How to use the command 'jps' (with examples)
The ‘jps’ command is a Java Tool that displays the status of all Java Virtual Machine (JVM) processes running on the current user’s system. It is a useful command for identifying and monitoring Java processes.
Use case 1: List all JVM processes
Code:
jps
Motivation: You may want to see a list of all JVM processes running on your machine. This can be useful for monitoring purposes or to identify any Java processes that may be consuming excessive resources.
Explanation: By simply running the ‘jps’ command without any arguments, it will list all JVM processes along with their corresponding process IDs (PIDs) and the names of the Java processes.
Example output:
12345 ExampleProcess
67890 AnotherProcess
Use case 2: List all JVM processes with only PID
Code:
jps -q
Motivation: Sometimes, you may only need the process IDs (PIDs) of the JVM processes without the process names. This can be useful for scripting purposes or for passing the process IDs to other commands.
Explanation: By adding the ‘-q’ option to the ‘jps’ command, it will only list the PIDs of all JVM processes, excluding the process names.
Example output:
12345
67890
Use case 3: Display the arguments passed to the processes
Code:
jps -m
Motivation: When troubleshooting Java processes or analyzing their behavior, it can be helpful to view the arguments passed to each process.
Explanation: Adding the ‘-m’ option to the ‘jps’ command will display the arguments passed to the JVM processes. This includes any command-line arguments or system properties specified when starting the Java process.
Example output:
12345 ExampleProcess -Djava.library.path=/path/to/lib
67890 AnotherProcess
Use case 4: Display the full package name of all processes
Code:
jps -l
Motivation: In some cases, you may want to see the full package name of the Java processes rather than just the process names. This can be useful when multiple processes have the same name but belong to different packages.
Explanation: By using the ‘-l’ option, the ‘jps’ command will display the full package name of all JVM processes in addition to their process IDs and names.
Example output:
12345 com.example.ExampleProcess
67890 com.anotherprocess.AnotherProcess
Use case 5: Display the arguments passed to the JVM
Code:
jps -v
Motivation: Similar to use case 3, displaying the arguments passed to the JVM can provide insight into the runtime configuration of a Java process.
Explanation: When running the ‘jps’ command with the ‘-v’ option, it will show the arguments passed to the JVM itself, including the JVM options and system properties.
Example output:
12345 -Dsome.property=value -Xmx512m ExampleProcess
67890 AnotherProcess
Conclusion:
The ‘jps’ command is a powerful tool for monitoring and managing Java processes on a system. By utilizing its various options, you can gather valuable information about the Java processes, such as their process IDs, names, arguments, and package names. This can greatly aid in troubleshooting, resource management, and profiling of Java applications.
