Getting Information About a Process

The method Process.pid returns the native process ID of the process. The method Process.info returns a ProcessHandle.Info instance, which contains additional information about the process, such as its executable path name, start time, and user.

In the following excerpt, the method getInfoTest starts a process and then prints information about it:

    public static void getInfoTest() throws IOException {
        ProcessBuilder pb = new ProcessBuilder("echo", "Hello World!");
        String na = "<not available>";
        Process p = pb.start();
        ProcessHandle.Info info = p.info();
        System.out.printf("Process ID: %s%n", p.pid());
        System.out.printf("Command name: %s%n", info.command().orElse(na));
        System.out.printf("Command line: %s%n", info.commandLine().orElse(na));

        System.out.printf("Start time: %s%n",
            info.startInstant().map((Instant i) -> i
                .atZone(ZoneId.systemDefault()).toLocalDateTime().toString())
                .orElse(na));

        System.out.printf("Arguments: %s%n",
            info.arguments().map(
                (String[] a) -> Stream.of(a).collect(Collectors.joining(" ")))
                .orElse(na));

        System.out.printf("User: %s%n", info.user().orElse(na));
    }

This method prints output similar to the following:

Process ID: 18761
Command name: /usr/bin/echo
Command line: echo Hello World!
Start time: 2017-05-30T18:52:15.577
Arguments: <not available>
User: administrator

Note:

• The attributes of a process vary by operating system and are not available in all implementations. In addition, information about processes is limited by the operating system privileges of the process making the request.

• All the methods in the interface ProcessHandle.Info return instances of Optional<T>; always check if the returned value is empty.