 timestamp=1306424577316, value=abcdefghijklmnopqrstuvwxyzabcMAXLENGTH 从行的开始处计算，也就是说，包括列的名称。设置的值为控制台的宽度或略小，这样可以在一行中显示每个列。
对于任何的命令，可以通过输入 help '<command>' 获取详细的帮助信息，例如：
hbase(main):001:0> help 'status'
Show cluster status. Can be 'summary', 'simple', 'detailed', or 'replication'. The default is 'summary'. Examples:
hbase> status
hbase> status 'simple'
hbase> status 'summary'
hbase> status 'detailed'
hbase> status 'replication'
hbase> status 'replication', 'source'
hbase> status 'replication', 'sink'
大多数命令都有一个直接匹配的客户端 API 或管理 API。后面几节将简要介绍每个命令以及这些 API 的功能。它们按照目的分组，并按分组中的命令排列：
Command Groups in HBase Shell
+-------------------+---------------------------------------------------------------------------------------------------
| Group | Description
+-------------------+---------------------------------------------------------------------------------------------------
| general | Comprises general commands that do not fit into any other category, for example status.
+-------------------+---------------------------------------------------------------------------------------------------
| configuration | Some configuration properties can be changed at runtime, and reloaded with these commands
+-------------------+---------------------------------------------------------------------------------------------------
| ddl | Contains all commands for data-definition tasks, such as creating a table
+-------------------+---------------------------------------------------------------------------------------------------
| namespace | Similar to the former, but for namespace related operations.
+-------------------+---------------------------------------------------------------------------------------------------
| dml | Has all the data-maipulation commands, which are used to insert or delete data, for example.
+-------------------+---------------------------------------------------------------------------------------------------
| snapshots | Tables can be saved using snapshots, which are created, deleted, restored, etc.
+-------------------+---------------------------------------------------------------------------------------------------
| tools | There are tools supplied with the shell that can help run expert-level, cluster wide operations.
+-------------------+---------------------------------------------------------------------------------------------------
| replication | All replication related commands are within this group, for example, adding a peer cluster
+-------------------+---------------------------------------------------------------------------------------------------
| security | The contained commands handle security related tasks
+-------------------+---------------------------------------------------------------------------------------------------
| visibility labels | These commands handle cell label related functionality, such as adding or listing labels
+-------------------+---------------------------------------------------------------------------------------------------可以使用任何组名称来获得帮助信息，使用 help '<groupname>' 语法，与命令的帮助语法相同。例如输入 help ddl 会打印出数据定义命令的完整帮助文本
■ 通用命令 (General Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
general 命令列于下表：
General Shell Commands
+---------------+---------------------------------------------------------------------------------------------------------------
| Command | Description
+---------------+---------------------------------------------------------------------------------------------------------------
| status | Returns various levels of information contained in the ClusterStatus class. See the help to get the simple,
| | summary, and detailed status information
+---------------+---------------------------------------------------------------------------------------------------------------
| version | Returns the current version, repository revision, and compilation date of your HBase cluster.
| | See ClusterStatus.getHBaseVersion()
+---------------+---------------------------------------------------------------------------------------------------------------
| table_help | Prints a help text explaining the usage of table references in the Ruby shell
+---------------+---------------------------------------------------------------------------------------------------------------
| whoami | Shows the current OS user and group membership known to HBase about the shell user
+---------------+---------------------------------------------------------------------------------------------------------------没有任何限定符运行 status 与执行 status 'summary' 相同，都打印出活动的和死掉的服务器数量，以及平均负载。平均负载是每台服务器持有的平均
region 的数量。status 'simple' 打印出有关活动服务器和死掉的服务器的详细信息，它们的服务器名，对于活动服务器还有高级的统计信息，类似于
web UI 中包含的请求数量，堆内存信息，磁盘以及 memstore 信息等等。最后，对于 detailed 版本的 status 命令，除了以上信息，还会打印出每个
region 当前所在的服务器信息。
另一组通用命令是与运行时更新服务器配置相关的：
Configuration Commands
+-------------------+-----------------------------------------------------------------------------------------------------------
| Commands | Description
+-------------------+-----------------------------------------------------------------------------------------------------------
| update_config | Update the configuration for a particular server. The name must be given as a valid server name
+-------------------+-----------------------------------------------------------------------------------------------------------
| update_all_config | Updates all region servers
+-------------------+-----------------------------------------------------------------------------------------------------------可以先用 status 命令获取服务器列表，然后使用返回的服务器名称调用更新配置命令。注意，需要对返回的服务器名称格式做些调整：服务
器名称组件由逗号分隔，而不是冒号或空格，如下示例：
hbase(main):001:0> status 'simple'
1 live servers
127.0.0.1:62801 1431177060772
...
