xuyuji9000/linux-playground

linux-playground

Approaches of learning

• Derive questions from execution, and try to find a answer to the question.

  Q: What is the boundry of digging into one topic?

  A: Do not have a clear answer yet, accumulated following steps for use for now:

  • Dig one level deeper to answer concerned topic

  • For questions deeper than the immediate lower level, understand the concepts and let go.

  The reasoning here is that, there is no repeated environment to sustain the knowledge.

Historical development of operating system

Learning history helps with understanding why.

• Operating Systems: Crash Course Computer Science #18

  This video gives historical introduction of the development of operating system.

Data analysis

• kernel-analysis

Learning kernel

• execve()

  This system call is used for program loading

• Build Linux kernel and module

• Annotate net_device data structure

• Read Linux source code book

  • Understanding the Linux Kernel

    Reading Notes

  • Understanding Linux Network Internals

  • Linux Device Drivers, Third Edition

• ELF format

• netlink

  Document kernel netlink learning here

• wireguard

• loopback

  This file annotates the loopback interface source code.

• net_device

• frame-reception

Filesystem

• An introduction to Linux filesystems

User Space

• user space command lines

  Try to organize Linux user space command lines related learning here.

Linux administration

• Go through Linux admin tutorial

linux-playground's Issues

Use raspberry pi as network gateway.

Reference

• How to install OpenWrt on Raspberry Pi
  Listen to speechify.
  Install Openwrt on raspberry pi.

• How to Make a Flowchart in Apple Keynote - Video Tutorial
  Diagram prepared on the macos keynote

• 将树莓派打造成旁路由，配置OperWrt，低成本优化网速，还能科学上网
  Openwrt setup through macos.

• #3 树莓派4B做旁路由使用，科学上网
  Mention open-wrt raspberry pi version.

  open-wrt makes the configuration of vpn easier.
  openwrt mentioned in the video is quite old, it's from Nov 21, 2021.
  And the steps mentioned to install openwrt on raspberry pi is not clear.

•  How to Use Raspberry Pi as a VPN Gateway 
  Listen to speechify.
  Setup openvpn with vpn provider certificate.
  China blocks openvpn protocol, so the raspian + openvpn + astrill openvpn certificate approach DOES NOT WORK.

• SuLingGG / OpenWrt-Rpi
  A custom openwrt build.

Dig into Cgroups

Reference

• Chapter 1. Introduction to Control Groups (Cgroups)

Set Dynamic DNS on Raspberry Pi

In the following picture contains a list of potential dynamic DNS services to use.

Reference

• linux-playground/raspberrypi/Setup-Dynamic-DNS.md

How to get status code out of subshell inside backtick

Reference

1. How can I get bash to exit on backtick failure in a similar way to pipefail?

How to prepare raspberry pi as a wifi router

1. Install openwrt on raspberry pi

2. setup wlan

   Configure /etc/config/wireless

3. Use shadowsocks server list

Reference

• Use raspberry pi as network gateway

  One previous raspberry pi related issue reference

• Turn your Raspberry Pi into a WiFi Router using OpenWrt

  This article contains openwrt wifi access point configuration.

• #3 树莓派4B做旁路由使用，科学上网

  Reference this video for custom built openwrt firmware installation

• 固件下载

  Reference this page for custom build openwrt firmwares.

Centos setup process on virtualbox

Have better understanding of 'flush' or 'fsync' from sqlite related to linux file system

fsnyc transfers all modified in-core data of (i.e., modified buffer cache pages for) the file referred to by the file descriptor fd to the disk device so that all changed information can be retrieved even if the system crashes or is rebooted.

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page cache, a transparent cache for the pages originating from a secondary storage device such as a hard disk drive(HDD)

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page is a fixed length contiguous block of virtual memory, described in a single entry in page table.

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Why Virtual Memory?

• Free application from having to manage shared memory space

• increased security, due to memory isolation

• Being able to conceptually use more memory than might be physically available, using the technique of paging

Loop through file lines

while IFS= read -r line
do
   ## take some action on $line
  echo "$line"
done < <(cat ./file.txt)

Centos setup process on virtualbox