Babu Madhav Institute of Information Technology, UTU

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1 5 Years Integrated M.Sc.(IT) Semester 6 Question Bank UNIX Internals Unit 1: Introduction and Overview of UNIX Answer following in short 1. What is system call? 2. Who are principal designer of UNIX operating system? 3. Write any two points to differentiate between multitasking & multiprogramming. 4. What is kernel in UNIX operating system? 5. List any four features of UNIX system. 6. List the four major system calls used for file system management. 7. Name the data structures used for file system management. 8. Name the data structures used for process management. 9. Write one difference between system call and library function. 10. Write one difference between system call and API. 11. Draw architecture diagram of UNIX operating system. 12. Give any four characteristics of UNIX file system. 13. List any two services of operating system. 14. Draw block diagram of system kernel. 15. What are the responsibilities of file subsystem of UNIX kernel? 16. Justify: "Using large logical blocks increases the effective data transfer rate between disk and memory" 17. State the purpose of boot block. 18. What were the goals of Multics System? 19. List out the levels in which UNIX system architecture is divided. 20. Which system calls are used by the process to interact with file subsystem? 21. What are device drivers? 22. What are Block I/O devices and Raw I/O devices? 23. What is process? 24. What are the responsibilities of process control subsystem of UNIX operating system? 25. List out the system calls used for controlling the processes. 26. What is swapper process? 27. What is the significance of inode? 28. What are file table and user file descriptor table? 29. What is logical device number? 30. List out various structures of file system. 31. What is the importance of Boot block structure of file system? 32. What does the super block describes? 33. What is the use of root inode of file system? 34. What is PID? 35. What is the Process 0? 36. When does Process 0 become swapper process? 37. List out the regions of the process loaded in the memory by the kernel. Also provide their significance. 38. What is u area? 39. What is context of a process? 40. When does a process put itself in sleeping state? 41. When the kernel allows context switching? 42. What is the significance of Kernel Data Structures? Long Questions Page 1 of 28

2 1. Explain features of UNIX system. 2. Operating systems like UNIX provides services both for program and user. Explain. 3. Explain in detail about UNIX system architecture. 4. Describe the block diagram of system kernel. 5. Write a note on UNIX phenomena the file system has "places" and that processes have "life." 6. Why there are two different mechanisms for accessing hardware control and file subsystem? 7. Describe fie system structure in UNIX operating system. Multiple Choice Questions 1. Which of the following is known as the core component of the UNIX operating system? a. System call b. Editor c. Hardware d. Kernel 2. Which of the following system call change the permission of the file? a. Chown b. Chmod c. Stat d. Exec 3. Fork system call is used for a. To divide the process. b. To execute the process c. To create the process. d. To finish execution of process. 4. Which of the following allocates CPU to the process? a. Scheduler module b. Fork system call c. Swapper process d. Exec system call 5. Which of the following can directly interact with the hardware? a. User b. Shell c. kernel d. System call 6. Kernel data structure which is allocated per process is a. Inode table b. File table c. Index node d. User file descriptor table 7. Which block of file system starts at the end of inode list and contains file data and administrative data? a. Data block b. Boot block c. Super block d. Inode list 8. Which of the following process data structure contains a per process region table, whose entries point to entries in a region table? a. User area b. Process table c. Region table d. u area Page 2 of 28

3 9. Which one among the below translate UNIX commands into action? a) Shell b) Kernel c) Command Interpreter d) System call 10. Which one among the below interacts between user and kernel? a) Shell b) Kernel c) Both a) and b) d) System call 11. Which one among below directly interacts with the hardware? a) Shell b) Kernel c) Compiler d) Both b) and c) 12. Which one among below is false with respect to UNIX operating system? a) UNIX considered each and every thing as a file. b) Kernel deals directly with user. c) File and process are two basic entities that support UNIX system. d) Several user can use the system simultaneously. 13. Majority part of UNIX operating system is written using a) Assembly language b) C language c) Java language d) C++ language 14. Who is main contributor for development of Linux? a) Ken Thomson b) Linux Smith c) Linus Torvalds d) Dennis Richi 15. Which among the below given is not the reason for success of the UNIX system? a) System is written in high level language b) It does not use hierarchical file system. c) It has not a complex user interface. d) It is a multiuser, multiprocessing system 16. What among the below can be considered as core of the system? a) Kernel b) Shell c) Operating system d) None of the given 17. Which component among the below translate commands into action in UNIX operating system? a) Shell b) Kernel c) Command Interpreter d) System call 18. Which component interacts between user and kernel? a) Shell b) Kernel c) Command Interpreter d) System call 19. Under what circumstances the kernel provide context switch? a) When a process puts itself to sleep. b) When it exits. c) When it returns from a system call user mode but not a eligible process to run. d) All of the above. 20. Choose the correct one for the statement: All UNIX flavours have one thing in common. a) They uses the same system call b) They share the same kernel c) All UNIX flavour must use same shell d) All system call are based on underlying hardware structure. 21. Where does the system call build up? a) Kernel b) Shell c) Command interpreter d) Application program 22. What are ed and vi? a. Editor b. Kernel c. System Call d. none Fill in the blanks: 1. & have developed UNIX operating system at AT&T Bell laboratory. 2. The set of and the internal algorithms form the body of the kernel. 3. The execution of user process on UNIX systems is divided into and levels. 4. System call is use to change the owner of the file. 5. Raw I/O devices are also called I/O devices. Page 3 of 28

