hệ điều hành nguyễn văn hiệp chương ter 10 unix and linux sinhvienzone com

Chapter 10
Case Study 1: UNIX and LINUX
10.1 History of unix
10.2 Overview of unix
10.3 Processes in unix
10.4 Memory management in unix
10.5 Input/output in unix
10.6 The unix file system
10.7 Security in unix
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1


UNIX
User
Interface

The layers of a UNIX system.

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UNIX Utility Programs

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

Approximate structure of generic UNIX kernel
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4


Processes in UNIX

Process creation in UNIX.

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POSIX

The signals required by POSIX.

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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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Threads in POSIX

The principal POSIX thread calls.

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The ls Command

Steps in executing the command ls type to the shell
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Flags for Linux clone

Bits in the sharing_flags bitmap

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UNIX Scheduler

The UNIX scheduler is based on a multilevel queue structure
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Booting UNIX

cp

The sequences of processes used to boot some systems
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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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System Calls for Memory Management

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s is an error code
b and addr are memory addresses
len is a length
prot controls protection
flags are miscellaneous bits
fd is a file descriptor
offset is a file offset
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Paging in UNIX

The core map in 4BSD.

The core map has an entry for each page
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Paging in Linux (1)

Linux uses three-level page tables
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Paging in Linux (2)

Operation of the buddy algorithm.

Buddy algorithm
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Networking

Use of sockets for networking
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Terminal Management

The main POSIX calls for managing the terminal
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UNIX I/O (1)

Some of the fields of a typical cdevsw table
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UNIX I/O (2)

The UNIX I/O system in BSD
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Streams

An example of streams in System V
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The UNIX File System (1)

Some important directories found in most UNIX systems
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