Aggregate load: 0, regions: 4 hbase(main):002:0> update_config '127.0.0.1,62801,1431177060772'
0 row(s) in 0.1290 seconds hbase(main):003:0> update_all_config
0 row(s) in 0.0560 seconds
■ 名称空间和数据定义命令 (Namespace and Data Definition Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
namespace 组的命令提供 shell 的功能，用于处理创建，修改，以及删除名称空间。
Namespace Shell Commands:
+-----------------------+-------------------------------------------------------------------------------------------------------
| Commands | Description
+-----------------------+-------------------------------------------------------------------------------------------------------
| create_namespace | Creates a namespace with the provided name.
+-----------------------+-------------------------------------------------------------------------------------------------------
| drop_namespace | Removes the namespace, which must be empty, that is, it must not contain any tables.
+-----------------------+-------------------------------------------------------------------------------------------------------
| alter_namespace | Changes the namespace details by altering its configuration properties
+-----------------------+-------------------------------------------------------------------------------------------------------
| describe_namespace | Prints the details of an existing namespace
+-----------------------+-------------------------------------------------------------------------------------------------------
| list_namespace | Lists all known namespaces
+-----------------------+-------------------------------------------------------------------------------------------------------
| list_namespace_tables | Lists all tables contained in the given namespace
+-----------------------+-------------------------------------------------------------------------------------------------------数据定义(data definition) 命令列于下表，大多数来源于管理 API (administrative API):
Data Definition Shell Commands
+---------------+---------------------------------------------------------------------------------------------------------------
| Commands | Description
+---------------+---------------------------------------------------------------------------------------------------------------
| alter | Modifies an existing table schema using modifyTable().
+---------------+---------------------------------------------------------------------------------------------------------------
| alter_async | Same as above, but returns immediately without waiting for the changes to take effect
+---------------+---------------------------------------------------------------------------------------------------------------
| alter_status | Can be used to query how many regions have the changes applied to them. Use this after making asynchronous
| | alterations.
+---------------+---------------------------------------------------------------------------------------------------------------
| create | Creates a new table. See the createTable() call
+---------------+---------------------------------------------------------------------------------------------------------------
| describe | Prints the HTableDescriptor. A shortcut for this command is desc
+---------------+---------------------------------------------------------------------------------------------------------------
| disable | Disables a table. See the disableTable() method.
+---------------+---------------------------------------------------------------------------------------------------------------
| disable_all | Uses a regular expression to disable all matching tables in a single command
+---------------+---------------------------------------------------------------------------------------------------------------
| drop | Drops a table. See the deleteTable() method
+---------------+---------------------------------------------------------------------------------------------------------------
| drop_all | Drops all matching tables. The parameter is a regular expression
+---------------+---------------------------------------------------------------------------------------------------------------
| enable | Enables a table. See the enableTable() call
+---------------+---------------------------------------------------------------------------------------------------------------
| enable_all | Using a regular expression to enable all matching tables
+---------------+---------------------------------------------------------------------------------------------------------------
| exists | Checks if a table exists. It uses the tableExists() call
+---------------+---------------------------------------------------------------------------------------------------------------
| is_disabled | Checks if a table is disabled. See the isTableDisabled() method
+---------------+---------------------------------------------------------------------------------------------------------------
| is_enabled | Checks if a table is enabled. See the isTableEnabled() method
+---------------+---------------------------------------------------------------------------------------------------------------
| list | Returns a list of all user tables. Uses the listTables() method
+---------------+---------------------------------------------------------------------------------------------------------------
| show_filters | Lists all known filter classes.
