Location and startup

• zkCli.sh resides in the ZooKeeper installation’s bin directory.

$ ls $ZK_HOME/bin
zkCleanup.sh  zkCli.sh  zkEnv.sh  zkServer.sh

• Connect to a running server (single instance):

$ zkCli.sh -server 127.0.0.1:2181

• On successful connection, an interactive prompt appears. The prompt includes a monotonically increasing history index:

WatchedEvent state:SyncConnected type:None path:null
[zk: 127.0.0.1:2181(CONNECTED) 0]

Discovering available commands

Run help inside the shell to list supported operations:

[zk: 127.0.0.1:2181(CONNECTED) 0] help
ZooKeeper -server host:port cmd args
        ls path [watch]
        ls2 path [watch]
        get path [watch]
        stat path [watch]
        set path data [version]
        create [-s] [-e] path data acl
        delete path [version]
        getAcl path
        setAcl path acl
        sync path
        addauth scheme auth
        listquota path
        delquota [-n|-b] path
        setquota -n|-b val path
        history
        redo cmdno
        printwatches on|off
        close
        connect host:port
        quit

The numeric token in the prompt increments each time a command is executed and can be used by history/redo.

Non-interactive (one-shot) usage

Commands may be issued directly from the shell without entering interactive mode:

$ zkCli.sh -server 127.0.0.1:2181 stat /

General form:

zkCli.sh -server HOST:PORT COMMAND [ARGS]

Example:

$ zkCli.sh -server 127.0.0.1:2181 help

Command categorise

• Creation and deletion: create, delete
• Existence and metadata: stat
• Data access: get, set
• Children enumeration: ls, ls2
• Synchronization: sync
• Access control: getAcl, setAcl, addauth
• Session/utility: history, redo, printwatches, connect, quit

Working with znodes

Create a top-level znode and write initial data:

[zk: 127.0.0.1:2181(CONNECTED) 1] create /app "v1"
Created /app

Create a child znode with quoted payload:

[zk: 127.0.0.1:2181(CONNECTED) 2] create /app/config "alpha"
Created /app/config

List children of a path (non-rceursive):

[zk: 127.0.0.1:2181(CONNECTED) 3] ls /
[zookeeper, app]

[zk: 127.0.0.1:2181(CONNECTED) 4] ls /app
[config]

Read data and metadata to a znode:

[zk: 127.0.0.1:2181(CONNECTED) 5] get /app
v1
cZxid = 0x3
ctime = Tue Feb 20 10:02:31 UTC 2024
mZxid = 0x3
mtime = Tue Feb 20 10:02:31 UTC 2024
pZxid = 0x4
cversion = 1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 2
numChildren = 1

[zk: 127.0.0.1:2181(CONNECTED) 6] get /app/config
alpha
cZxid = 0x4
ctime = Tue Feb 20 10:03:02 UTC 2024
mZxid = 0x4
mtime = Tue Feb 20 10:03:02 UTC 2024
pZxid = 0x4
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 5
numChildren = 0

Show only status information (no data payload):

[zk: 127.0.0.1:2181(CONNECTED) 7] stat /app
cZxid = 0x3
ctime = Tue Feb 20 10:02:31 UTC 2024
mZxid = 0x3
mtime = Tue Feb 20 10:02:31 UTC 2024
pZxid = 0x4
cversion = 1
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 2
numChildren = 1

List children and include the parent’s stats in one call:

[zk: 127.0.0.1:2181(CONNECTED) 8] ls2 /
[zookeeper, app]
cZxid = 0x0
ctime = Thu Jan 01 00:00:00 UTC 1970
mZxid = 0x0
mtime = Thu Jan 01 00:00:00 UTC 1970
pZxid = 0x3
cversion = 0
dataVersion = 0
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 0
numChildren = 2

Modify an existing node’s data, returning the new metadata:

[zk: 127.0.0.1:2181(CONNECTED) 9] set /app "v2"
cZxid = 0x3
ctime = Tue Feb 20 10:02:31 UTC 2024
mZxid = 0xa
mtime = Tue Feb 20 10:10:15 UTC 2024
pZxid = 0x4
cversion = 1
dataVersion = 1
aclVersion = 0
ephemeralOwner = 0x0
dataLength = 2
numChildren = 1

Attempting to delete a non-empty node fails; remove children first:

[zk: 127.0.0.1:2181(CONNECTED) 10] delete /app
Node not empty: /app

[zk: 127.0.0.1:2181(CONNECTED) 11] delete /app/config
[zk: 127.0.0.1:2181(CONNECTED) 12] delete /app

History and replay

Display recent commands and their indices:

[zk: 127.0.0.1:2181(CONNECTED) 13] history
5 - get /app
6 - get /app/config
7 - stat /app
8 - ls2 /
9 - set /app "v2"
10 - delete /app
11 - delete /app/config
12 - delete /app
13 - history

Re-run a previous command by its number:

[zk: 127.0.0.1:2181(CONNECTED) 14] redo 8
[zookeeper, app]

Session termination

Exit the shell:

[zk: 127.0.0.1:2181(CONNECTED) 15] quit
Quitting...