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LFS201 - confusing 3.2 lab

hey everyone,
I just did lab 3.2 and was very confused by how to get from $ ipcs -p to $ ps aux |grep -e 20573 -e 2048. How do we know what process IDs to select? what's the main idea for this exercise?


  • Hey @owenpkent my ten-cents: since it is now LFS201 and not the pre-course, it is somewhat assumed you may or potentially should know what ps, aux, grep, the |(pipe) symbol, and ls does inside the CLI for you Distro?

    From a random website > The /proc file system stores information about currently running processes on your system, it contains directories for each process. (PID) Process ID. I am sure it is somewhere in the Chapters, but just showing how easy it is to find answers to questions on the internet.

    Use the ls command to list its contents, however, the list may be long, so employ a pipeline and the less utility to view the /proc contents in a more convenient way as below >>> ls /proc less or | (pipe)

    From the Lab >> Perform these steps on your system and identify the various resources being used and by who .

    So what Process is running on your system, who is using it, along with some other tid-bits like status and bytes used up?
    Is how I interpret that

    Also, the Internet / Google is your best friend if you don't know an answer to something 9/10, someone has already asked that question, and someone else has answered it, and it has upvotes and the lot with people arguing which answer is best

    What is Grep, What is | , what is -p and aux, what does | do in linux etc.. etc..

    The world is your oyster, and there is so many ways to find answers to questions you may have on ze Internet. I don't use Linux professionally but I assume Linux Admins still reach out to colleagues or the Internet if they don't know something off the top

    I am a novice user myself I would say, with no professional Linux Experience, but I am here to learn and try my best

  • and, I think you can select any process ID you want, the goal is to have you investigate yourself and see what may or may not be running?

  • https://www.tecmint.com/find-process-name-pid-number-linux/ Link for further reading, cause why not

  • also I am sorry if any adds show up on websites that may offend someone, I do not have control over that and was just sighting a url that I had used b4

  • chrisfeig
    chrisfeig Posts: 32

    After spending a day on chapter 3 I was also still finding it hard to understand the logic/purpose of this lab. Unlike a professional setting, we're on a study track here and if we want to get through these courses in 6-12 months there comes a point where it's prudent to put a task aside and move for the sake of progressing through the chapters in a timely manner. This was the case for me with this lab.

    What I got from this lab and the sysvipc(7) man page it is that System V IPC is an old system that uses three mechanisms for communicating between processes: messages queues; semaphores; and shared memory segments.

    By using ipcs and some grep work we can find resources that might have been allocated to IPC but have no processes attached to it, and hence are tied up unnecessarily and could be freed.

  • heiko_s
    heiko_s Posts: 99

    Yep, the chapter and the exercises are a bit confusing. But I agree with Chris.

    Things like memory leaks are quite common. Chapter 3 (at the end) gives us a tool to discover potential memory leaks (nattch = 0 and not marked for destruction) .

    Before my recent PC upgrade from 24Gig to 64Gig, I kept running into out-of-memory issues with Adobe Lightroom on Windows. Obviously Lightroom has problems to free memory, sometimes causing plugins to crash.

    I found this on command line tools to check memory: https://www.howtogeek.com/659529/how-to-check-memory-usage-from-the-linux-terminal/

    Interestingly there is no ipcs.


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