Zookeeper Series 3: zookeeper commands, command line tools, and simple operations

Problem Guidance
1. What Common commands does zookeeper contain?
2. What command can be used to list the watch details of the server?
3. What operations does zookeeper contain?
4. How does zookeeper create zookeeper?



Common commands

Zookeeper supports the interaction between certain four-character command letters. Most of them are query commands used to obtain the current status and related information of the zookeeper service. You can use Telnet or NC to submit commands to zookeeper on the client. Common four-character commands for zookeeper are shown in table 1 below:

 

Table 1: zookeeper command

 

Zookeeper command	Function Description
Conf	Output detailed service configuration information.
Cons	Lists the full connection/session details of all clients connected to the server. Including the number of "Accept/Send" packets, session ID, Operation delay, and last operation execution.
Dump	Lists unprocessed sessions and temporary nodes.
ENVI	Output detailed information about the service environment (different from the conf command ).
Reqs	List unprocessed requests
Ruok	Test whether the service is in the correct status. If so, the service returns "imok"; otherwise, no response is made.
Stat	Output A list of performance and connected clients.
Wchs	List the detailed information of the server watch.
Wchc	A session is used to list the detailed information of the server watch. Its output is a list of watch-related sessions.
Wchp	List the detailed information of the server watch in the path. It outputs a session-related path.

 

1 is a simple example of the zookeeper command:

 

<Ignore_js_op> Figure 1: zookeeper Command case

 

Command line tool:

 

After the zookeeper service is successfully started, enter the following command to connect to the zookeeper service:

1. Zkcli. Sh-server 10.77.20.23: 2181

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After the connection is successful, the system outputs the relevant environment and configuration information of zookeeper, and outputs "Welcome to zookeeper" and other information on the screen. After you enter help, the available zookeeper commands are displayed, as shown in 1:

 

<Ignore_js_op> Figure 1: zookeeper command

 

Zookeeper simple operation 1) Use the LS command to view the content contained in the current zookeeper:

1. [ZK: 10.77.000023: 2181 (connected) 1] ls/
2. [Zookeeper]

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2) create a new znode and use create/ZK mydata. This command creates a new znode node "zk" and the strings associated with it:

1. <Div style = "text-align: Left;"> <span style = "line-Height: 1.5;"> [ZK: 10.77.20.23: 2181 (connected) 2] Create/ZK mydata </span> </div> <Div style = "text-align: Left;"> <span style = "line-Height: 1.5; "> created/ZK </span> </div>

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3) run the LS command again to view the content contained in zookeeper:

1. [ZK: 10.77.000023: 2181 (connected) 3] ls/
2. [ZK, Zookeeper]

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4) run the GET command to check whether the znode created in step 2 contains the string we created:

1. [ZK: 10.77.000023: 2181 (connected) 4] GET/ZK
2. Mydata
3. Zxid = 0x40000000c
4. Time = Tue Jan 18 18:48:39 CST 2011
5. Zxid = 0x40000000c
6. Mtime = Tue Jan 18 18:48:39 CST 2011
7. Pzxid = 0x40000000c
8. Cversion = 0
9. Dataversion = 0
10. Aclversion = 0
11. Ephemeralowner = 0x0
12. Datalength = 6
13. Numchildren = 0

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5) Below we use the set command to set the string associated with ZK:

1. [ZK: 10.77.000023: 2181 (connected) 5] Set/ZK shenlan211314
2. Czxid = 0x40000000c
3. Ctime = Tue Jan 18 18:48:39 CST 2011
4. Mzxid = 0x40000000d
5. Mtime = Tue Jan 18 18:52:11 CST 2011
6. Pzxid = 0x40000000c
7. Cversion = 0
8. Dataversion = 1
9. Aclversion = 0
10. Ephemeralowner = 0x0
11. Datalength = 13
12. Numchildren = 0

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6) Below we will delete the created znode:

1. [ZK: 10.77.000023: 2181 (connected) 6] delete/ZK

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7) run the LS command again to view the content of zookeeper:

1. [ZK: 10.77.000023: 2181 (connected) 7] ls/
2. [Zookeeper]

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After verification, the zk node has been deleted. Article transferred from: http://www.aboutyun.com/thread-9310-1-1.html

Zookeeper Series 3: zookeeper commands, command line tools, and simple operations