jcmd
Sends diagnostic command requests to a running Java Virtual Machine.
Synopsis
jcmd [ options ]
jcmd [ pid | main-class ] PerfCounter.print
jcmd [ pid | main-class ] command [ arguments ]
jcmd [ pid | main-class ] -f file
- options
-
The command-line options. See Options.
- pid
-
Identifies the process that receives the diagnostic command requests. The process must be a Java process. To get a list of Java processes running on a machine, use jps(1) or jcmd(1).
- main-class
-
The main class of the process that receives the diagnostic command requests. When matching processes, any process whose main class name contains the specified string as a substring is matched. If several running Java processes share the same main class, then the diagnostic command request is sent to all these processes. To get a list of Java processes running on a machine, use jps(1) or jcmd(1).
- command [arguments]
-
The main class of the process that receives the diagnostic command requests. When matching processes, any process whose main class name contains the specified string as a substring is matched. If several running Java processes share the same main class, then the diagnostic command request is sent to all these processes. To get a list of Java processes running on a machine, use jps(1) or jcmd(1).
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).For example, suppose you want to send a diagnostic command request to
com.example.MyClass name="Value of name argument". The following three commands are valid:jcmd com.example.MyClass name=\"Value of name argument\" jcmd com.example.MyClass name="'Value of name argument'" jcmd com.example.MyClass name='"Value of name argument"'
The following two commands are not valid:
jcmd com.example.MyClass name=Value\\ of\\ name\\ argument jcmd com.example.MyClass name="Value\ of\ name\ argument"
- Perfcounter.print
-
Print the performance counters available on the targeted Java processes. The list of performance counters might vary with the Java process.
- -f file
-
Read commands from file and call them on the targeted Java processes. In file, each command must be written on a single line. Lines starting with # are ignored. Processing of file ends when all lines have been called or when a line containing the
stopkeyword is read.
Description
jcmd is a utility to send diagnostic command requests to a Java Virtual Machine supporting this feature.
Used without arguments or with the -l option, jcmd prints the list of running Java processes with their process ID, their main class and their command-line arguments.
When a process ID is specified on the command line, jcmd sends the diagnostic command request to the process with this ID.
When a main class is specified on the command line, jcmd sends the diagnostic command request to all Java processes for which the command-line argument is a substring of the Java process' main class.
With the PerfCounter.print argument, jcmd prints the performance counters available on the targeted Java processes.
With the -f option, jcmd sends to the targeted Java processes the diagnostic commands stored in the specified file.
Options
Options are mutually exclusive. Options, when used, must immediately follow the command name.
- -l
-
Prints the list of running Java processes with their process IDs, their main classes, and their command-line arguments.
- -h
-
Prints a help message.
- -help
-
Prints a help message.