2.

1 Different services of Operating

Unit-II System
Services and 2.2 System calls :Concept , Types of
System Calls
Components of 2.3 OS Components: Process
Operating System Management, File Management, I/O
Management, Main Memory

(10 Marks) System Management, Secondary

Management. ,Networking Management
2.4 Use of Operating System tools:
User Management,
Security Policy, Device Management,
Performance Monitor & Task Scheduler

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Services of Operating System
1. User Interface
2. Program Execution
3. I/O operation
4. File Manipulation
5. Error detection
6. Communication
7. Protection/ Security
8. Resource allocation
9. Accounting

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 Services of Operating System

1. User Interface
Command Line Interface (CLI)

Command Prompt Terminal (Ubuntu)

(Windows)
 Services of Operating System
1. User Interface
Graphical User Interface(GUI)

Windows Ubuntu
 Services of Operating System

2. Program Execution
 Operating System provide facility to user to create
program then it loads in memory and finally get
executed.
 After successful execution, program get terminated
successfully
 After unsuccessful execution , program terminated
abnormally by indicating errors

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 Services of Operating System
3. I/O operation
 It provide facility to perform input/output operation with hardware
or different process.
 e.g Read or Write data on I/O device.

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 Services of Operating System
4. File Manipulation
Program needs to read a file or write a file.
The operating system gives the permission to
the program for operation on file.
Permission varies from read-only, read-write,
denied and so on.
Operating System provides an interface to
the user to create/delete files/directories.
Operating System provides an interface to
create the backup of file system.

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 Services of Operating System
5. Error Detection
An error is one part of the system
may cause malfunctioning of the
complete system. To avoid such a
situation the operating system
constantly monitors the system for
detecting the errors.
Errors may occur in CPU, Memory,
I/O devices or programs
For each type of error, Operating
System must take corrective step to
recover from that.

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 Services of Operating System

6. Communication
 Exchange of information between
processes executing either on the same
computer or on different systems tied
together by a network.
 Implemented via shared memory or
message passing.
 Specific hardware or user program
used for this.

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 Services of Operating System

7. Protection
 Protection refers to mechanism or a
way to control the access of programs,
processes, or users to the resources
defined by a computer systems.
 Operating System ensures that
external I/O devices are protected from
invalid access attempts.
Operating System provides
authentication feature for each user by
means of a password.

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 Services of Operating System

8. Resource Allocation
 Allocating resources to multiple users or
multiple jobs running at the same time.
Resource may be hardware – CPU, Memory,
I/O Device or software- Programs
 It must handle situation in such manner
that all user or jobs get resources whenever
they demand

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 Services of Operating System

9. Accounting
 Keep track of and record which users use how much
and what kinds of compute resources for account
billing.
 It can be use to detect error/bug or to add some
resources or for protection of Operating System.
It is also used to debug/modify/upgrade the system

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 System call
 System Calls: System calls provide an interface
between the process and the Operating System.

Safe Mode
There are two modes of
Privileged Mode operation in the operating
system to make sure it
works correctly.

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System call

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System call Implementation:

Eg of System
calls:

1. open()
2. close()
3. read()
4. write()

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 Types of System call

1. Process Control system calls

2. File Manipulation system calls

3. Device management system calls

4. Information management system calls

5. Communication system calls

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 Types of System call
 Process Control
 End
 Abort
 Load
 Execute
 Create
 Terminate
 Suspend
 Resume
 Get and Set process attributes: id,
state, priority
 Wait for time, Event
 Change the priority of process 17
 Types of System call

 File manipulation
Create File
 Delete File
 Open File
 Close
 Read
 Write
 Reposition
 Get File Attributes
 Set File Attributes
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 Types of System call

 Device Management

 Request device
 Release device
 Read
 Write
 Reposition
 Get and Set device attributes:
id, name, type, speed

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 Types of System call

 Information Management

 Get Time
 Set Time
 Get system data
 Set system data
 Get and Set Process, File or Device
attributes

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 Types of System call

 Communication

 Create connection
 Delete connection
 Send message
 Receive message
 Transfer status information
 Logically attach and detach remote
device