4 6. System call overlay the image of program onto the running process. 7. Internally files are represented with the help of. 8. is the global kernel data structure of file system. 9. The conversion between file system address and disk address is done by. 10. The process that invoked the fork system call is the, and the newly created process is the 11. Process 1 is also known as 12. A special register called indicates the current stack depth. 13. is a directed graph whose nodes represent the states a process can enter and whose edges represent the events that cause a process to move from one state to another. Unit 2: Buffer Cache Answer following in short 1. What do you mean by throughput of the system? 2. What do you mean by block in UNIX operating system? 3. What is the purpose of buffer cache? 4. Which are two parts of buffer? 5. Justify The buffer is the in-memory copy of the disk block. 6. Why a disk block can never map into more than one buffer at a time? 7. How does kernel searches for buffer in the buffer cache? 8. What are the values for the status of buffer? 9. What do you mean by delayed write? 10. What do you mean by buffer status busy? 11. Name the mechanism used for managing free list of buffers. 12. To search effectively, how kernel manages buffers? (which data structure used to manage buffers so that search become effective?) 13. Name algorithm used for buffer allocation. 14. What is the purpose of brelse algorithm? 15. Give one point of difference between bread and breada algorithm. 16. List any two advantages of buffer cache. 17. List any one disadvantages of buffer cache. 18. Why kernel always allocate buffers from the head of the list? 19. What is Buffer? 20. What is Buffer cache? 21. Why does kernel need the buffer cache? 22. What is buffer header contains? 23. When the kernel loses control over a buffer? 24. What is the difference between delayed write and asynchronous write? 25. During which of the asynchronous I/O operations the kernel can invoke block release algorithm from an interrupt handler. Long Questions 1. Explain conditions that describe status of the buffer. 2. Explain the structure of Buffer pool. 3. Describes the scenarios followed by kernel in getblk to allocate a buffer for disk block. 4. Explain getblk algorithm. 5. Explain algorithm for releasing a buffer. 6. Write a note of algorithm for reading from the disk block. Page 4 of 28

5 7. Explain algorithm for writing a disk block. 8. Write a note on pros and cons of buffer cache. 9. Describe the structure of buffer pool. 10. How does free buffers are maintained by kernel in buffer cache? 11. Explain the scenarios of buffer retrieval in case of buffer found on the hash queue. 12. Explain the buffer retrieval scenarios in case of buffer not in hash. 13. Explain race condition in buffer retrieval. 14. Write a note on advantage and disadvantages of buffer cache. 15. Why size of buffer s data area must be at-least as big as size of disk block? 16. What is delayed write? Explain in detail. 17. Explain algorithm to release a buffer. 18. Explain breada algorithm. How it is differs from bread. Multiple Choice Questions 1. Which of the following list of buffers is maintained by the kernel to preserve least recently used order of buffers? a. Busy list b. Locked list c. Free list d. Delay list 2. The free list is maintain as a. Doubly Linked List b. Circular Linked List c. Doubly linked circular list d. Singly linked list 3. During which of the write operation, kernel starts the disk operation immediately but does not wait for its completion. a. Delayed write b. Synchronous write c. Asynchronous write d. None 4. To increase the response time and throughput, the kernel minimizes the frequency of disk access by keeping a pool of internal data buffer called a. Pooling b. Spooling c. Buffer cache d. Swapping 5. Buffer cache helps to a. Store data b. Improved read/write performance c. Allocate memory d. None of the above 6. Which of the following is not the field of buffer header? a. device number b. block number c. status d. size 7. How does free list of buffers are maintained? a. Using link list b. maintaining free list of array Page 5 of 28

6 c. doubly link list d. doubly link list with least recently used mechanism 8. Which of the following is used to search buffer of disk block in buffer pool? a. device number and inode number b. block number and inode number c. device number and status d. device number and block number 9. When kernel retrieves block, its buffer is found in hash queue and is free, which of the following sequence occurs (multiple choice) a. the buffer removed from hash queue b. the buffer marked as busy c. the buffer removed from the free list d. the buffer added into hash queue 10. When kernel retrieves block, its buffer is not available in hash queue, which of the following sequence occurred a. Process waits for buffer is available in hash queue b. A free block is allocated from the head of free list c. A free block is allocated from the tail of free list d. None of above Fill in the Blanks 1. A buffer consists of and. 2. The kernel must write the buffer contents to disk before reassigning the buffer; this condition is known as. 3. System call allocates the buffer until the umount system call is called. 4. When doing write, the kernel starts the disk operation immediately but does not wait for its completion. 5. Function is used by the kernel at the time of search block in the queue. Unit 3: File Systems Short Questions 1. Which information is obtained by using inbuilt macros S_ISREG of stat data structure? 2. Which kernel data structure stores the information about permissions to access a file? 3. Define inode. 4. List the data structures and their relationship when a regular file is opened. 5. What is remember inode? Where does it located? 6. List the fields of super block. 7. How current byte offset is maintained by the file table? 8. What is the purpose of lseek() system call? 9. What is the return value of lseek() system call 10. How a user can move from beginning to end or in the middle of the file? 11. What is file descriptor? 12. What is the difference between user file descriptor table and file table? 13. Does each entry in the user file descriptor table have a separate file table associated with it? 14. List the information stored in inode block. 15. Why ialloc algorithm is required while creating a new file? 16. Which algorithm is used to free the inode used by the file? Page 6 of 28

