Linux has become not the last player in the operating system market, having earned a reputation as a fairly strong OS that is used by many people. In this article, we will check the types of processes in Linux. Let’s get it started!
Operating System Explained
Before we dive into the topic, we first need to understand what the process is in terms of this Operating System. The process in this case is an object of the Linux operating system and is essentially a running program or service. Each running process, in turn, can run additional processes on Linux. There are so-called parental and child processes. Proditelskymi are those processes that have created a new process.
A new process in relation to the previously created process is called appropriate. Processes in Linux OS are part of the operating system and act as tasks The work program includes one or more processes. The task consists of one or more programs, which in turn run as a command processor. Each process in this operating system is characterized by a certain set of attributes. Here are some features that describe the list of running linux processes:
- So the first is Parent Process Identifier, abbreviated (PRID). This attribute receives the process at startup and is used to obtain the status of the parent process.
- Next is the Process Identifier (PID). Each new process started gets a number and one bigger than the previous one. And each process in the system has a unique identifier.
- There are also attributes called real and effective user IDs. These attributes of the process on the affiliation of not only the process to a particular user but also to the group. Effective identifiers match the identifiers of the user on whose behalf the process was started. Real identifiers should be used to manage the process. It is a great option to check running processes linux to increase your personal or business performance.
All identifiers are passed from the parent to the child process, respectively. In addition, in the Linux operating system, each process must be in a certain state and can also be transferred by the system or user commands from one state to another. Here is what you should know about these states:
- Task Stopped means that the process is suspended. Any process can be stopped. This can be done by both the system and the user. The state of this process is indicated by the letter T.
- Task Running is denoted by the symbol R, and means that the process is ready to run or still running. Task Interruptiple is a waiting process, denoted by the letter S and means that the process has initialized the execution of any system operation and is waiting for its completion.
- Task Uninterruptible-continuous process. In this state, the processes are waiting for the completion of the I / O operation with direct access to memory. This type of process cannot be completed until the I / O operation is completed. They are denoted by the letter D.
The Varierty of Linux Processes
Now we can finally look at the types of processes in Linux. So there are different types of processes in Linux with their own benefits for end users.
The first type is system processes. They are part of the kernel and are located in RAM. They do not have corresponding programs in the form of executable files and run when the kernel is initialized. Data from such processes is at the core of the system and thus access data that is not available to other processes. System processes are, for example, paging manager, kernel memory manager. Application processes or user processes. Application processes include other processes running on the system. Linux listing processes are also present in this OS. Typically, these are processes that are part of a user session.
The most important application process is the shell, which ensures your work in the Linux operating system. Processes of this type can be used in the background, but in any case the time of their session is limited by the user’s session. If you log out, all application processes are automatically destroyed.
There are also so-called zombie processes and orphan processes. Zombie processes occur when the parent process continues to work without waiting for the end of the session of the child process. Processes of this type are denoted by the letter Z.
Another process can become a zombie process if the parent process is stopped or destroyed by the child process. Accordingly, the child process becomes an orphan process, so to speak. And the process of initialization in this case becomes the parent process becoming it. If the child process terminates its session and the parent process does not receive completion status, then the child process becomes a zombie process.
There is also the so-called demon process, or demonic process. Such processes are non-interactive and run in the usual way, i.e. by downloading the appropriate programs running in the background. They are not associated with any user session and cannot be directly managed or controlled by the user. For the most part, these processes wait for a process to request a service, such as access to a file archive or print a document. They are triggered by service requests from other processes and do not need a control terminal.
There are two main processes-daemon in Linux: c
- Crond — it performs tasks in the background and acts as a task scheduler;
- httpd — this is a web server daemon process.
The process can be started in two ways: in the foreground process, and in the background process. Consider each of them. The first way is when the default user performs the process in the foreground. It receives input from the command line and displays it on the computer screen. An important nuance, if the process is running in the foreground, the terminal will automatically prevent the initiation of a new process until the existing process is completed.
Last but not list important, processes of this type do not require keyboard input. Another process can be run from the terminal while the previous one is running in the background. From the terminal, you can also switch between foreground and background processes.
The more you are aware of different types of processes in Linux, the more intuitive and professional user of the system you will become. It will also help you understand what software and hardware will be necessary to expand your network’s capacity in the future.