+---------------+---------------------------------------------------------------------------------------------------------------
| get_table | Returns a table reference that can used in scripting
+---------------+---------------------------------------------------------------------------------------------------------------以 _all 结尾的命令接受正则表达式经命令应用到所有匹配的表。例如，假设系统中有一个名为 test 的表：
hbase(main):001:0> drop_all '.*'
test Drop the above 1 tables (y/n)?
y
1 tables successfully dropped hbase(main):002:0> drop_all '.*'
No tables matched the regex .*
■ 数据操纵命令 (Data Manipulation Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
数据操纵(data manipulation)命令列于下表，它们大多数由客户端 API 提供：
Data Manipulation Shell Commands
+-------------------+-----------------------------------------------------------------------------------------------------------
| Commands | Description
+-------------------+-----------------------------------------------------------------------------------------------------------
| put | Stores a cell. Uses the Put class
+-------------------+-----------------------------------------------------------------------------------------------------------
| get | Retrieves a cell. See the Get class
+-------------------+-----------------------------------------------------------------------------------------------------------
| delete | Deletes a cell
+-------------------+-----------------------------------------------------------------------------------------------------------
| deleteall | Similar to delete but does not require a column. Deletes an entire family or row
+-------------------+-----------------------------------------------------------------------------------------------------------
| append | Allows to append data to cells
+-------------------+-----------------------------------------------------------------------------------------------------------
| incr | Increments a counter. Uses the Increment class
+-------------------+-----------------------------------------------------------------------------------------------------------
| get_counter | Retrieves a counter value. Same as the get command but converts the raw counter value into a readable number
+-------------------+-----------------------------------------------------------------------------------------------------------
| scan | Scans a range of rows. Relies on the Scan class
+-------------------+-----------------------------------------------------------------------------------------------------------
| count | Counts the rows in a table. Uses a Scan internally
+-------------------+-----------------------------------------------------------------------------------------------------------
| truncate | Truncates a table, which is the same as executing the disable and drop commands, followed by a create,
| | using the same schema
+-------------------+-----------------------------------------------------------------------------------------------------------
| truncate_preserve | Same as the previous command, but retains the regions with their start and end keys.
+-------------------+-----------------------------------------------------------------------------------------------------------多个命令有扩展的可选参数，在 shell 中查看帮助获取详细信息。
格式化二进制数据 (Formatting Binary Data)
-------------------------------------------------------------------------------------------------------------------------------------
在 get 操作期间打印 cell 值时，shell 隐式使用 Bytes.toStringBinary() 转换二进制数据。可以在基于列的设置上改变这种行为，通过设定不同的
格式化方法。该方法必须接受一个 byte[] 数组并返回一个可打印的值的表现形式。它作为列名的一部分定义，作为 get 调用的可选参数输入：
<column family>[:<column qualifier>[:format method]]
对于 get 调用，可以忽略任何的列信息，但如果添加了信息，它们可以作为列族，或者列族和列限定符。第三个可选部分就是格式化方法，指向一个
Bytes 类的方法，或者一个自定义类的方法。因为其隐式地指明了列族和列限定符，因此意味着只能对一个特定的列指定一个格式化方法，而不能对整个
列族，甚至整个行设定。
下表列出了两个选项及其示例：
Possible Format Methods
+---------------+-------------------------------+--------------------------------------------------------------------------------
| Method | Examples | Description
+---------------+-------------------------------+--------------------------------------------------------------------------------
| Bytes Method | toInt, toLong | Refers to a known method from the Bytes class.
+---------------+-------------------------------+--------------------------------------------------------------------------------
| CustomMethod | c(CustomFormatClass).format | Specifies a custom class and method converting byte[] to text.
+---------------+-------------------------------+-------------------------------------------------------------------------------- Bytes Method 是对显式的 Bytes 类简单的快捷方式，例如，colfam:qual:c(org.apache.hadoop.hbase.util.Bytes).toInt 与 colfam:qual:toInt
相同。下面的示例使用了不同的命令展示讨论的内容：
hbase(main):001:0> create 'testtable', 'colfam1'
0 row(s) in 0.2020 seconds
=> Hbase::Table - testtable hbase(main):002:0> incr 'testtable', 'row-1', 'colfam1:cnt1'
0 row(s) in 0.0580 seconds hbase(main):003:0> get_counter 'testtable', 'row-1', 'col
fam1:cnt1', 1
COUNTER VALUE = 1 hbase(main):004:0> get 'testtable', 'row-1', 'colfam1:cnt1'
COLUMN CELL
colfam1:cnt1 timestamp=..., value=\x00\x00\x00\x00\x00\x00\x00\x01
1 row(s) in 0.0150 seconds hbase(main):005:0> get 'testtable', 'row-1', { COLUMN => 'colfam1:cnt1' }
COLUMN CELL
colfam1:cnt1 timestamp=..., value=\x00\x00\x00\x00\x00\x00\x00\x01
1 row(s) in 0.0160 seconds hbase(main):006:0> get 'testtable', 'row-1', { COLUMN => ['colfam1:cnt1:toLong'] }
COLUMN CELL
colfam1:cnt1 timestamp=..., value=1
1 row(s) in 0.0050 seconds hbase(main):007:0> get 'testtable', 'row-1', 'colfam1:cnt1:toLong'
COLUMN CELL
colfam1:cnt1 timestamp=..., value=1
1 row(s) in 0.0060 seconds
■ 快照命令 (Snapshot Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
这些命令反应了管理 API 功能。可以给一个表创建快照，用于之后的恢复或克隆，以及列出所有可用的快照等等。
Snapshot Shell Commands
+-----------------------+-------------------------------------------------------------------------------------------------------
| Command | Description
+-----------------------+-------------------------------------------------------------------------------------------------------
| snapshot | Creates a snapshot. Use the SKIP_FLUSH => true option to not flush the table before the snapshot.
