The document provides an overview of the key components of the Linux operating system, including: 1) The Linux kernel, which acts as a resource manager for processes, memory, and hardware devices. 2) Process and memory management systems that control how processes are allocated and memory is allocated and freed. 3) The file system which organizes how files are stored and accessed. 4) Device drivers that allow the operating system to interface with hardware. 5) The network stack which handles network protocols and connections. 6) Architecture-dependent code that provides hardware-specific implementations of core functions.

1. Linux Internal By:- BOSS Team Member CDAC-chennai

3. Kernel

4. Process Management

5. Memory Management

6. File System

7. Device Driver

8. Network Stack

9. Architecture-dependent code

11. Linux is a free operating system based on UNIX standards.

12. LINUX® is a registered trademark of Linus Torvalds.

14. Multi-user

15. Secure

16. Fast

21. Short history of Linux kernel development.

23. Micro kernel (e.g. Windows NT kernel,Mach kernel etc.)‏

26. Preemptive

27. Symmetric multiprocessor (SMP) support.

28. Linux does not differentiate between threads and normal processes.

29. Linux provides an object-oriented device model with device classes,hotpluggable events and user-space device file system(sysfs).

31. The A number denotes the kernel version. It is changed least frequently, and only when major changes in the code and the concept of the kernel occur.

32. The B number denotes the major revision of the kernel. If B is even then kernel is stable else it is unstable.

33. The C number indicates the minor revision of the kernel is only changed when new drivers or features are introduced.

34. minor fixes are handled by the D number.

37. API is a function definition that specifies how to obtain a given service(ex.calloc,malloc ,free etc.), while System call is an explicit request to the kernel made via a software interrupt (ex.brk)‏

38. Invoking a system call by user mode process.

40. Process is represented in OS by Process Control Block.

42. Each element in task list is a process descriptor of the type task_struct .

43. task_struct structure is allocated via slab/slub allocator.

45. Thread is simply a new process that happens to share the same address space as its parent

46. Process creation: fork () creates a child process that is a copy of current process. it differs in PID,PPID. exec() loads new executable in to address space. clone() creates a new process(LWP) with its own identity, but that is allowed to share the data structures of its parent.

47. Process Termination: when process calls system call exit(). Process can also terminate involuntarily by signals or exceptions it can not handle or ignore.

49. The kernel implements a O(1) scheduler algorithm that operates in constant time, regardless of the number of threads vying for the CPU. It supports SMP.

52. Splitting of Memory in a Buddy Heap

54. Whenever two allocated partner regions are both freed up they are combined to form a larger region.

58. mkswap /dev/sdax

59. swapon /dev/sdax

60. swapoff /dev/sdax

62. A file is an ordered string of bytes

63. Files are organized in directory.

64. File information like size,owner,access permission etc. are stored in a separate data structure called inode.

65. Superblock is a data structure containing information about file system

67. ex. copy a file from MS-dos filesystem to Linux

70. Maintaining consistency with fsck , e2fsck

71. lost+found

72. command line utility for Filesystem maintenance

73. tune2fs

74. dump2fs

75. debugfs

77. Linux Device Driver are categorised in three types such as

78. Character Device Driver

79. Block Device Driver

80. Network Device Driver.

82. The sockets layer is the standard API to the networking subsystem and provides a user interface to a variety of networking protocols. From raw frame access to IP protocol data units and up to TCP and the User Datagram Protocol (UDP), the sockets layer provides a standardized way to manage connections and move data between endpoints.

84. Thank You