A process is an executing program.
Unix was designed from the beginning to handle multiple processes.
Linux follows this excellent tradition.
The operating system gives users and particularly the root user control over processes.
Let's take a closer look at processes and what they mean to users.
The kernel is the part of the Linux operating system that handles system management.
It is not accessible to ordinary users.
You may run Damn Small Linux as the root user and learn how the kernel works.
When you have demonstrated your mastery of system concepts you may be given permission to apply your knowledge on larger Linux systems.
Part of the kernel's work is managing processes.
There are basically four such functions: controlling process execution, allocating memory for processes, scheduling processes, and managing resource access for processes.
Let's look briefly at each function.
The kernel creates, terminates, and coordinates processes.
The root user and sometimes a regular user have access to these functions.
It is possible to terminate a haywire process, one for example that has taken over the computer virtually blocking other processes.
The kernel allocates memory for processes.
Root users and their authorized agents may review statistics on memory usage and improve system performance.
Scheduling and resource access are very important to maximize system performance and minimizing user waiting times.
Knowledge of how processes work and what is really happening in a busy system can improve system performance and user satisfaction.
Sometimes it isn't necessary to spend a penny to improve performance.
There is room in the marketplace for specialists in Linux scheduling and resource management.
You cannot become such a specialist overnight but you can start by learning the tools with Damn Small Linux.
A given process is identified by a process number.
During the course of system execution processes terminate, by themselves or because some one shut them down.
Over time other processes are created.
The process number always increases until the system is restarted.
Some processes are system processes; they are part of the overhead in running a system.
They work behind the scenes.
Other processes are user processes, doing the work that users actually want.
The ps command provides information on running processes.
For example, it may provide the name of the user associated with the process, the process identifier, the identifier of the father process (the one that created - the technical word is spawned) the given process, when the process was spawned and other information that may help manage a busy system.
I think that you can guess what the kill command does.
It has several options, for example, some haywire processes are more difficult to remove than others.
Our next subjects are Linux shells and utilities.