+-----------------------+-------------------------------------------------------------------------------------------------------
| clone_snapshot | Clones an existing snapshot into a new table
+-----------------------+-------------------------------------------------------------------------------------------------------
| restore_snapshot | Restores a snapshot under the same table name as it was created
+-----------------------+-------------------------------------------------------------------------------------------------------
| delete_snapshot | Deletes a specific snapshot. The given name must match the name of a previously created snapshot
+-----------------------+-------------------------------------------------------------------------------------------------------
| delete_all_snapshot | Deletes all snapshots using a regular expression to match any number of names
+-----------------------+-------------------------------------------------------------------------------------------------------
| list_snapshots | Lists all snapshots that have been created so far
+-----------------------+-------------------------------------------------------------------------------------------------------创建一个快照可以指定模式，类似于 API 调用指定的模式，即可以强制刷写表的内存中的数据(默认行为)，或者只创建以及在磁盘上的文件的快照。
hbase(main):001:0> create 'testtable', 'colfam1'
0 row(s) in 0.4950 seconds
=> Hbase::Table - testtable
hbase(main):002:0> for i in 'a'..'z' do \
for j in 'a'..'z' do put 'testtable', "row-#{i}#{j}", "col
fam1:#{j}", \
"#{j}" end end
0 row(s) in 0.0830 seconds
0 row(s) in 0.0070 seconds
... hbase(main):003:0> count 'testtable'
676 row(s) in 0.1620 seconds => 676
hbase(main):004:0> snapshot 'testtable', 'snapshot1', { SKIP_FLUSH => true }
0 row(s) in 0.4300 seconds
hbase(main):005:0> snapshot 'testtable', 'snapshot2'
0 row(s) in 0.3180 seconds hbase(main):006:0> list_snapshots
SNAPSHOT TABLE + CREATION TIME
snapshot1 testtable (Sun May 10 20:05:11 +0200 2015)
snapshot2 testtable (Sun May 10 20:05:18 +0200 2015)
2 row(s) in 0.0560 seconds => ["snapshot1", "snapshot2"]
hbase(main):007:0> disable 'testtable'
0 row(s) in 1.2010 seconds hbase(main):008:0> restore_snapshot 'snapshot1'
0 row(s) in 0.3430 seconds hbase(main):009:0> enable 'testtable'
0 row(s) in 0.1920 seconds hbase(main):010:0> count 'testtable'
0 row(s) in 0.0130 seconds
=> 0
hbase(main):011:0> disable 'testtable'
0 row(s) in 1.1920 seconds hbase(main):012:0> restore_snapshot 'snapshot2'
0 row(s) in 0.4710 seconds hbase(main):013:0> enable 'testtable'
0 row(s) in 0.3850 seconds hbase(main):014:0> count 'testtable'
676 row(s) in 0.1670 seconds
=> 676
■ 工具命令 (Tool Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
tools 命令列于下表，这些命令都由管理 API 提供。这些命令很多是低级别的，也就是说，可能具有破坏性动作，因此确保仔细阅读每个命令的 shell 帮助
以理解它们的影响。
Tools Shell Commands
+-----------------------+-------------------------------------------------------------------------------------------------------
| Command | Description
+-----------------------+-------------------------------------------------------------------------------------------------------
| assign | Assigns a region to a server
+-----------------------+-------------------------------------------------------------------------------------------------------
| balance_switch | Toggles the balancer switch
+-----------------------+-------------------------------------------------------------------------------------------------------
| balancer | Starts the balancer
+-----------------------+-------------------------------------------------------------------------------------------------------
| close_region | Closes a region. Uses the closeRegion() method
+-----------------------+-------------------------------------------------------------------------------------------------------
| compact | Starts the asynchronous compaction of a region or table. Uses compact()
+-----------------------+-------------------------------------------------------------------------------------------------------
| compact_rs | Compact all regions of a given region server. The optional boolean flag decided between major and minor
| | compactions
+-----------------------+-------------------------------------------------------------------------------------------------------
| flush | Starts the asynchronous flush of a region or table. Uses flush()
+-----------------------+-------------------------------------------------------------------------------------------------------
| major_compact | Starts the asynchronous major compaction of a region or table. Uses majorCompact()
+-----------------------+-------------------------------------------------------------------------------------------------------
| move | Moves a region to a different server. See the move() call
+-----------------------+-------------------------------------------------------------------------------------------------------
| split | Splits a region or table. See the split() call
+-----------------------+-------------------------------------------------------------------------------------------------------
| merge_region | Merges two regions, specified as hashed names. The optional boolean flag allows merging of
| | non-subsequent regions
+-----------------------+-------------------------------------------------------------------------------------------------------
| unassign | Unassigns a region. See the unassign() call
+-----------------------+-------------------------------------------------------------------------------------------------------
| wal_roll | Rolls the WAL, which means close the current and open a new one
+-----------------------+-------------------------------------------------------------------------------------------------------
| catalogjanitor_run | Runs the system catalog janitor process, which operates in the background and cleans out obsolete files
