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Manual Reference Pages  -  JMX4PERL (1)

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jmx4perl - JMX access tools and modules



  jmx4perl .... http://server:8080/jolokia ["info"]

  jmx4perl .... <agent-url> read <mbean-name> <attribute-name> [path]

  jmx4perl .... <agent-url> write <mbean-name> <attribute-name> <value> [path]

  jmx4perl .... <agent-url> exec <mbean-name> <operation> <arg1> <arg2> ...

  jmx4perl .... <agent-url> search <mbean pattern>

  jmx4perl .... <agent-url> list [<domain-name>[:<mbean name>]]

  jmx4perl .... <agent-url> attributes [max-depth max-list-size max-objects]

  jmx4perl .... aliases

  jmx4perl .... encrypt <password>

  jmx4perl --help

  jmx4perl --version [<agent-url>]


   --product <id>          Product to use for aliasing (ommits autodetection)
   --user <user>           Credential used for authentication  
   --password <pwd> 
   --proxy <url>           URL to proxy
   --proxy-user <user>     Authentication information for a proxy
   --proxy-password <pwd>
   --target <jmx-url>      JSR-160 JMX Service URL to be used as the target server
   --target-user <user>    Credential for the target server if --target is given
   --target-password <pwd>
   --config                Path to an optional configuration file (default: ~/.j4p)
   --history               Print out the history of return values (if switched on and present)
   --legacy-escape         Used for contacting pre 1.0 Jolokia agent for MBeans containing
                           slashes in their name.
   --method <get|post>     Method to be used for HTTP request ("get" or "post")
   --option key=val        Options for tuning the output of jmx4perl. Known keys are
                              format   : Either json or data
                              booleans : Pair of strings separated by slash to use for printing
                                         boolean values (Default: [true]/[false])
                              indent   : Space indent when printing complex data structures
   --verbose               Print out more information


<B>jmx4perlB> is a command line utility for an easy access of an instrumented application server. Before you can use this tool, you need to deploy a small agent application. In the following agent-url is the URL for accessing this agent. If you use a configuration file, you can use also a symbolic name as stored in the configuration file. See JMX::Jmx4Perl::Manual for details.

With the --option (or -o for short) the output of <B>jmx4perlB> can be tuned. I.e. the way boolean values are printed can be tuned as well as the data format to use for complex data structure. The known options are
format the value an be either json or <data> for printing out complex data as JSON or as a Perl data structure. Default is data.
booleans Specify the pair of strings to use for boolean values for the data output format. The value of this option should be given as a string separated with a /. The default value is [true]/[false].
method Specify the HTTP method to use for requesting the server. This can either be get or post. By default get is used.
legacy-escape Prior to version 1.0 Jolokia used a different escaping scheme for GET requests which contains slashes. This option must be used, when the server-side agent has a version < 1.0 and the MBean name contains slashes (/). Alternatively, --method post can be used, since the post method doesn’t suffer from any escaping issues.
indent Number of spaces to use for indenting the output of complex data structures. Default are 4 spaces.
The options can be also put into the configuration file in a section called Jmx4Perl. For example:

      # json or data
      Format json

      # Boolean values: Default is [true]/[false]
      Booleans 0/1

      # Number of spaces to indent for complex
      # data structures
      Indent 4

<B>jmx4perlB> serves also an example of how to use the JMX::Jmx4Perl package. See its documentation for more details on how to embed JMX access into your programs.



If you use jmx4perl without any command or with info as command, you get a description about the server, including the application server’s product name and version. This works by autodetection and only for the supported application servers (see JMX::Jmx4Perl::Manual for a list of supported products). The only argument required is the url which points to the deployed jmx4perl agent.

With --verbose info prints the system properties and runtime arguments as well.


List meta data of all registered mbeans on the target application server. This includes attributes and operations along whith their descriptions and parameters (as far as they are provided by mbean’s info).

You can provide an inner path as an additional argument as well. See JMX::Jmx4Perl::Request for an explanation about inner paths (in short, it’s some sort of XPath expression which selects only a subset of all MBeans and their values). See JMX::Jmx4Perl, method list() for a more rigorous documentation abouting listing of MBeans.


Show all attributes of all registerd mbeans and their values. For simple scalar values they are shown on one line, for more complex data structures, Data::Dumper is used. Please note, that it is normal, that for certain attributes an error is returned (i.e. when this attribute is not implemented on the server side e.g. or an MXMbean). To see the full server side stacktrace for this errors, use --verbose as command line option

The attribute list can get quite large (moren than 200 MB for JBoss 5). To restrict the output you can use the following extra optional parameters (given in this order):
maxDepth Maximum nesting level of the returned JSON structure for a certain MBean (default: 5)
maxCollectionSize Maximum size of a collection after which it gets truncated (default: 150)
maxObjects Maximum overall objects to fetch for a certain MBean (default: 1000)
In the case of truncation, the JSON answer contains marker entries like [Object limit exceeded] or [Depth limit ...]. Loops are detected, too which results in markers of the form [Reference ...]

    read / get

Read an JMX attribute’s value and print it out. The required arguments are the MBean’s name and the attribute’s name. Additionally, you can provide a path within the return value to pick a sub-value. See JMX::Jmx4Perl::Request for a detailed explanation of paths.