7 17. Which fields are additional in in-core inode than (disk) inode? 18. Why does inode number start from 1 not from 0? 19. What is the purpose of link system call? Give syntax with parameter description. 20. What does directory entry consists of? 21. How kernel searches for free inodes? 22. Give any one situation for buffer status contains invalid data. 23. What do you mean by delay-write status of buffer? 24. Give one difference and one similarity between algorithm bread and breada. 25. What happens when inode is released and free list of inode in super block is full? 26. What do you mean by system call? How it is differs from C library function? 27. What is the return value and type of creat() system call? 28. Where does file name stored? 29. List out various Buffer allocation algorithms. 30. Which algorithm converts a user-level path name to an inode? 31. List out various lower level file system algorithms. 32. What is inodes? 33. List out fields of disk inodes. 34. What is the significance of Number of link field of disk inode? 35. List out various file types supported by the UNIX file system. 36. When the contents of an inode changes? 37. What is the difference between in-core inode and buffer header? 38. Give the formula to compute the byte offset of the inode in the block. 39. Why the process that goes to sleep waiting for a free inode never wake up? 40. Which are the two extensions to the classic inode structure? 41. What are directories in UNIX operating system? 42. What is the significance of. (dot) and.. (dot dot) file names in the directory? 43. What mkfs program does? 44. What is the meaning of read permission on directory? 45. What do write permission on directory signify? 46. Which permission the user must have to search the directory? 47. List out the fields of super block. 48. Give the syntax for open system call. 49. Which are the first three user file descriptors? 50. What is the significance of count parameter in read system call? 51. What is the use of lseek system call? 52. What is the significance of modes parameter of Creat system call? 53. What is the difference between chdir and chroot? 54. What is the significance of stat and fstat system call? 55. Which information is returned by stat system call? 56. What is the use of dup system call? 57. What is the importance of options parameter in mount system call? 58. Which system call removes a directory entry for a file? Long Questions 1. Explain various fields of disk inodes. 2. Write a note on fields of in-core copy of an inode. 3. Explain an algorithm for allocation of In-core inodes. 4. Explain an algorithm for releasing an inode. 5. Write an algorithm to convert Byte Offset to Block Number in File System. 6. Explain in detail structure of regular file. Page 7 of 28

8 7. Explain an algorithm to Conversion of a Path Name to an inode. 8. Write a note on super block. 9. Explain ialloc algorithm to assign new inodes. 10. Explain algorithm to free an inode. 11. Explain Race Condition in Assigning inodes. 12. Write a note on algorithm for allocating disk block. 13. Explain open and close system call in detail. 14. Explain read and write system call. 15. Write a program for reader and a writer process. 16. Explain system call used for adjusting the position of file I/O. 17. Explain the system call used for creating a file. 18. Write a note on the system call that is used to create special file. 19. Write a note on pipes. 20. Write a note on mounting and unmounting file systems. 21. Explain in detail the field in entry of the mount table. 22. Explain link and unlink system call. 23. Explain file system consistency and race conditions during the use of unlink system call. 24. Write a note on file system abstraction and file maintenance. 25. Explain in detail about the structure of regular file. 26. State the importance of file table in UNIX system. What information is stored in it? 27. Explain the system call used for creating the special files. 28. Draw a diagram representing kernel data structures after executing open(). 29. Write an algorithm for demonstration lseek(). 30. Differentiate between open() and creat() system call with example. 31. Demonstrate usage of read () & write() system call for copying content of file1 to file Briefly explain file creation concept. 33. State the purpose of in-core inode entries in detail which are not available in (disk) inode. 34. Which system call is used to read inode entries? Explain in detail with example. 35. Explain algorithm for converting the path name to inode. 36. Specify how the open () system call is used to emulate the function performed by the shell s (i)> (ii)>> symbols? 37. Describe any one algorithm from following in detail. ialloc, iput, bmap, ifree, alloc, iget Multiple Choice Questions 1. What system call read a byte at a time from the standard input? a. read(0,buff,0); b. read(1,buff,1); c. read(2,buff,1); d. read(0,buff,1); 2. Which of the following information does not stored in inode? a. File size b. File name c. File owner d. File group 3. Directory entry consist of. a. File type, file name and file size b. File type, file name and i-node c. File type and i-node d. File name and i-node 4. Which of the following file descriptor represent standard output? Page 8 of 28

