lpi_notes.md

Linux Programming Interface

CHAPTER 2

• Kernel Tasks:

  • Process Schedulling
  • Memory Managment
  • Provision of a file system
  • Creation and termination of processes
  • Access to devices
  • Networking
  • Provision of a system call application programming interface (API)

• Virtual memory management advantages:

  • Processes are isolated from one another and from the kernel
  • Only part of a process needs to be kept in memory

• Virtual memory split into user space and kernel space which in user mode progams can use just user space but in kernel mode both parts are available

• Certain operations can be performed only while the processor is operating in kernel mode.

• The superuser bypasses all permission checks in the system.

• The term file is commonly used to denote a file of any type, not just a regular file.

• For file names, it is advisable to employ only letters and digits, and the (period), (underscore), and (hyphen) characters which are refered as as portable filename character set.

• A process inherits its current working directory from its parent process.

• A daemon is a special-purpose process which is is long-lived and runs in the background

• IPC mechanisms:

  • signals
  • pipes and FIFOs
  • sockets
  • file locking
  • message queues
  • semaphores
  • shared memory

• Signals are sent to a process by the kernel, by another process (with suitable permissions), or by the process itself.

• Threads are is a set of processes that share the same virtual memory, as well as a range of other attributes except stack which is unique for each of them.

• Threads can communicate with each other via the global variables that they share and IPC mechanisms.