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 Operating System Components
Operating System breaks into modules or parts
which perform specific task

1. Process Management
2. Memory Management
3. File Management
4. I/O System Management
5. Networking Management
6. Secondary Storage Management

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 Operating System Components
1. Process Management
Process: Program in Execution state
Activities involve in handling process called process
management
Process is active entity which require resources for
execution
Activities:
 Creation of user and system process
Suspending and resuming process
Mechanism for process communication,
Synchronization, deadlock handling
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 Operating System Components

2. Main Memory Management

 RAM is main memory present in system.
 Activities involve in handling memory called memory
management
 Memory management require for smooth functioning of System

 Activities:
 Tracking of memory
 Deciding priority to allocate memory
 Allocation and Deallocation of memory

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 Operating System Components
3. File Management
 File: Collection of programs and data
 Directory: Collection of Files
 Activities involve in handling Files called File management

 Activities:
 Creation, deletion, updation of files and directories
 Backup to secondary storage
 File Manipulation

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 Operating System Components
4. I/O System Management
 It includes Hardware
 Drivers required to operate I/O device
 Activities involve in handling I/O device called I/O device
management

 Activities:
 Performing Buffering, Caching and Spooling
 Memory management of devices
 Effective utilization of devices
 Driver Support and hiding complexity of hardware

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 Operating System Components
5. Secondary Storage Management
 It includes CD, DVD, Floppy, Pen Drive, Hard Disk
 Security mechanism is required
 Activities involve in handling device called management.

 Activities:
1 Managing the free space available on the secondary-storage
device.
2 Allocation of storage space when new files have to be written.
3 Scheduling the requests for memory access.

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 Operating System Components
6. Networking Management
 Computers are connected to each other for sharing information
is called network
 Protocol is used
 Activities involve in networking called networking management

 Activities:
 Mechanism to share data or resource
 Mechanism to connect computers to each other
 Providing security and permissions
 Mechanism to detect fault over network

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 Use of Operating System Tools

1. User Management
 Operating System can be multiuser or
single user.
 In case of multiple users, the levels of
rights and privileges can be different.
 So operating system needs to keep log
of everything related to the user. It could
be even login and logout times.
 Operating System provides tools to
create users, modify them or even
delete them from the system.
 It even ensures required and limited
access to the system.
 Use of Operating System Tools
2. Security Policy
 Every Operating System has standard
security policies. Implementation of
most of the security policies depends
on the organization.
 Operating System Security policy helps
in protecting systems from various
threats to the system, malware,
spyware, ransomware, viruses, worms
and many more.
 Security policies provide all possible
preventive measures and techniques to
keep Operating System safe.
 Use of Operating System Tools
2. Security Policy
 Major areas where Operating System
Security policies used are-
 System updating or patching system
regularly.
 Software installation or updating of
various antiviruses.
 Firewall installation and management of
incoming and outgoing traffic on
networks.
 Provide security to users account.
 Deciding what kind of data, users and
hardware is vital in the system.
 Use of Operating System Tools

3. Device Management
 Device Management is needed for smooth
functioning of computer system.
 Operating System communicates and
does coordination among devices.
 It includes
 Keep track of present devices
 Resources/Device allocation.
 Choose efficient ways to allocate devices
to different programs or processes.
 Deallocate the devices.
 Use of Operating System Tools

4. Performance Monitor
 Performance monitor supervises
performance of the system.
 It monitors different activities like
memory usage and CPU utilization
 It also monitors performance of the
hardware, software and
applications.
 It analyses the different problems in
the system and can find out by
monitoring function.
 Use of Operating System Tools
5. Task Scheduler
- Throughout the lifetime of process it migrates or
travels to the various scheduling queues.
Schedulers - An OS should select processes for scheduling purposes
from these queues in some manner. The selection
Long Term Short Term
procedure is done by schedulers.
Scheduler Scheduler
- The scheduler which picks up job from this pool and
(Job Scheduler) (CPU Scheduler)
loads into main memory for execution is called long
term scheduler or job scheduler.
- There is another scheduler which selects the jobs or
processes which are ready to execute from this pool
and allocates the CPU to one of them is called Short
term Scheduler or CPU Scheduler