9 a. 0 b. 1 c. 2 d. None of above 5. Which system call is used to read content of the file? a. get b. fread c. getch() d. read() 6. When kernel retrieves block, its buffer is found in hash queue and is free, which of the following sequence occurs? (multiple choice) a. the buffer removed from hash queue b. the buffer marked as busy c. the buffer removed from the free list d. the buffer added into hash queue 7. When kernel retrieves block, its buffer is not available in hash queue, which of the following sequence occurred? a. Process waits for buffer is available in hash queue b. A free block is allocated from the head of free list c. A free block is allocated from the tail of free list d. None of above 8. UNIX stores list of free blocks in. a. I-node block b. Super block c. Data block d. Both b and c List of free inodes are maintained in. a. Boot block b. Super block c. I-node block d. Data block 10. Type field of i-node stored zero means. a. i-node is allocated b. i-node is free c. i-node is locked d. i-node is corrupted 11. Which of the following information is not stored in superblock? a. Size of filesystem b. Size of i-node table c. List of free blocks d. List of allocated i-nodes 12. Which of the following is stored in in-core inode but not in disk i-node? a. File size b. File permission and type c. Link cout d. Reference count 13. Which of the following is maintained by file table? a. a pointer to in-core inode table b. the offset of next read or write in the file c. access rights (r/w) allowed to the opening process. d. reference count e. all of above 14. Use of dup(intfd) system call is. a. Create duplicate file b. Copy a file descriptor into the first free slot of the user file descriptor table c. Copy a file content d. Copy a file table entry in file table maintained by kernel 15. Which of the following system call is used to creat a new file? a. open() Page 9 of 28

10 b. creat() c. both open() and creat() can be used d. none of above 16. Which of the following system call is used to delete a file? a. delete() b. close() c. unlink() d. link() 17. A process may query status of a file by using system call. a. open() b. read() c. status() d. stat()/fstat() 18.Which of the following is not buffer allocation algorithm? a. Alloc b. Brelse c. Getblk d. Breada 19. Which of the following is buffer allocation algorithm? a. Alloc b. Free c. Ialloc d. Breada 20. Which of the following is lower level file system algorithm? a. Bread b. Bwrite c. Breada d. Free 21. An inode is on the free list only if its reference count is a. -1 b. 0 c. 1 d Except which of the following system call, an inode is allocated and released. a. Open b. Close c. Alloc d. Free 23. The file name. (dot) in the directory gives the inode for a. Current directory b. Parent directory c. Root directory d. Child directory 24. Write permission allows a process to create new directory entries or remove old ones with the help of system call except which of the following. a. Creat b. Mknod c. Link d. Open 25. Which of the following algorithm parses the path name one component at a time, converting each component into an inode? a. Bmap Page 10 of 28

11 b. Namei c. Iget d. iput 26. To change the directory which of the following system call is used? a. Chgdir b. Chdir c. Cd d. cddir 27. Which of the following utility program organizes the data blocks of a file system in linked list? a. Md b. Mkdir c. Mkfs d. mdfs 28. Which of the following system call manipulate an inode? a. Open b. Close c. Write d. stat 29. Which of the following system call does not manipulate an inode? a. Chdir b. Chroot c. write d. chown, 30. Which of the following file operation does not use the file descriptor returned by open system call? a. Reading b. Writing c. Creating d. seeking 31. The user file descriptor standard error is indicated by a. -1 b. 0 c. 1 d The reference parameter value 2 of lseek system call indicates a. Beginning of file b. End of file c. Beyond the end of file d. At current position 33. Which of the following system call creates special files? a. Mknod b. Creat c. Open d. mkdir 34. Which of the following system call is used to change the owner of the file? a. Chmod b. Chroot c. Chown d. chgrp 35. Which of the following system call copies the file descriptor into the first free slot of the user file descriptor table? a. Copy Page 11 of 28

12 b. Fcopy c. Fdup d. dup 36. Which of the following system call removes the directory entry of the file? a. Rm b. Rmdir c. Unlink d. unlnk Fill in the blanks 1. & algorithm assign and free inodes for the files respectively. 2. & algorithm allocate and free disk blocks for files respectively. 3. defines the set of users who have access rights to a file. 4. A field of in-core copy of an inode, indicating the number of instances of the file that are active. 5. An inode is active when a process allocates it, such as when a file. 6. The is set during execution of a system call to prevent other processes from accessing the mode while it is in use. 7. In algorithm is the kernel attempts to take an inode from the free list but finds the free list empty, it reports an error. 8. When the kernel releases an inode, it its in-core reference count. 9. Algorithm converts a file byte offset into physical disk block. 10. is a file whose data is a sequence of entries, each consisting of an inode number and the name of a file contained in the directory. 11. is a null terminated character string divided into separate components by the slash ("/") character. 12. The file name.. (dot dot) in the directory gives the inode for. 13. The algorithm parses the path name one component at a time, converting each component into an inode based on its name and the directory being searched, and eventually returns the mode of the input path name. 14. The current directory of the first process in the system, process 0, is the directory. 15. The current directory is stored in the process, and the system root mode is stored in a. 16. A process can execute the system call to change its notion of the file system root. 17. An inode is free if its type field is. 18. A file type field indicates that the disk mode is assigned. 19. The file system contains an array that is used to cache the numbers of free disk blocks in the file system. 20. The utility program organizes the data blocks of a file system in a linked list, such that each link of the list is a disk block that contains an array of free disk block numbers, and one array entry is the number of the next block of the linked list. 21. The open system call returns an integer' called the. 22. System call is used to change the directory. 23. System call is used to change the access permission of the file. 24. The system call connects the file system in a specified section of a disk to the existing file system hierarchy. 25. The system call disconnects a file system from the hierarchy. 26. The system call that links a file to a new name in the file system directory structure, creating a new directory entry for an existing inode is. Page 12 of 28

