Recently I took a course on Linux command line and shell scripting, below are the notes I took which I decided to write into a blog to refer to for future reference (there's no way I could remember all of this in a single sitting) 1. Kernel vs Shell OS has 3 layers: Application layer - User apps, Daemons Shell - Command line interface. Kernel - Hardware management, memory management, I/O Handler, CPU, process management. Closest layer to the hardware The kernel controls and mediates access to hardware, for example, it schedules and allocates system resources like memory, CPU, disk etc. The shell works as an interface to access the services provided by the OS. We can further breakdown the layers into the following: User space - If you run a for loop etc, you are in user space. But when you want to perform an operation such as, write to the disk, for example, save a file, then it needs to talk to the kernel space. As the application can't directly talk to the hardware. Kernel sp...