+-----------------------+-------------------------------------------------------------------------------------------------------
| catalogjanitor_switch | Toggles the system catalog janitor process, either enabling or disabling it
+-----------------------+-------------------------------------------------------------------------------------------------------
|catalogjanitor_enabled | Returns the status of the catalog janitor background process
+-----------------------+-------------------------------------------------------------------------------------------------------
| zk_dump | Dumps the ZooKeeper details pertaining to HBase. This is a special function offered by an internal class.
| | The web-based UI of the HBase Master exposes the same information
+-----------------------+-------------------------------------------------------------------------------------------------------
| trace | Starts or stops a trace, using the HTrace framework
+-----------------------+-------------------------------------------------------------------------------------------------------
■ 复制命令 (Replication Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
Replication Shell Commands
+-----------------------+-------------------------------------------------------------------------------------------------------
| Command | Description
+-----------------------+-------------------------------------------------------------------------------------------------------
| add_peer | Adds a replication peer
+-----------------------+-------------------------------------------------------------------------------------------------------
| remove_peer | Removes a replication peer
+-----------------------+-------------------------------------------------------------------------------------------------------
| enable_peer | Enables a replication peer
+-----------------------+-------------------------------------------------------------------------------------------------------
| disable_peer | Disables a replication peer
+-----------------------+-------------------------------------------------------------------------------------------------------
| list_peers | List all previously added peers
+-----------------------+-------------------------------------------------------------------------------------------------------
| list_replicated_tables| Lists all tables and column families that have replication enabled on the current cluster
+-----------------------+-------------------------------------------------------------------------------------------------------
| set_peer_tableCFs | Sets specific column families that should be replicated to the given peer
+-----------------------+-------------------------------------------------------------------------------------------------------
| append_peer_tableCFs | Adds the given column families to the specified peer’s list of replicated column families
+-----------------------+-------------------------------------------------------------------------------------------------------
| remove_peer_tableCFs | Removes the given list of column families from the list of replicated families for the given peer
+-----------------------+-------------------------------------------------------------------------------------------------------
| show_peer_tableCFs | Lists the currently replicated column families for the given peer
+-----------------------+-------------------------------------------------------------------------------------------------------大多数的命令需要一个 peer ID, 应用各自的功能到指定的 peer 配置。可以添加一个 peer, 之后移除它，对已存在的 peer 启用或禁用复制，列出所有已知的
peer 或复制的表。
■ 安全命令 (Security Commands)
-----------------------------------------------------------------------------------------------------------------------------------------
这组命令可以划分为两个部分，一部分是访问控制列表(access control list)，另一部分是 visibility label 相关的命令。对于访问控制列表组可以授权
(grant), 吊销(revoke), 以及列出用户许可权限。注意，这些命令只有在 AccessController 协处理器启用时可用。
Security Shell Commands
+-------------------+-----------------------------------------------------------------------------------------------------------
| Command | Description
+-------------------+-----------------------------------------------------------------------------------------------------------
| grant | Grant the named access rights to the given user
+-------------------+-----------------------------------------------------------------------------------------------------------
| revoke | Revoke the previously granted rights of a given user
+-------------------+-----------------------------------------------------------------------------------------------------------
| user_permission | Lists the current permissions of a user. The optional regular expression filters the list
+-------------------+----------------------------------------------------------------------------------------------------------- 第二组安全相关的命令处理 cell 级别可视性标签(visibility labels), 再次提醒需要一些额外的配置才能使其工作，这里是在服务器进程中
启用额外的 VisibilityController 协处理器。
Visibility Label Shell Commands
+---------------+---------------------------------------------------------------------------------------------------------------
| Command | Description
+---------------+---------------------------------------------------------------------------------------------------------------
| add_labels | Adds a list of visibility labels to the system
+---------------+---------------------------------------------------------------------------------------------------------------
| list_labels | Lists all previously defined labels. An optional regular expression can be used to filter the list
+---------------+---------------------------------------------------------------------------------------------------------------
| set_auths | Assigns the given list of labels to the provided user ID.
