Today, I’m reading cpu.land blog about how computers run the program. I’m re-reading it actually. That is going good so far. In the previous read, I couldn’t grasp a few things. It could be because I don’t know much and I’ve read it on phone so I couldn’t explore much.

This time I’ve already explored few things with the question like how ls works. Thanks to GPT, it helped a lot in my quest.

Essentially, when we type ls in terminal and press enter,

• shell parses the command
• finds the binary
• uses syscall to interact with kernel to create a child process
• child process replaces itself with the loaded binary program
• then ls runs and uses syscalls to get the necessary data and other ops
• it prints to the terminal
• it exits
• control comes back to the shell
• we got the shell prompt again
• voila!

In my quest I used tools like otool, lldb (I guess) to mess up with things. I’ve also found a nice reverse engineering guide from a github.io website that I’ve linked in my LIIL page.

So many things, software interrupts, hardware interrupts, userland, kernel, registers, mmu, virtual memory, paging, security rings, there is a lot of interesting things.

Now back to reading THE BOOK!

I’ve read about C++ based sorting techniques that are appropriate for pairs, tuples, & structs. And the way to use custom callback functions.

I’ve also learned about auto iteration and structs, pairs & tuples. I’ve skimmed through the binary search part. I’ll go through with full attention tomorrow. Once I did it, I’ll review my progress and fill in the knowlege gaps before moving on to the next chapter.

Stored the learnings at: https://github.com/Maheshkumar-novice/TIL/blob/main/cpp/sorting.cpp