13 Unit 4: Process Management Short Questions 1. Give significance of PID & PPID. 2. Mention the use of the fork(). 3. How do you display all processes running on your system? 4. Name five important process attributes that are inherited by the child from its parent. 5. Kernel said to be non-preemptive. Note your comments on previous statement. 6. Define swapping & paging. 7. List any two advantages and disadvantages of kernel data structure. 8. Define pathname component. 9. Differentiate between user mode & kernel mode. 10. What are the 3 levels of UNIX operating system? 11. Define system call interface. 12. How will you kill the last background job without knowing its PID? 13. Define zombie state of process transition. 14. In which situation mode is used in open()? 15. Define signal. 16. What is context of process? 17. How you can avoid creating a process for command execution when it is to be executed from shell prompt? 18. Which programs are executed by spawning a shell? What does the second shell do? 19. Mention the use of lseeksystem call. 20. Write the I/O parameters saved in the U area. 21. Define init process. 22. What is the life time of the process? 23. What is Zombie state? 24. List out various states of the process. 25. What is user mode and kernel mode? 26. Which are the kernel data structures that describe process states? 27. What is the significance of UID field in process table data structure of kernel? 28. What is the use of PID field of process table? 29. What is the importance of Limit Field of u area data structure? 30. What is shared memory? 31. What is virtual address space? 32. What is region? 33. What is pregion for process? 34. Which is the value that permission field of pregion contains? 35. What are pages? 36. What is the significance of page table? 37. What does context of the process contains? 38. What is the importance of system-level context of the process? 39. What is the use of PS register in register context of the process? 40. What is program counter? 41. What does stack pointer contains? 42. What is the use of general-purpose register? 43. What is the significance of kernel stack of system-level context of process? 44. List out various system calls used to manage process. 45. What is the significance of exit system call? Page 13 of 28

14 46. What does kernel do for creating user-level context for child process? 47. What is the significance of exec system call? 48. What does magic number contains? 49. What is sticky bit? 50. What is shell? 51. Which operation is performed by shell for executing any command? 52. What is bootstrap? 53. What is init process? 54. What is the PID of init process? 55. What is the significance of daemons process? Long Questions 1. Explain various process states with diagram. 2. Write a note on Process states and transitions. 3. Write a note on State transition model of the process. 4. Explain various fields that are present in process table data structure of kernel. 5. Explain in details fields of u area data structure of kernel. 6. Write a note on Processes and regions. 7. Explain Mapping of Logical to Physical Page Numbers. 8. Write a note on layout of the kernel. 9. Write a note on u area. 10. Explain the components contained by register context of process. 11. Write a note on components of system-level context of process. 12. Write a note on Components of the Context of a Process. 13. Write a note on process creation. 14. Explain the sequence of operations performed by kernel for the fork system call. 15. Explain fork algorithm. 16. Explain algorithm for exit system call. 17. Explain the system call used to invoke other programs in UNIX. 18. Explain the logical format of executable file generated by assembler or loader. 19. Explain the cases when kernel removes the entries for sticky bit text regions. 20. Write a note on shell. 21. What operations does shell perform to execute ls 1 I wc. 22. Write a note on bootstrap sequence. 23. Explain an algorithm for booting the system. 24. Explain an algorithm for init. 25. Describe the state transition that a process undergoes during its lifetime. 26. Which memory structures are responsible for storing the data related to process which are only accessible to the running process itself? Give your explanation by making use of diagram. 27. Why kernel does not prempt process running in kernel mode in UNIX system? 28. List internal steps after execution of fork(). 29. Discuss what happens to open files on creation of child process. Illustrate using program and by drawing. 30. State the purpose of using Wait(). Explain wait() with different example of getting status of child. 31. List steps performed after executing exit(). 32. Which steps are performed in UNIX operating system after occurrence of interrupt while executing a process in kernel mode? 33. In user mode, a process can directly access hardware? If not, why? If yes, how? 34. Discuss booting sequence. 35. Differentiate between exceptions & interrupts. 36. Explain usage of exec() in detail. Page 14 of 28

15 37. What are signals? Name a way of generating a signal from the keyboard. Why should we use kill with signal names rather than their numbers? 38. Is there any process in the system whose PID is 0 (i.e. Zero)? Give significance of it. 39. Explain in detail about context of the process in UNIX system. Multiple Choice Questions 1. What is a context switch? a. Kernel switches from executing one process to another. b. Process switches from kernel mode to user mode. c. Process switches from user mode to kernel mode. d. None of the above 2. Pid of init process is. a. 0 b. 1 c d. None of the above. 3. What is the default maximum number of processes that can exist in Linux? a b c d. Unlimited 4. How do you get parent process identification number? a. Waitpid b. getpid() c. getppid() d. parentid() 5. The process which terminates before the parent process exits becomes.. a. Zombie b. Orphan c. Child d. None of the above 6. If fork() system call returns -1, then it means. a. No new child process is created b. The child process is an orphan c. The child process is in Zombie d. None of the above. 7. Fork returns to parent process on success. a. 0 b. child process id c. parent process id d. none 8. How many times printf() will be executed in the below mentioned program? main() { int i; for (i = 0; i < 4; i++) fork(); printf( my pid = %d\n, getpid()); } a. 4 b. 8 c. 16 d What is the output of the below code? void exit_handler1(); void exit_handler2(); int main() { intpid; Page 15 of 28