+---------------+---------------------------------------------------------------------------------------------------------------
| get_auths | Returns the list of assigned labels for the given user
+---------------+---------------------------------------------------------------------------------------------------------------
| clear_auths | Removes all or only the specified list of labels from the named user.
+---------------+---------------------------------------------------------------------------------------------------------------
|set_visibility | Adds a visibility expression to one or more cell
+---------------+---------------------------------------------------------------------------------------------------------------
4.3 脚本应用 (Scripting)
-----------------------------------------------------------------------------------------------------------------------------------------
在 shell 中，可以交互式执行命令，立刻得到反馈信息。有时候，只想发送一个命令，或许是一个脚本由调度维护系统(如 cron 或 at)调用。用户还可以
通过管道(piping) 的形式运行命令：
$ echo "status" | bin/hbase shell
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 1.0.0, r6c98bff7b719efdb16f71606f3b7d8229445eb81, \
Sat Feb 14 19:49:22 PST 2015
status
1 servers, 2 dead, 3.0000 average load一旦命令运行完成，shell 会关闭并将控制返回给调用者。最后，可以输入整个脚本，由 shell 启动时执行：
$ cat ~/hbase-shell-status.rb
status
$ bin/hbase shell ~/hbase-shell-status.rb
1 servers, 2 dead, 3.0000 average load
HBase Shell; enter 'help<RETURN>' for list of supported commands.
Type "exit<RETURN>" to leave the HBase Shell
Version 1.0.0, r6c98bff7b719efdb16f71606f3b7d8229445eb81, Sat Feb
14 19:49:22 PST 2015 hbase(main):001:0> exit一旦脚本执行完成，可以继续在 shell 中工作，或者正常退出。也有选项可以使用原生 JRuby 解释器执行脚本，直接将它作为一个 Java 应用程序执行。
hbase 脚本设置的类路径(class path) 能够使用任何必要的 Java 类。下面示例简单地从远程集群检索 table 列表：
$ cat ~/hbase-shell-status-2.rb
include Java
import org.apache.hadoop.hbase.HBaseConfiguration
import org.apache.hadoop.hbase.client.HBaseAdmin
import org.apache.hadoop.hbase.client.ConnectionFactory
conf = HBaseConfiguration.create
connection = ConnectionFactory.createConnection(conf)
admin = connection.getAdmin
tables = admin.listTables
tables.each { |table| puts table.getNameAsString() } $ bin/hbase org.jruby.Main ~/hbase-shell-status-2.rb
testtable由于 HBase shell 基于 JRuby’s IRB, 因此可以使用 IRB 内置特性，如，命令补全和命令历史(command completion and history)。启用或配置这些特性
要在用户的 home 目录中创建一个 .irbrc 文件，该文件会在 shell 启动时读取：
