Matakuliah
Tahun
Versi/Revisi
: T0316/sistem Operasi
: 2005
:5
Pertemuan 24
Sistem Operasi Unix
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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
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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
cp
The sequences of processes used to boot some systems 8
SHELL
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Program Login
Prompt
Command
Argument
Redirect
Pipe
Shell Script
Background process
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Contoh
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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
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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
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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 alarm14
POSIX Shell
A highly simplified shell
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Implementasi Process
• Process Table (always in memory)
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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
Process B
• Process A's virtual address space
• Physical memory
• Process B's virtual address space
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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
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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)
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