jinfo

jinfo [ option ] pid

-flags
    Prints the JVM flags that were used to start the process. Includes both standard and non-standard flags.

-sysprops
    Prints the Java system properties of the process.

-vmargs
    Prints the JVM arguments passed to the process (e.g., -Xmx, -Dproperty=value).

-h | -help
    Displays help message.

pid
    The process ID of the Java process to connect to. You can find this using commands like jps.

-F
    Forces use of the attach mechanism when the target process does not respond. Use with caution.

The jinfo command is a utility that retrieves configuration information from a running Java Virtual Machine (JVM). It can be used to examine system properties, JVM arguments, and flags used to start the JVM process. This information is crucial for diagnosing performance issues, understanding JVM behavior, and verifying that the JVM is running with the expected settings.
jinfo connects to the target JVM using the Attach API, enabling it to dynamically inspect the JVM's state without restarting it. The output of jinfo provides valuable insights into the JVM's configuration, including memory settings, garbage collection algorithms, and other critical parameters. Analyzing this information helps optimize the JVM's performance and troubleshoot runtime issues effectively. It's especially useful in production environments for observing JVM settings without disrupting the running application.
jinfo requires appropriate permissions to access the JVM process and might require the JVM to be running under the same user account. The available options for jinfo allow retrieving different types of information from the JVM.

jinfo requires the Attach API to be enabled in the target JVM. The JVM must be running under the same user, or jinfo must be run with appropriate privileges. The `-F` option should be used carefully, as it might lead to instability if the target JVM is in a critical state.

Accessing sensitive JVM configuration information requires appropriate permissions. Ensure that the user running jinfo has the necessary privileges to access the target JVM process. Restricting access to these details helps prevent unauthorized access to potentially sensitive system and application settings.

If jinfo fails to connect to the target JVM, ensure that the Attach API is enabled and that the JVM is running under the same user account, or with sufficient privileges. Check the JVM's command-line arguments and system properties for any configuration that might be preventing remote access. Using the `-F` option might resolve connection issues, but should be used as a last resort.

jinfo has been a part of the Java Development Kit (JDK) for many years. It was introduced as a tool for inspecting the configuration of running JVMs. The command's functionality has remained relatively stable over time, primarily focused on retrieving JVM flags, system properties, and arguments. It has proven to be an invaluable tool for developers and system administrators for diagnosing issues and understanding JVM behavior.

jps(1), jstat(1), jstack(1), jmap(1)