$ cat ~/.irbrc
require 'irb/ext/save-history'
IRB.conf[:SAVE_HISTORY] = 100
IRB.conf[:HISTORY_FILE] = "#{ENV['HOME']}/.irb-save-history"
Kernel.at_exit do
IRB.conf[:AT_EXIT].each do |i|
i.call
end
end启用命令历史能保存执行过的 shell 命令。命令补全功能已由 HBase 脚本启用了。
交互式解释器具有执行 HBase 类和功能函数的优点，例如，某些应用要求写一个 Java 应用程序。下面的示例将从 Bytes.toBytes() 调用输出的二进制输出
转换为整型值：
hbase(main):001:0>
org.apache.hadoop.hbase.util.Bytes.toInt( "\x00\x01\x06[".to_java_bytes)
=> 67163注意 shell 如何将前三个不可见的字符编码为十六进制值，而第四个字符"[" 则作为一个字符打印。
另一个例子是将一个日期转换为 Linux 纪元数，再转换回人类可读的日期：
hbase(main):002:0> java.text.SimpleDateFormat.new("yyyy/MM/dd HH:mm:ss").parse("2015/05/12 20:56:29").getTime
=> 1431456989000
hbase(main):002:0> java.util.Date.new(1431456989000).toString
=> "Tue May 12 20:56:29 CEST 2015"也可以在一个循环中添加很多的 cell, 例如，使用测试数据填充表：
hbase(main):003:0> for i in 'a'..'z' do for j in 'a'..'z' do \
put 'testtable', "row-#{i}#{j}", "colfam1:#{j}", "#{j}" end end一个更复杂的循环填充计数器可能类似如下：
hbase(main):004:0> require 'date';
import java.lang.Long
import org.apache.hadoop.hbase.util.Bytes
(Date.new(2011, 01, 01)..Date.today).each { |x| put "testtable", "daily", \
"colfam1:" + x.strftime("%Y%m%d"), Bytes.toBytes(Long.new(rand * 4000).longValue).to_a.pack("CCCCCCCC") }shell 的 JRuby 代码封装了很多 Java 类，例如 Table, Admin 为其自己的版本，更便于访问它们自己的功能，在执行复杂的脚本任务时，可以使用这些类
执行 table_help 命令，可以访问内建的帮助文本，说明如何使用 shell 封装的类，以及特别是 table 参考。这时可能会比较好奇，为什么 shell 执行某些
特定命令，如 create 时，它的响应有时会带有哈希箭头(hash rocket, or fat comma, 即 =>)：
hbase(main):005:0> create 'testtable', 'colfam1'
0 row(s) in 0.1740 seconds
=> Hbase::Table - testtablecreate 命令实际上返回一个引用，指向一个 Hbase::Table 实例，也就是指向新创建的 testtable. 可以利用这个引用在一个变量中对其排序，并且可以
使用 shell 的双 tab (double tab) 特性获取它提供的所有功能(functions it exposes)：
NOTE:
---------------------------------------------------------------------------------------------------------------------------------
进行下面的步骤时要删除之前创建的测试表，使用 disable 'testtable' , 然后在执行 drop 'testtable'
hbase(main):006:0> tbl = create 'testtable', 'colfam1'
0 row(s) in 0.1520 seconds
=> Hbase::Table - testtable
hbase(main):006:0> tbl. TAB TAB
...
tbl.append tbl.close
tbl.delete
tbl.deleteall tbl.describe
tbl.disable
...
tbl.help tbl.incr
tbl.name
tbl.put tbl.snapshot
tbl.table
...可以看到 table Ruby 类(这里是变量名 tbl)显露出的具有相同名称的所有 shell 命令。例如 put 命令实际上是 table.put 方法的快捷方式。table.help
打印出与 table_help 相同的内容，table.table 是 Java Table 实例的引用。如果没有其它选择可用，可以使用后者访问原生 API.
