Operating Systems Exam for Computer Science Degree, Exams of Operating Systems

Download Operating Systems Exam for Computer Science Degree and more Exams Operating Systems in PDF only on Docsity! Cork Institute of Technology Bachelor of Science (Honours) in Software Development – Stage 2 Bachelor of Science (Honours) in Software Development and Computer Networking – Stage 2 (NFQ Level 8) Summer 2006 Operating Systems (Time: 3 Hours) Instructions Answer FIVE questions. All questions carry equal marks. Examiners: Mr. G. Mac Sweeney Dr. M. O’Cinneide Mr. M. Donnelly Dr. J. Buckley Dr. A. Kinsella Q1. Consider the following entry from a typical /etc/passwd file on a Linux system: jane:x:1004:100:Jane:/home/jane:/bin/bash (a) Explain each item in the entry. (7 Marks) (b) Explain how a user is authenticated when he / she logs onto a Linux system. (3 Marks) (c) Explain how Linux maintains the secrecy of users’ passwords. (3 Marks) (d) Explain the purpose of the environmental variable PATH. (2 Marks) (e) In a Linux system, how would you enable one group of users to be able to run a particular program and prevent another group from running it? (2 Marks) (f) State some of the advantages of partitioning a disk. (3 Marks) 2 Q2. (a) What are the main criteria for File Organisation? (5 Marks) (b) Serial (Pile) is a type of file organisation. Name two others. (2 Marks) (c) With reference to Serial (Pile), give an advantage, a disadvantage and an example of where this type of file organisation is appropriate. (3 Marks) (d) In a client-server environment, name three services a server might offer its clients. (3 Marks) (e) In client-server applications, why is host-based processing not regarded as true in a client server relationship? (2 Marks) (f) What is the usual minimum application required for a client in a client-server relationship? (2 Marks) (g) Give three reasons why process migration may be desirable? (3 Marks) Q3. (a) What is deadlock? (3 Marks) (b) What are the three conditions for deadlock? (3 Marks) (c) What is meant by circular wait? (2 Marks) (d) Explain the terms deadlock avoidance and deadlock prevention. (2 Marks) (e) What is a reusable resource? Give an example. (2 Marks) A system with four processes and three resource types is characterised by the Total Resource Vector and Current Resource Allocation as follows: Total Resource Vector R1 R2 R3 7 7 7 Current Resource Allocation R1 R2 R3 P1 2 0 3 P2 1 3 2 P3 2 1 2 P4 1 1 0 (f) Calculate the available resource vector. (2 Marks)