The //**top**// command in Linux and Unix-like systems like FreeBSD is used to display real-time information about the system's processes, including the CPU and memory usage, process IDs, and other system statistics. It provides an interactive, scrolling view of the processes running on a system, sorted by the amount of system resources they are using.

Here are a few examples of how the **top** command can be used in //**Linux**// and //**FreeBSD**//:

  - Display real-time information about system processes: **top**
  - Display real-time information about a specific process by its PID : **top -p PID** 
  - in Linux sort the process by memory usage instead of CPU usage : **top -o %MEM**
  - in FreeBSD sort the process by memory usage instead of CPU usage : **top -o size**
  - Display real-time information about all processes and threads: **top -H**

The **top** command without any options will display real-time information about all processes running on the system, sorted by the percentage of CPU usage. The **-p** option can be used to display real-time information about a specific process by its PID. The **-o** option can be used to sort the process by memory usage instead of CPU usage. The **-H** option can be used to display real-time information about all processes and threads running on the system


Please note that the options for **top** command //may vary// depending on the version of //**Linux**// or //**FreeBSD**// installed. Please review the man pages for more options.

**Top** command is very useful for monitoring the performance of the system, it's widely used by system administrators for troubleshooting and performance tuning