LFS201 - Chapter 2 Discussion // Questions // Banter

blackbear710

I will try to make a thread for each chapter at some point, it will have the same title throughout the course

I am relatively new to Linux but I thought Chapter 2 was fairly straight forward in regards to the File System Hierarchy

A question for anyone who uses Linux Professionally...

Is there a few particular File Systems it would be better to know like the back of my hand: bin, lib, etc, root, dev, etc.... that is used more vs others, or does it really just depend on the job you have?

blackbear710

@luisviveropena ^ ?

luisviveropena

Hi @blackbear710 ,

I will try to make a thread for each chapter at some point, it will have the same title throughout the course

If you want to do that, I don't see any problem.

Is there a few particular File Systems it would be better to know like the back of my hand:
bin, lib, etc, root, dev, etc.... that is used more vs others, or does it really just depend on the job you have?

I don't think so. A system administrator, operator, etc., uses and/or work with what he/she needs at the moment. So we use to work mostly with tools (binaries) located in some direcories you can find in the path. For example:

root@starseedstation:~# echo $PATH
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin

Many regards!
Luis.

Warren67

A thread for every chapter is the best idea! I was reading through so much info to see if Lab 4.1 was already asked about. Lab 4.1 seems 100x harder than everything else I read through. I don't understand the questions or solution, even using the legend. Also, by study plan of getting through this course of 44 chapters in 4 weeks, does that not mean 11 chapters per week?

Best regards,
Warren

fcioanca

You can use key words in the search bar for the forumto see if a question was asked on specific topics. This will make it much easier.

Warren67

Thanks for the tip! No luck with the 201 lab so i guess not asked yet.

fcioanca

@Warren67 One other tip for courses - each course has their own forum. And there are a lot of questions and answers in there. You can always go search in the specific course forum, and that is an additional resource for you to use as well, besides the bootcamp forum.

Warren67

Same results, everybody from every year, finds it super easy but me, lol. i will watch zoom next week.

chrisfeig

@Warren67 said:
A thread for every chapter is the best idea! I was reading through so much info to see if Lab 4.1 was already asked about. Lab 4.1 seems 100x harder than everything else I read through. I don't understand the questions or solution, even using the legend. Also, by study plan of getting through this course of 44 chapters in 4 weeks, does that not mean 11 chapters per week?

Best regards,
Warren

@Warren67 yes I have my eye on the study plan's suggested timing also. Not so much as a schedule but as a guide to how much time to spend on each chapter and how deep to go into each topic.

So on the basis of completing everything in 6 months, the study plan suggests 4 weeks for LFS201 which is 44 chapters. This could be up to 8 weeks if completing over a year. 44 chapters in 4-8 weeks is equivalent to spending 0.5-1 day / chapter.

At the moment, I'm spending more than this on each chapter in LFS201. I'm finding the content easy to get through, and some of the labs are also very basic, but then some are quite challenging are require a thorough read of the man pages and what seems like a deep dive for example into process and signal theory in Chapter 4.

dacarab

@Warren67 said:
A thread for every chapter is the best idea! I was reading through so much info to see if Lab 4.1 was already asked about. Lab 4.1 seems 100x harder than everything else I read through. I don't understand the questions or solution, even using the legend. Also, by study plan of getting through this course of 44 chapters in 4 weeks, does that not mean 11 chapters per week?

Best regards,
Warren

Hi Warren,

Here are my takeaways from Lab 4.1 - please note this is just my interpretation and hence potentially incorrect in some way. Apologies, this went a bit longer that I'd intended. The "Note the following" section towards the bottom of the lab covers the key takeaways from the lab:

If more than one of a given signal is raised while the process has blocked it, does the process receive it multiple times?

Does the behaviour of real time signals differ from normal signals?

If you run the program, you should see in the Signal Number(Times Processed) section that signals with an ID of 34+ (the real time signals) are handled by the process 3 times each, implying each instance of these signals when sent (lines 99 - 117) is queued until the process can receive them (receiving signals is blocked by the process at line 90, and unblocked at line 121).

Whereas the signals with an ID of 31 and below are only handled once - implying that they are not queued as such, just the fact that one or more signals of a particular id was sent is stored by the system (signal is either ON or OFF). This info is then passed to the process once it can receive signals.

Are all signals received by the process, or are some handled before they reach it?

For me when running the program, looking through the Signal Number(Times Processed) section of the output, I see that signals 9, 18, 19, 32 & 33 are not received.

Signal 18 (SIGCONT) looks like it's handled by the shell to resume a process that has been previously paused - so it makes sense that this signal doesn't reach the process.

Signals 9, 19, 32 and 33 are not sent (lines 100 - 102). My interpretation of this being that the program creator expects these signals to be problematic. The note at the bottom of the lab explains why 32 & 33 could be an issue. My understanding of signals 9 (SIGKILL) and 19 (SIGSTOP) is that a process cannot override the default signal handlers for these - so if the process were to send these to itself, it would fail to run correctly.

What order are the signals received in?

Looking through lines 99 to 117 of the code again, the signals were sent sequentially (1..64)

Looking through the final section of the program output, History: Signal Number(Count Processed) shows the order in which the signals were received. For me, signals 31 and below (the non-realtime signals) are not received in a sequential order.

However, signals 34+ (the realtime ones) are received sequentially - which again implies that realtime signals are queued by the system and are handled first in first out, whereas the other signals are handled in some other fashion.

Hope that is helpful and not too waffle-y, there may well be other takeaways that I've missed..

Cheers

Warren67

Thanks dacarab, I am gaining a lot by going through your thoughts on this lab. Also read a few chapters of the "The Linux Command Line" to get a new take, my work on LFS101 was rushed and i had gaps in understanding basics.

Regards

Warren67

@Chrisfeig, The pace is my biggest challenge, glad you clarified it as i thought i was misreading something. I am taking less notes and putting main ideas and problems on flashcards. If i can't recall what the idea means or the solution, I put the solution on the back and revisit until i know it cold.

chrisfeig

@Warren67 said:
@Chrisfeig, The pace is my biggest challenge, glad you clarified it as i thought i was misreading something. I am taking less notes and putting main ideas and problems on flashcards. If i can't recall what the idea means or the solution, I put the solution on the back and revisit until i know it cold.

Flashcards are a great idea @Warren67 I use Anki if you haven't tried it yet I highly recommend it The spaced repetition system is brilliant.

Warren67

I haven't seen Anki in years. Had to Google it. Installing now.