16 atexit(exit_handler1); atexit(exit_handler2); pid = fork(); if(pid == 0) { _exit(0); } else { sleep(2); exit(0); } return 0; } a. Only child executes the exit_handler 1 and 2. b. Only parent executes the exit_handler 1 and 2. c. Both parent and child executes the exit_handler 1 and 2. d. Neither parent nor child executes the exit_handler 1 and What is output of the following program? int main() { fork(); fork(); fork(); if (wait(0) == -1) printf( leaf child\n ); } a. leaf child will be printed 1 times b. leaf child will be printed 3 times c. leaf child will be printed 4 times d. leaf child will be printed 8 times 11. Which niceness value among the following indicates most favourable scheduling? a. 0 b. 20 c. 5 d Nice can be used by an ordinary process to. a. increase the priority of a process b. decrease the priority of a process c. increase or decrease the priority of a process d. None of the above. 13. State of a process changes from run to blocked/wait when.: a. Waiting for disk read occurs b. Time slice expires c. Waiting for CPU occurs d. All of the above 14. Which statements concerning process IDs are valid? a. Process IDs are stored in the respective i-nodes. b. It is assured that no two concurrently running processes have the same process ID. c. The process IDs are only unique with respect to each user. d. The process ID of the interactive shell may be returned with the command echo $? 15. Which statements concerning process IDs are valid? a. Shell and Subshell have the same process ID. b. The init process is always assigned process ID 1. c. Following a fork system call, father and son have the same process ID. d. None of above is true 16. init run-level for system shutdown is. a. 3 b. 2 c. 1 d When process executed exit system call then it comes to a. Zombie state Page 16 of 28

17 b. Ready state c. Sleeping state d. Wakeup state 14. When parent process execute the fork system call, the process comes to a. Ready state b. Zombie state c. Created state d. Running state 15. When the system clock interrupts the process, it comes to a. User running state b. Kernel running state c. Ready state d. Running state 16. Which of the following u area field record the time the process (and its descendants) spent executing in user mode and in kernel mode? a. Pointer b. Terminal c. Error d. Timer 17. Data address is used for access to a. Global data variable b. instructions or subroutine calls c. data structures local to a subroutine d. Virtual address 18. Which of the following kernel data structure contains information about the regions allocated to the process? a. Process table b. U area c. User descriptor table d. Region table 19. Which of the following is not the value of permission field of pregion? a. Read-only b. Read-write c. Read-execute d. Write-only 20. Which of the following is not present in user-level context of process? a. Process text b. Process data c. User stack d. permission 21. Which of the following system call allows a process to allocate more memory dynamically? a. Creat b. Brk c. New d. fork 22. Which of the following system call is used to invoke other programs? a. Exec b. Creat c. Fork d. new 23. Which of the following is not the system call to manage the process? Page 17 of 28

18 a. Fork b. Exec c. Creat d. open 24. Which of the following are the tasks that are performed by daemon process? a. administration and control of networks b. Execution of time-dependent activities c. line printer spooling d. All of the above. Fill in the blanks 1. The process executed the exit system call and is in the state. 2. The process enters the state model in the state when the parent process executes the fork system call and eventually moves into a state where it is ready to run. 3. When the process scheduler picks the process to execute, then the process enters the state, where it executes fork system call. When the process completes the system call, it may move to state, where it executes in user mode. 4. The field of process table data structure of kernel identifies the process state. 5. The process table contains fields that must always be accessible to the, but the u area contains fields that need to be accessible only to the process. 6. The table records the files the process has open. 7. A field of u area data structure masks mode settings on files the process creats. 8. A field of u area restricts the size of a process and the size of a file it can write. 9. A is a contiguous area of the virtual address space of a process that can be treated as a distinct object to be shared or protected. 10. The System V kernel divides the virtual address space of a process into logical. 11. Entries may exist in the process table, the u area, or in a separately allocated area of memory, dependent on the implementation. 12. The memory management hardware divides physical memory into a set of equal-sized blocks called. 13. The region table entry contains a pointer to a table of physical page numbers called a. 14. The system allows address references via the kernel register triples only when in mode. 15. A process can access its u area when it executes in mode but not when it executes in mode. 16. The only way for a user to create a new process in the UNIX operating system is to invoke the system call. 17. After the fork system call is executed, the two processes have identical copies of their user-level context except for the return value. 18. Processes on a UNIX system terminate by executing the system call. 19. Processes and exist throughout the lifetime of a system. 20. The process is a process dispatcher, spawning processes that allow users to log in to the system, among others. 21. The init process spawns processes to monitor the terminal lines configured on a system. Unit 5: Inter-process Communication Short Questions 1. What is signal? How it can be sent to other process? Page 18 of 28