获取同一 Ruby table 引用的另一个方法时利用 get_table 命令，如果表已经存在这个方法很有用。
hbase(main):006:0> tbl = get_table 'testtable'
0 row(s) in 0.0120 seconds => Hbase::Table - testtable一旦拥有了引用，就可以使用匹配的方法调用任何命令，不需要再输入表的名称：
hbase(main):007:0> tbl.put 'row-1', 'colfam1:qual1', 'val1'
0 row(s) in 0.0050 seconds使用给定的值插入到测试表的命名的行和列。以同样的方法可以访问数据：
hbase(main):008:0> tbl.get 'row-1'
COLUMN CELL
colfam1:qual1 timestamp=1431506646925, value=val1
1 row(s) in 0.0390 seconds也可以使用 tbl.scan 等方法读取数据。所有与表相关的命令，都将表名作为第一个参数，也应使用表引用语法。输入 tbl.help '<command>' 命令以查看
shell 内置的命令帮助，通常也包含引用语法的示例。
一般的管理操作也是直接作用到一个表上，例如，enable, disable, 以及 drop 等，通过输入 tbl.enable, tbl.flush 等执行操作。注意，删除(drop)
一个表之后，它的引用就变得没用了，再使用它是未定义的，不建议这样使用。
最后，另一个例子是围绕自定义序列化和格式化的。假设已存储 Java 对象到一个表中，并且打算重建实例，打印出所存储对象的文本表示。之前已经看到，
可以在通过 get 命令获取列时提供一个自定义的格式化方法。另外，HBase 携带的 Apache Commons Lang artifacts 使用其包含的 SerializationUtils 类
该类有静态的 serialize() 和 deserialize() method, 可以处理任何实现了 Serializable 接口的 Java 对象。下面的示例深入 shell 环境中，必须创建
自己的 Put 实例。这是必要的，因为 shell 提供的 put 命令假设其值为一个字符串。让我们的例子工作，需要访问原生 Put 类方法：
hbase(main):004:0> import org.apache.commons.lang.SerializationUtils
=> Java::OrgApacheCommonsLang::SerializationUtils hbase(main):002:0> create 'testtable', 'colfam1'
0 row(s) in 0.1480 seconds hbase(main):003:0> p = org.apache.hadoop.hbase.client.Put.new("row-1000".to_java_bytes)
=> #<Java::OrgApacheHadoopHbaseClient::Put:0x6d6bc0eb> hbase(main):004:0> p.addColumn("colfam1".to_java_bytes,
"qual1".to_java_bytes, SerializationUtils.serialize(java.util.ArrayList.new([1,2,3])))
=> #<Java::OrgApacheHadoopHbaseClient::Put:0x6d6bc0eb> hbase(main):005:0> t.table.put(p)
hbase(main):006:0> scan 'testtable'
ROW COLUMN+CELL
row-1000 column=colfam1:qual1, timestamp=1431353253936, \
value=\xAC\xED\x00\x05sr\x00\x13java.util.ArrayListx\x81\xD2\x1D
\x99...
\x03sr\x00\x0Ejava.lang.Long;\x8B\xE4\x90\xCC\x8F#\xDF
\x02\x00\x01J...
\x10java.lang.Number\x86\xAC\x95\x1D\x0B\x94\xE0\x8B
\x02\x00\x00xp...
1 row(s) in 0.0340 seconds hbase(main):007:0> get 'testtable', 'row-1000', 'colfam1:qual1:c(SerializationUtils).deserialize'
COLUMN CELL
colfam1:qual1 timestamp=1431353253936, value=[1, 2, 3]
1 row(s) in 0.0360 seconds hbase(main):008:0> p.addColumn("colfam1".to_java_bytes, "qual1".to_java_bytes, SerializationUtils.serialize( \
java.util.ArrayList.new(["one", "two", "three"])))
=> #<Java::OrgApacheHadoopHbaseClient::Put:0x6d6bc0eb>
hbase(main):009:0> t.table.put(p)
hbase(main):010:0> scan 'testtable'
ROW COLUMN+CELL
row-1000 column=colfam1:qual1, timestamp=1431353620544, \
value=\xAC\xED\x00\x05sr\x00\x13java.util.ArrayListx\x81\xD2\x1D\x99 \
\xC7a\x9D\x03\x00\x01I\x00\x04sizexp\x00\x00\x00\x03w
\x04\x00\x00\x00 \
\x03t\x00\x03onet\x00\x03twot\x00\x05threex
1 row(s) in 0.4470 seconds
hbase(main):011:0> get 'testtable', 'row-1000', 'colfam1:qual1:c(SerializationUtils).deserialize'
COLUMN CELL
colfam1:qual1 timestamp=1431353620544, value=[one, two, three]
1 row(s) in 0.0190 seconds首先导入 org.apache.commons.lang.SerializationUtils 类(已在 HBase shell 类路径中), 然后创建了一个测试表，跟一个自定义 Put 实例。设置了 put
实例两次，一次序列化数字数组，一次序列化字符串数组。之后调用封装的 Table 实例的 put 方法，并扫描内容验证序列化内容。
每一次序列化之后，调用了 get 命令，通过自定义的格式化方法指向 deserialize() method. 它解析原始字节反序列化为一个 Java 对象，然后打印出来。
由于 shell 应用 toString() 调用，因此可以看到打印出的数组的原始内容，如 [one, two, three]. 这确认了直接在 shell 中重建了序列化的 Java 对象。
参考：
HBase 客户端类型 （一）
HBase 客户端类型 （二）
HBase 客户端类型 （三）
HBase 客户端类型 （四）
参考：
《HBase - The Definitive Guide - 2nd Edition》Early release —— 2015.7 Lars George