The MBean’s name and the attribute can be substituted by an alias name, too.

For a single value, the value itself is printed (without additional newline), for a more complex data structure, Data::Dumper is used.

If the option --history is given and history tracking is switched on (see below), then the stored history is printed as well.

    write / set

Write a JMX attribute’s value and print out the value as it is returned from the server. The required arguments are the MBean’s name, the attribute and the value to set. Optionally, a inner path can be provided as well in which case a inner value is set. The MBean’s name and the attribute can be substituted by an alias name, too. See also aliases for getting all available aliases.

The old value of the attribute (or the object pointed to by the inner path) is printed out in the same as for read

To set a null value use [null] as argument, to set an empty string use an empty argument (i.e. "" on the command line). These values are interpreted special, so you can’t use them literally as values.

If the option --history is given and history tracking is switched on (see below), then the stored history is printed as well.

    exec / call

Execute a JMX operation. The required arguments are the MBean’s name, the name of the operation to execute and the arguments required for this operations (which can be empty if the operation doesn’t take any arguments). The return value is the return value of the operation which can be undef in the case of a void operation.

A operation alias can also be used for the MBean’s name and operation.

To use a null argument use [null], to set an empty string as argument use an empty argument (i.e. "") on the command line. These values are interpreted special, so you can’t use them literally as values.

For a single return value, the value itself is printed (without additional newline), for a more complex data structure, Data::Dumper is used.

If the option --history is given and history tracking is switched on (see below), then the stored history is printed as well.


Print out all known aliases. See JMX::Jmx4Perl::Manual for a discussion about aliases. In short, you can use an alias as a shortcut for an MBean’s and attribute’s name.


Search for a certain MBean. As argument you should provide a pattern like *:j2eeType=Servlet,*. I.e you can use the wildcard * for the domain name part, and properties as a whole (but not within a key=property tuple). See <> for a complete explanation of how a pattern can look like. As a result of this operation, a list of fully qualified MBean names is printed out line by line which match the given pattern.


Encrypt a given password so that it can be stored in its encrypted form in a configuration file. Please note, that this is by no means secure and only usual to avoid casual discovery of the password. Since jmx4perl acts as a client it needs to be able to decrypt the password on its own when contacting the agent, so it is a simple symmetric encryptions. The password printed out can be used as Password value for HTTP authentication and HTTP proxy authentication in configuration files or at the command line.


The agent knows about a history mode, which can remember a certain amount return values from previous requests. This mode can be switched on/off on a per attribute (+ inner path) and operation basis. By default it is switched off completely. You can switch in on by executing the JMX4PERL_HISTORY_MAX_ATTRIBUTE and JMX4PERL_HISTORY_MAX_OPERATION operation with exec commands. This is best explained by some example:

 jmx4perl exec JMX4PERL_HISTORY_MAX_ATTRIBUTE java.lang:type=Memory HeapMemoryUsage used 10 <agent-url>

This switches on tracking of this particular attribute. I.e. each time a read request is performed, the value is remembered along with a timestamp on the server side. At maximum 10 entries are kept, the oldest entries get shifted out after the eleventh read. Setting the value to 0 will remove the history completely. You can’t set the limit beyond a certain hard limit, which can be found as attribute under the alias JMX4PERL_HISTORY_MAX_ENTRIES. Unfortunately, one can not use an alias yet for the arguments of JMX4PERL_HISTORY_MAX_ATTRIBUTE. Also note, if you don’t has an inner path, you need to use a [null] as the argument before the max entry number.

For completely resetting the history, use

 jmx4perl exec JMX4PERL_HISTORY_RESET <agent-url>

If you are curious about the size of the history for all entries, use

 jmx4perl read JMX4PERL_HISTORY_SIZE <agent-url>

This will print out the history size in bytes.


JMX::Jmx4Perl - Entry point for programmatic JMX access which is used by this tool.

check_jmx4perl - a production ready Nagios check using JMX::Jmx4Perl

jolokia - utility for downloading and managing Jolokia agents

j4psh - readline based JMX shell with context sensitive command line completion.


This file is part of jmx4perl.

Jmx4perl is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 2 of the License, or (at your option) any later version.

jmx4perl is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with jmx4perl. If not, see <>.

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