258 CHAPTER 16 TAKING CONTROL OF THE (Web hosting packages)
258 CHAPTER 16 TAKING CONTROL OF THE SYSTEM Figure 16-1. The top program gives you an eagle-eye view of the processes running on your system. Here s an example of a line taken from top on my test PC, shown with the column headings from the process list: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 5499 root 15 0 78052 25m 60m S 2.3 5.0 6:11.72 Xorg A lot of information is presented here, as described in Table 16-1. Table 16-1. The top Program Process Information Column Description PID The first number is the process ID (PID). This is the unique number that the system uses to track the process. The PID comes in handy if you want to kill (terminate) the process (as explained in the next section of this chapter). USER This column lists the owner of the particular process. As with files, all processes must have an owner. A lot of processes will appear to be owned by the root user. Some of them are system processes that need to access the system hardware, which is something only the root user is allowed to do. Other processes are owned by root for protection; root ownership means that ordinary users cannot tamper with these processes. PR This column shows the priority of the process. This is a dynamic number, showing where the particular process is in the CPU queue at the present time.