What is the command that should be used to view the process with the process ID value?
IntroductionA Linux server, like any modern computer, runs multiple applications. These are referred to and managed as individual processes. Show
While Linux will handle the low-level, behind-the-scenes management in a process’s life-cycle – i.e., startup, shutdown, memory allocation, and so on – you will need a way of interacting with the operating system to manage them from a higher level. In this guide, you will learn some fundamental aspects of process management. Linux provides a number of standard, built-in tools for this purpose. You will explore these ideas in a Ubuntu 20.04 environment, but any modern Linux distribution will operate in a similar way. Step 1 – How To View Running Processes in LinuxYou can see all of the processes running on your server by using the The first several lines of output provide system statistics, such as CPU/memory load and the total number of running tasks. You can see that there is 1 running process, and 55 processes that are considered to be sleeping because they are not actively using CPU cycles. The remainder of the displayed output shows the running processes and their usage statistics. By default, An improved version of After that, the
In the next section, you’ll learn about how to use tools to query specific processes. Step 2 – How To Use ps to List Processes
Running This output shows all of the processes associated with the current user and terminal session. This makes sense if you are only running the To get a more complete picture of the processes on this system, you can run These options tell By making use of pipes, you can search within the output of This returns both the A quick way of getting the PID of a process is with the The first process spawned at boot, called init, is given the PID of “1”. This process is then responsible for spawning every other process on the system. The later processes are given larger PID numbers. A process’s parent is the process that was responsible for spawning it. Parent processes have a PPID, which you can see in the column headers in many process management applications, including Any communication between the user and the operating system about processes involves translating between process names and PIDs at some point during the operation. This is why these utilities will always include the PID in their output. In the next section, you’ll learn how to use PIDs to send stop, resume, or other signals to running processes. Step 3 – How To Send Processes Signals in LinuxAll processes in Linux respond to signals. Signals are an operating system-level way of telling programs to terminate or modify their behavior. The most common way of passing signals to a program is with the This sends the TERM signal to the process. The TERM signal tells the process to please terminate. This allows the program to perform clean-up operations and exit smoothly. If the program is misbehaving and does not exit when given the TERM signal, you can escalate the signal by passing the This is a special signal that is not sent to the program. Instead, it is given to the operating system kernel, which shuts down the process. This is used to bypass programs that ignore the signals sent to them. Each signal has an associated number that can be passed instead of the name. For instance, You can pass “-15” instead of “-TERM”, and “-9” instead of “-KILL”. Signals are not only used to shut down programs. They can also be used to perform other actions. For instance, many processes that are designed to run
constantly in the background (sometimes called “daemons”) will automatically restart when they are given the The above command will cause Apache to reload its configuration file and resume serving content. Note: Many background processes like this are managed through system services which provide an additional surface for interacting with them, and it is usually
preferable to restart the service itself rather than sending a You can list all of the signals that are possible to send with Although the conventional way of sending signals is through the use of PIDs, there are also methods of doing this with regular process names. The The above command is the equivalent of: If you would like to send a signal to every instance of a certain process, you can use the The above command will send the TERM signal to every instance of Step 4 – How To Adjust Process PrioritiesOften, you will want to adjust which processes are given priority in a server environment. Some processes might be considered mission critical for your situation, while others may be executed whenever there are leftover resources. Linux controls priority through a value called niceness. High priority tasks are considered less nice, because they don’t share resources as well. Low priority processes, on the other hand, are nice because they insist on only taking minimal resources. When you ran Nice values can range between -19/-20 (highest priority) and 19/20 (lowest priority) depending on the system. To run a program with a certain nice value, you can use the This only works when beginning a new program. To alter the nice value of a program that is already executing, you use a tool called ConclusionProcess management is a fundamental part of Linux that is useful in almost every context. Even if you aren’t performing any hands-on system administration, being able to chase down stuck processes and handle them carefully is very helpful. Next, you may want to learn how to
use Which command is used to view process?Using the ps Command. The ps command enables you to check the status of active processes on a system, as well as display technical information about the processes.
How can I see process ID?Task Manager can be opened in a number of ways, but the simplest is to select Ctrl+Alt+Delete, and then select Task Manager. In Windows, first click More details to expand the information displayed. From the Processes tab, select Details to see the process ID listed in the PID column.
Which command gives you the process ID for a running process?You can list running processes using the ps command (ps means process status). The ps command displays your currently running processes in real-time. This will display the process for the current shell with four columns: PID returns the unique process ID.
How do I find the process ID of a process in Linux?A process is nothing but running instance of a program and each process has a unique PID on a Unix-like system. The easiest way to find out if process is running is run ps aux command and grep process name. If you got output along with process name/pid, your process is running.
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