jcmd Man page

jcmd Troubleshooting Tools jcmd

NAME

jcmd – Sends diagnostic command requests to a running Java Virtual
Machine (JVM).

SYNOPSIS

jcmd [-l|-h|-help]

jcmd pid|main-class PerfCounter.print

jcmd pid|main-class -f filename

jcmd pid|main-class command[ arguments]

DESCRIPTION

The jcmd utility is used to send diagnostic command requests to the
JVM. It must be used on the same machine on which the JVM is running,
and have the same effective user and group identifiers that were used
to launch the JVM.

Note
┌────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┐
│ │
│ To invoke diagnostic │
│ commands from a remote │
│ machine or with different │
│ identifiers, you can use the │
│ com.sun.management.DiagnosticCommandMBean │
│ interface. For more │
│ information about the │
│ DiagnosticCommandMBean │
│ interface, see the API │
│ documentation at │
│ http://docs.oracle.com/javase/8/docs/jre/api/management/extension/com/sun/management/DiagnosticCommandMBean.html │
└────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────────┘

If you run jcmd without arguments or with the -l option, it prints the
list of running Java process identifiers with the main class and
command-line arguments that were used to launch the process. Running
jcmd with the -h or -help option prints the tool’s help message.

If you specify the processes identifier (pid) or the main class
(main-class) as the first argument, jcmd sends the diagnostic command
request to the Java process with the specified identifier or to all
Java processes with the specified name of the main class. You can also
send the diagnostic command request to all available Java processes by
specifying 0 as the process identifier. Use one of the following as the
diagnostic command request:

Perfcounter.print
Prints the performance counters available for the specified Java
process. The list of performance counters might vary with the Java
process.

-f filename
The name of the file from which to read diagnostic commands and
send them to the specified Java process. Used only with the -f
option. Each command in the file must be written on a single line.
Lines starting with a number sign (#) are ignored. Processing of
the file ends when all lines have been read or when a line
containing the stop keyword is read.

command [arguments] The command to be sent to the specified Java process. The list of
available diagnostic commands for a given process can be obtained
by sending the help command to this process. Each diagnostic
command has its own set of arguments. To see the description,
syntax, and a list of available arguments for a command, use the
name of the command as the argument for the help command.

Note: If any arguments contain spaces, you must surround them with
single or double quotation marks (‘ or “). In addition, you must
escape single or double quotation marks with a backslash (\) to
prevent the operating system shell from processing quotation marks.
Alternatively, you can surround these arguments with single
quotation marks and then with double quotation marks (or with
double quotation marks and then with single quotation marks).

OPTIONS

Options are mutually exclusive.

-f filename
Reads commands from the specified file. This option can be used
only if you specify the process identifier or the main class as the
first argument. Each command in the file must be written on a
single line. Lines starting with a number sign (#) are ignored.
Processing of the file ends when all lines have been read or when a
line containing the stop keyword is read.

-h
-help
Prints a help message.

-l
Prints the list of running Java processes identifiers with the main
class and command-line arguments.

SEE ALSO

· jps

JDK 8 03 March 2015 jcmd