Processes on a Linux System
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Questions and Answers

What is the primary distinction between a program and a process?

  • A program is a running instance of an application, while a process is a file on the hard disk.
  • A program is an executable file on the hard disk, while a process is that executable file running in memory. (correct)
  • A process can exist without a parent process.
  • A program is always stored in the CPU's cache.

    • In process management, what does the term 'PID' refer to?

  • Process Identification Number (correct)
  • Personal ID for user login
  • Process Indicator Device
  • Program Instance Descriptor

    • Which term describes processes that provide essential system and network services and are usually started at system startup?

  • Transient processes
  • Detached processes
  • Daemon processes (correct)
  • User processes

    • What is a child process in relation to its parent process?

    <p>A child process is initiated by a parent process and can also spawn other processes.</p> Signup and view all the answers

    Which term is used to refer to a process that is not associated with a terminal?

    <p>Daemon process</p> Signup and view all the answers

    What does 'PPID' stand for in process management?

    <p>Parent Process Identifier</p> Signup and view all the answers

    When a user starts a process from the terminal, how is that process labeled?

    <p>User process</p> Signup and view all the answers

    What is true about the relationship between parent and child processes?

    <p>Each child process can trace back to a single parent process.</p> Signup and view all the answers

    What does the PPID represent in the output of the ps command?

    <p>Parent Process ID</p> Signup and view all the answers

    What information does the ps --f command primarily provide about each process?

    <p>CPU utilization and process lineage</p> Signup and view all the answers

    Which option can be added to the ps command to include all processes across all terminals?

    <p>--e</p> Signup and view all the answers

    Why are daemon processes not listed in the output of the ps --f command?

    <p>They are not associated with any terminal.</p> Signup and view all the answers

    What is the purpose of using the grep command with the ps command?

    <p>To filter the output for specific information.</p> Signup and view all the answers

    What does the '?' symbol in the TTY column indicate in the process listing?

    <p>The process is a kernel thread or daemon.</p> Signup and view all the answers

    What would the output of the ps command display regarding time if a process ran for less than one second?

    <p>The elapsed time will not be shown.</p> Signup and view all the answers

    Which process typically has a PID of 2 in a Linux environment?

    <p>Kernel Thread Daemon</p> Signup and view all the answers

    What is the PID of the init daemon in a Linux system?

    <p>1</p> Signup and view all the answers

    What represents the Parent Process ID (PPID) of the init daemon?

    <p>0</p> Signup and view all the answers

    Which of the following statements best describes the relationship between processes in Linux?

    <p>Every process can trace back to the init daemon through PPIDs.</p> Signup and view all the answers

    Which command is considered the most versatile for viewing processes in Linux?

    <p>ps</p> Signup and view all the answers

    In a Linux system that uses Systemd for initialization, what will the init process likely appear as?

    <p>systemd</p> Signup and view all the answers

    What is the relationship between Process number 1 and Process number 2?

    <p>Process number 2 has Process number 1 as its parent.</p> Signup and view all the answers

    What does the process state 'R' indicate in the ps command output?

    <p>The process is currently running on the processor.</p> Signup and view all the answers

    Which statement accurately reflects the nature of Linux process IDs (PIDs)?

    <p>PIDs can be reused once a process terminates.</p> Signup and view all the answers

    After logging in to a Linux system, the role of the BASH shell is to:

    <p>Interpret user commands and initiate user processes.</p> Signup and view all the answers

    Which of the following best describes a zombie process?

    <p>A completed process waiting for its parent to release its PID.</p> Signup and view all the answers

    What does the flag 'F' indicate in the output of the ps command?

    <p>The root user started the process.</p> Signup and view all the answers

    Which command is used to view a list of zombie processes in the system?

    <p>ps --el | grep Z</p> Signup and view all the answers

    What does the 'NI' (nice value) affect in a process?

    <p>The way the kernel schedules the process priority.</p> Signup and view all the answers

    How is process priority measured in the Linux kernel?

    <p>Between 0 (high priority) and 127 (low priority).</p> Signup and view all the answers

    What is indicated by a process state of 'D'?

    <p>The process is in an uninterruptible sleep state.</p> Signup and view all the answers

    Which of the following is true about the --l option used with the ps command?

    <p>It provides more information than the --f option.</p> Signup and view all the answers

    Study Notes

    Processes on a Linux System

    • A program is an executable file stored on disk.
    • A process is a program running in memory and on the CPU, essentially a program in action.
    • User processes are programs that run in a terminal, for example: ls, grep, and find.
    • Daemon processes run in the background, typically started at system startup, and provide system services like printing, scheduling, and network services.
    • Every process has a unique Process ID (PID) used by the kernel for identification.
    • Processes can start other processes, known as child processes.
    • Each process has a Parent Process ID (PPID), identifying the process that started it.

    Process Management

    • The init daemon is the first process started by the Linux kernel, with a PID of 1 and a PPID of 0 (referring to the kernel).
    • The init daemon launches most other daemons during system initialization, including those that allow for user logins.
    • After a user logs in, the login program starts a BASH shell, which interprets user commands and starts user processes.
    • The ps command is used to view processes, displaying a list of processes running in the current shell by default.
    • Using the --e option with the ps command shows all processes across terminals and daemons.
    • The --f option with the ps command provides more information about each process, including UID, PPID, STIME, and CPU utilization.
    • The --l option with the ps command displays even more detailed information, including process flags, process state, priority, and nice value.

    Process States

    • The process state (S) column in the ps command output indicates what the process is currently doing.
    • Common states include:
      • S (interruptible sleep): Process is not running on the CPU but is waiting to be awakened by other processes.
      • R (running): Process is currently running on the CPU.
      • D (uninterruptible sleep): Process is waiting for disk access.
      • T (stopped): Process is stopped or being traced by another process.
      • Z (zombie process): Process has finished executing but is waiting for its parent process to release its PID.

    Zombie Processes

    • Zombie processes occur when a process finishes executing but is waiting for its parent process to release its PID.
    • They can accumulate and prevent new processes from being created.
    • Killing the parent process of zombie processes can resolve this issue.

    Process Prioritization

    • Process priority (PRI) is measured between 0 (high priority) and 127 (low priority).
    • Nice value (NI) indirectly affects process priority, measured between -20 (higher chance of high priority) and 19 (higher chance of low priority).

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    Related Documents

    Linux Chapter 9.docx

    Description

    This quiz explores the concepts of programs and processes within a Linux operating system. Learn about user processes, daemon processes, Process IDs (PIDs), and the structure of process management. Understand how the init daemon plays a pivotal role in system initialization.

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