Download CEG 210 FALL 2010 Chapter 9 Network Operating Systems

CEG 2400 FALL 2012
Linux/UNIX
Network Operating Systems
UNIX and Linux
• Popular NOSs
– UNIX/Linux operating system comes in many
varieties, or distributions
– Provide resource sharing
– Older
• UNIX develop in 1969
– Most Internet servers run UNIX
• Some difficulty to master UNIX
– Not controlled, distributed by single manufacturer
– Some version nonproprietary and freely distributed
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Varieties of UNIX
• Many varieties (flavors, distributions)
– Share several features
• UNIX operating system
– Divided into two main categories
• Proprietary
• Open source (Linux, many varieties, free)
– Ubuntu, OpenSUSE, etc
• Can be GUI or GUI-less
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UNIX and Linux
Proprietary UNIX
• Available only by purchasing licensed copy
• Vendors
– Apple Computer: Mac OS X Server
– Sun Microsystems: Solaris
– IBM: AIX
– Novell: SUSE
– HP: hp-ux
– Red Hat
– Others
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UNIX and Linux operating system
• UNIX and Linux operating system share the following
features:
– The ability to support multiple, simultaneously logged-on
users
– The ability to coordinate multiple, simultaneously running
tasks (or programs)
– The ability to mount —or to make available—disk
partitions upon demand
– The ability to apply permissions for file and directory
access and modification
– A uniform method of issuing data to or receiving data from
hardware devices, files, and running programs
– The ability to start a program without interfering with a
currently running program
UNIX and Linux operating system
• UNIX and Linux operating system share the
following features: (con’t)
– Hundreds of subsystems, including dozens of
programming languages
– Programs necessary for routing, firewall protection,
DNS services, and DHCP services
– Source code portability, or the ability to extract code
from one UNIX system and use it on another
– Window interfaces that the user can configure, the
most popular of which is the X Window system
UNIX and Linux operating system
• UNIX and Linux operating system share the
following features: (con’t)
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TCP/IP protocol suite
Applications to support networking infrastructure
Support non-IP protocols
Operates over many different network topologies,
physical media
• Efficiently and securely handle growth, change, stability
• Source code used, thoroughly debugged
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UNIX Multiprocessing
• UNIX and Linux
– Support processes and threads
– Allocate separate resources (memory space) to each
process
• When created
• Manage access to resources
• Advantage: prevents one program from disrupting system
– Support symmetric multiprocessing
– Different versions support different number of
processors
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The UNIX Memory Model
• Use physical, virtual memory efficiently
• Allocate memory area for each application
– Share memory between programs when possible
• Use 32-bit addressing scheme
– Programs access 4 GB memory
• Most systems also run on CPUs employing 64bit addresses
• Virtual memory
– Disk partition or file
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The UNIX Kernel
• Kernel
– Core of all UNIX and Linux systems
– Loads into memory
– Primary function is to coordinate access to
computer’s hardware
• Kernel module
– File containing instructions for performing specific
task
• EX. Reading data from and writing data to hard drive
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The UNIX Kernel
UNIX System File and Directory
Structure
• Hierarchical file system
– Disk directories may contain files, other
directories
• /boot directory: kernel, system initialization
files
• /sbin directory: applications, services
• /var directory: variable data
• /home directory: created for new users
• Some versions have other directories
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UNIX System File and Directory
Structure (cont’d.)
UNIX file system hierarchy
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Disk File Systems
• Organizing, managing, accessing files
– Through logical structures, software routines
• Linux native file system type
– ext4: “fourth extended” file system
– There are so many others
• Solaris native file system
– UFS (UNIX file system)
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UNIX and Linux
Network File Systems
• Similar to Windows shares
– Attach shared file systems (drives)
• From Windows, other UNIX servers
– Share files with users on other computers
• UNIX and Linux popular remote file system type
– Sun Microsystems’ NFS (Network File System)
• Open source application implementing Windows
SMB, CIFS file system protocols
– Samba
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A UNIX and Linux Command Sampler
• Many system administrators prefer command
line
• GUI executes commands
– Responds to mouse clicks
• Command interpreter (shell)
– Accepts keyboard commands and runs them
• Man pages (manual pages)
– Full documentation of UNIX command
– Similar to windows help
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A UNIX and Linux Command Sampler
• Commands function like sentences
• Significant UNIX and Windows command-line
interface difference
– Character separating directories
• Windows separator character: ( \ )
• UNIX separator character: ( / )
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19 commands
Commonly used UNIX
A UNIX and Linux Command Sampler
• Most frequently used UNIX command
– ls
– Provides file information
• Stores in file inode (information node)
– ls –l command
• Access permissions field
• Files type designations
• Pipe
– Direct one command output to input of another
command
– Unix: vertical bar ( | )
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Example of output from ls -l
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Anatomy of ls –l output
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Summary
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Many varieties
Proprietary vs Open source
Many common features
Memory model
Kernel
File System
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End of Linux/UNIX
Questions