19 2. What happens to process on the receipt of the signal? 3. What do you mean by anonymous pipe? 4. Why pipe used only for half duplex communication? 5. What is return value of pipe() system call on success? 6. Why does pipe is available to use in related process? 7. Give name of any two signal which cannot be ignored or catch by a process. 8. What do you mean by installing signal handler? 9. What do you mean by re-installing signal handler? 10. When does process checks for arrival of signal? 11. What do you mean by transient pipe? 12. What is named pipe? 13. List System V IPC mechanism? 14. Which command is used to query status of System V IPC? 15. Which system call is used to remove message queue? 16. Which system call is used to access semaphore? 17. What will be return value of getshm() system call? 18. What is the significant of ftalk() call? 19. What if reader process closes the (all)read end of the pipe? 20. What is the drawback on pipe? 21. List out various types of pipes? 22. What is the use of pipe? 23. What is signal? 24. List out cases for handles the signals. 25. What is the significance of function parameter in signal system call? 26. What is the use of setpgrp system call? 27. What is the purpose of kill system call? 28. Give the formula to find index into the table of data structures from the descriptor for IPC mechanism. 29. List out the system calls that are used for messages. 30. What is the purpose of msgsnd system call? 31. What is the significance of msgget system call? 32. List out system call used to manage shared memory. 33. What is semaphore? 34. Which are the elements that a semaphore consists of in UNIX System V? 35. Which system call of semaphore is used to create and gain access to a set of semaphores? 36. What is the purpose of IPC_NOWAIT flag in semop system call? 37. What is the significance of SEM_UNDO flag in semop system call? 38. What is socket? 39. List out the parts of kernel structure. 40. What is the importance of protocol layer of kernel structure? 41. What is device layer of kernel structure? 42. What is the use of socket system call? 43. What is the purpose of connect and listen system call? 44. What is shutdown system call? 45. What is return by getsockname system call? Long Questions 1. Write a note of signals in System V UNIX. 2. Explain an algorithm for recognizing signals. 3. Explain Signal system call. Page 19 of 28

20 4. Write a note on anomaly with signals. 5. Write a note on common properties of System V IPC mechanism. 6. Explain message queue in detail. 7. Explain message system call used to send and receive messages. 8. Write a note on msgget and msgctl system calls. 9. Explain an algorithm for msgsnd. 10. Explain an algorithm for receiving a message. 11. Write a note on shared memory. 12. Explain the system calls used to attach and detach the region to the virtual address space. 13. Explain algorithm for attaching shared memory. 14. Explain semaphore in detail. 15. Explain various system calls of semaphore. 16. Explain an algorithm for semaphore operations. 17. Explain Socket model. 18. Explain Socket and Bind system call. 19. Which system call is used to send a signal? Give its syntax and parameter description. What if signal not sent? 20. What happens to process on the receipt of the signal? Explain. 21. Why does process will not react to signal on receipt of signal in case when it occurs more than one time? Discuss its solution. 22. How signal mechanism is used as communication mechanism between processes? Explain. 23. Which signal is sent to the parent process on child termination? Illustrate by giving example. 24. What do you mean by anonymous pipe? Why it called anonymous? 25. Why unnamed pipe used only in related processes? 26. Why pipe is used in half duplex communication? Explain by giving example. 27. What is FIFO? How it is differs from pipe (unnamed pipe)? How it can be created and accessed? 28. Write programs to demonstrate communication between two arbitrary process using FIFO. 29. Explain different scenario in case of inter processes communication done using FIFO. 30. How a parent process can wait for termination of its child process? Explain with an example. 31. How a child process can pass exit status to its parent process? Illustrate using program. 32. Explain system call wait(), waitpid(). 33. Explain internal working of exit() system call. 34. Explain block and non block operation in msgrcv() and msgsnd() system call. 35. Describe the common characteristics of System V IPC mechanism. 36. How process can obtain shared memory region for communication? Also explain reading and writing into shared memory with example. 37. What operation can be performed on semaphore? Explain each with example. 38. How semaphore can be used to solve critical section problem? Multiple Choice Questions 1. Which of the following system call is used to create named pipe? a. pipe b. open c. mknod d. fifo 2. Which system call is used by the process to send a signal to other process(es). a. signal b. msgsnd c. kill d. sndsignal Page 20 of 28

21 3. The kernel handles a signal only when process is in: a. User mode b. Kernel mode c. Both d. Sleeping mode 4. Process can ignore signal using: a. signal system call b. kill system call c. trap system call d. handle system call 5. Which is true regarding pipes? a. half duplex b. full duplex c. message boundaries are preserved d. Unordered data 6. On receipt of signal process can do which of the following action. (Tick all answer) a. Exits b. Ignore c. Executes function d. Sends signal 7. Which system call is used to get process id of last process which sends last message on message queue? a. msgsnd b. msgrcv c. msgget d. msgctl 8. Which system call is used to remove message queue structure from the kernel? a. msgsnd b. msgrcv c. msgget d. msgctl 9. Which system call is used to read data from the shared memory? a. read b. shmat c. shmdt d. None of these 10. What information is stored in semaphore structure for each semaphore? a. The PID of process that performed last operation b. The current value of semaphore c. Number of process waiting for resource to become available d. All of above 11. Which of the following is not an element of sembuf structure? a. The number of the semaphore you wish to deal with b. Process Id of current process c. The operation to perform (positive, negative, or zero) d. Operational flags 12. The system call semctl() can be used to do following a. To retrieve shared memory structure b. To perform various command on shared memory c. To create semaphore d. To remove semaphore set from the system 13. The persistency of a FIFO is Page 21 of 28

