Quartz 4

Recent Notes

PS & Top

3 min read

Process: Set of instructions loaded in a memory

CommandAction
ps xShow all of your running processes.
ps axShow all processes on the system, not just the ones you own
ps uInclude more detailed information on processes.
ps wShow full command names, not just what fits on one line

ps a: All terminals

ps e: List of all processes

ps o: Custom properties

ps ef: List of all processes in all TTYs

OUTPUT MEANING

  • Top output

    PR: Priority

    NI: Nice

    VIRT: Virtual memory

    RES: Physical memory

    SHR: Shared memory

    S: State

    TIME: Total timefo

    PPID: Parent PID

    C: CPU

    STIME: Start time

To start a job in background, type & at the end of the command and then use disown to disconnect the job from the terminal. To put a foreground job to background, Ctrl+Z, bg and disown.

Process Stats

STAT or S

  • D-uninterruptible sleep (usually IO error): If a process can’t access to the system (overload, IO error, poor RAM etc.) it makes its stat D.

  • R-running: This is a state where a process is either in running or ready to run

  • S-interruptible sleep: Waiting for an event to complete. Bildigimiz sleep iste

  • T-stopped: Once the process is completed, this state occurs. This process can be restarted.

  • Z-defunct(zombie): In this state, the process will be terminated and the information will still be available in the process table. (For example A process is the parent of B process and B process is used by some application. If A process is killed, normally B would also be killed but because its used by some app, it will go to state Z) A zombie process is a process whose execution is completed but it still has an entry in the process table

  • W-paging: Moving in or out of swap (page in - page out)

  • More state

    < high-priority (not nice to other users)
N low-priority (nice to other users)
L has pages locked into memory (for real-time and custom IO)
s is a session leader
l is multi-threaded (using CLONE_THREAD, like NPTL pthreads do)
+ is in the foreground process group

PS Custom

tty,comm,pid,nice,%mem,%cpu

Nice

Nice is the priority of the process. -20 to 19. -20 means it is the highest priority

renice: Change the nice value of process

NOTE: If TTY value is ? then it means that process isn’t started by a user. It is system or kernel process

  • Priority ve nice

    Nice value is a user-space and priority PR is the process’s actual priority that use by Linux kernel. In linux system priorities are 0 to 139 in which 0 to 99 for real time and 100 to 139 for users. nice value range is -20 to +19 where -20 is highest, 0 default and +19 is lowest. relation between nice value and priority is : PR = NI + 20

fg: Foreground last process

bg: Background last process

%1: Job 1

Graph View

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