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Pertemuan 24Sistem Operasi Unix

Matakuliah : T0316/sistem Operasi

Tahun : 2005

Versi/Revisi : 5

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Learning Outcomes

Pada akhir pertemuan ini, diharapkan mahasiswa

akan mampu :• mendemonstrasikan sistem operasi Linux, dari

manajemen proses, memory, file sampai dengan I/O (C3)

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Outline Materi

• Sejarah Unix• Overview Unix• Shell• Program Utiliti• Proses pada Unix• System Call• System memory dan I/O pada Unix

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LINUX

• Sejarah Unix– Unics– PDP 11 Unix– Portable Unix– Barkeley Unix– Standar Unix– MINIX– LINUX

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Overview of Unix

• UNIX Goals– UNIX is an interactive system designed to

handle multiple processes and multiple users at the same time.

– It was designed by programmers, for programmers, to use in an environment in which the majority of the users are relatively sophisticated and are engaged in software development projects

– Extensive facilities to work together

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Interfaces to UNIX

The layers of a UNIX system.

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UNIX Kernel

Approximate structure of generic UNIX kernel

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Booting UNIX

The sequences of processes used to boot some systems

cp

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SHELL

• Program Login

• Prompt

• Command

• Argument

• Redirect

• Pipe

• Shell Script

• Background process

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Contoh

• cp src dest• head –20 file• ls x.c y.c z.c• sort < in > out• sort < in > temp; head –30 < temp; rm temp• sort < in | head –30• grep ter *.t | sort | head –20 | tail –5 > foo• wc –l < a > B &• sort < x | head &

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Program Utiliti

• Manipulasi file dan direktori

• Filter

• Tool untuk pengembangan program

• Text processing

• Sistem administrator

• dll

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UNIX Utility Programs

A few of the more common UNIX utility programs required by POSIX

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Process pada Unix

• Sistem multiprogramming• Daemonds• Cron daemonds• System fork• Process parent• PID• Pohon process• signal• Group process• UID• Superuser (root)

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System Calls for Process Management

s is an error code

pid is a process ID

residual is the remaining time from the previous alarm

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POSIX Shell

A highly simplified shell

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Implementasi Process

• Process Table (always in memory)– Parameter scheduling– Memory map– Signal– Etc

• User Structure (only in memory when the program is executed)– Machine registers– System call state– File descriptor table– Accounting– Stack kernel

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Handling Memory

• Process A's virtual address space• Physical memory• Process B's virtual address space

Process A Process B

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Sharing Files

Two processes can share a mapped file.

A new file mapped simultaneously into two processes

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Implementation of memory management

• Swapping

Tiga hal yang menyebabkan swapping ke disk

1. Fork

2. BRK (request for memory)

3. Stack increase

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Implementation (2)

Paging in UNIX•Page daemon•Core map information about the contents of page frame

The core map in 4BSD

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Implementation (3)

• Page replacement algorithm Two handed clock – Two pointers– First, it clear the usage bit at the front end, and– Then, check the usage bit at the back hand

• If two hands are kept close together, then only very heavily used pages have their R-bit stay 1 (after being zero-ed by the front hand)