22 a. process b. kernel c. file system d. none 14. Advantage of FIFO over pipe is a. related processes can communicate b. unrelated processes can communicate c. none 15. What mkfifo() creats? a. pipe b. unnamed pipe c. named pipe d. msg queue 16. System V IPC common attributes are a. key b. id c. owner d. all the above 17. Which one of the following is not system V IPC? a. Shared Memory b. Semaphores c. FIFO d. Message Queues 18. Which system call is used to create Sys V message Queue. a. msgget b. shemget c. semget d. msgctl 19. Which is not the correct option for removing a message queue a. ipcrm -Q b. ipcrm -q c. ipcrm -m d. None 20. Message queues are created in a. userspace b. kernelspace c. both d. none 21. Command used to check shared memory is a. ipcs b. ipcs -m c. ipcs -s d. ipcs -q 22. Which is Fastest IPC? a. Message Queue b. shared memory c. Socket d. all 23. What is the persistancy level of Shared memory segments? a. signal b. process Page 22 of 28

23 c. file system d. kernel 24. The structure which keeps the information about shared memory in the kernel is a. struct ipc_perm b. struct semid_ds c. struct shmid_ds d. struct msgid_ds 25. One process requires M resource to complete a job. What should be the minimum number of resources available for N processes so that at least one process can continue to execute without blocking/waiting? a. M * N b. M * N 1 c. M * N + 1 d. M 26. Semaphore P( ) operation usually does the following: a. descrements the semaphore count and the process sleeps if needed b. increments the semaphore count c. wakes up a sleeping process 27. Which call to use to set the resource count of semaphore? a. semget( ) b. semctl( ) c. sem_setcount( ) d. sem_set_count( ) 28. Which of the following IPC is fastest amongst all? a. Message queue b. Semaphore c. Shared memory d. All are equal 29. Which of the following inform processes of the occurrence of asynchronous events? a. Signals b. Pipe c. Semaphore d. message 30. Which of the following system call is used to initializes process group number? a. Setgroup b. Setpgrp c. setprocgrp d. Setpgrp 31. Which of the following system call is used to send signal to the process? a. Send b. SendSignal c. Kill d. KillSignal 32. Which of the following value of pid signify that the kernel has send the signal to all the processes with process ID pid? a. Negative b. Zero c. Positive d. Non-zero 33. Which of the following value of pid signify that the kernel has send the signal to all the processes whose real user ID equals the effective user ID of the sender? Page 23 of 28

24 e. -ve f. 0 g. +ve a Which of the following system call is used to receive the message? a. Msgget b. Msgctl c. Msgsnd d. msgrcv 35. Which of the following parameter of msgsnd system call specifies the action the kernel should take if it runs out of internal buffer space? a. Msgqid b. Msg c. Count d. flag 36. Which of the following parameter of msgrcv system call specifies the size of the data array in msg? a. Msg b. Maxcount c. Type d. flag 37. Which of the following system call of shared memory, create a new region of shared memory? a. Shmget b. Shmcreat c. Shmat d. shmdt 38. Which if the following parameter of shmctl system call is the address of a user-level data structure that contains the status information of the shared memory table entry when querying or setting its status? a. Id b. Cmd c. Shmstatbuf d. statbuf 39. Which of the following system call allow processes to synchronize execution by doing a set of operations atomically on a set of semaphores? a. Creat b. Semaphore c. Message d. shmat 40. Which of the following system calls is used to manipulate the values of semaphore? a. Semget b. Semctl c. Semop d. semval 41. Which of the following is not the layer of kernel structure? a. Socket b. Protocol c. Device d. hardware 42. Which of the following system call is used to requests that the kernel make a connection to an existing socket? a. Listen b. Socket Page 24 of 28

25 c. Bind d. connect 43. Which of the following system call return the name of the socket? a. Getsockname b. Getsckname c. RetSckName d. None Fill in the blanks 1. Mechanisms allow arbitrary processes to exchange data and synchronize execution. 2. Signals inform processes of the occurrence of asynchronous events. 3. The kernel uses the process to identify groups of related processes that should receive a common signal for certain events. 4. The system call initializes the process group number of a process and sets it equal to the value of its process ID. 5. The system call is use to send signals to the process. 6. If pid is a integer, the kernel sends the signal to the process with process ID pid. 7. If pid is, the kernel sends the signal to all processes in the sender's process group. 8. If pid is, the kernel sends the signal to all processes whose real user ID equals the effective user ID of the sender. 9. If pid is a integer but not 1, the kernel sends the signal to all processes in the process group equal to the absolute value of pid. 10. System call returns a message descriptor that designates a message queue for use in other system calls. 11. System call has options to set and return parameters associated with a message. 12. System call sends the message. 13. System call is used to receive the message. 14. In msgsnd system call, is the descriptor of a message queue typically returned by a msgget call. 15. Processes can communicate directly with each other by sharing parts of their virtual address space and then reading and writing the data stored in the. 16. The system call creates a new region of shared memory or returns an existing one. 17. The system call logically attaches a region to the virtual address space of a process. 18. The system call detaches a region from the virtual address space of a process. 19. The system call manipulates various parameters associated with shared memory. 20. The parameter of shmctl system call is the address of a user-level data structure that contains the status information of the shared memory table entry when querying or setting its status. 21. The system calls allow processes to synchronize execution by doing a set of operations atomically on a set of semaphores. 22. The system call of semaphore is used to create and gain access to a set of semaphores. 23. The layer of kernel structure provides the interface between the system calls and the lower layers. 24. The system call receives incoming requests for a connection to a server process. 25. & system calls transmit data over a connected socket. Unit 6: Input /Output Management Short Questions Page 25 of 28