Present By:- aBhay Panchal What is Operating System

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Bog'liq
Unix

UNIX Interfaces

Command Line Interface

You also have access to some UNIX servers as well.

You can logon from virtually any computer that has internet access whether it is Windows, Mac, or UNIX itself.

In this case you are communicating through a local terminal to one of these remote servers.

All of the commands actually execute on the remote server.
It is also possible to open up graphical applications through this window, but that requires a good bit more setup and software.

Process Management

Operating system functions executes within user process.
2 modes of execution

User mode
Kernel mode

2 types of processes are available

System processes (Execute OS code)
User processes (Execute user program code)

System call is used to transfer form user mode to system mode.

Process State in UNIX

User running Execute in use mode
Kernel running Execute in kernel mode

Ready to run in memory

ready to run as soon as the kernel schedules it

Asleep in memory

unable to execute until event occurs.

Ready to run, swapped

process is ready to run, but the swapper must swap process into main memory before kernel can schedule it to execute.

Process State in UNIX

Sleeping , swapped
Preempted does
Created
Zombie

a process is awaiting an event and has been swapped to secondary storage.
process is returning from kernel to user mode, but the kernel preempts it and
a process switch to schedule another process
process is newly created and not yet run.
process no longer exists, but it leaves a record from its parent process to collect.

Process Scheduling Queues

Job queue
Ready queue
Device queues.

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