Command Line Interface

1
Command Line Interface
2
Lecture Objectives

• Explain the operation of the command line
  interface
• Execute fundamental commands from the command
  line interface
• Manipulate files and folders from the command line

3
How does the Command Line Work?

• Similar to Instant Message conversation with
  computer
• The prompt indicates that the computer is ready
  to receive a command
• Command is typed and ENTER is pressed
• PC executes command
• Prompt is displayed, indicating that the computer
  is waiting for the next command

4
Accessing the Command Line

• Run dialog box
• Start menu under Programs Accessories
• Win 9x/Me link is named MS-DOS prompt
• Win NT, 2000, XP link is called Command Prompt
• To close command line interface
• Type Exit at command line and press enter
• Close the window

5
Command Prompt

• VERY IMPORTANT
• The command prompt is always focused on a
  specific folder.
• Any commands executed are performed on the files
  in the folder on which the prompt is focused.
• Examples C\gt root directory of C drive
• C\Diploma\APLUSgt
• You must focus the prompt on the drive and folder
  where you want to work

6
Filenames and File Formats

• In Windows, each program and piece of data is
  stored as an individual file
• Each file has a name, stored with the file on the
  drive
• Names have 2 parts filename and extension

7
Eight-dot-Three naming system

• File name cannot be more that 8 chrs
• Extension can be up to 3 chrs, OPTIONAL
• Following chrs cannot be used in filename or
  extension
• / \ , ? And division symbol

8
Windows naming rules

• All versions starting with Win 9x are not limited
  be 8.3
• Filenames up to 255 chrs
• Win 9x has backward compatibility with DOS by
  creating 2 names for every file, 8.3 name and a
  long file name if necessary

9
File extensions

• Describes the type or function of the file
• COM command, EXE executable
• Anything that is not a program is a data file
  used by a program
• Extension of a data file indicates which program
  uses that data file
• .DOC MSWord, .PPT PowerPoint
• Graphic file extensions represent the graphic
  standard used to create the image
• .JPEG Joint Photographic Experts Group

10
File Formats

• All files stored on hard drive in binary format
• Every program is unique in the way it reads and
  writes this binary data
• Each unique way of binary organization is known
  as a file format
• One program cannot read another programs files
  unless it can convert the other programs format

11
Drives and Folders

• To execute commands from the command line, must
  focus the prompt at the specific drive and folder
  that contains the files or program with which you
  want to work
• At boot, Win assigns letters to drives and drive
  partitions

12
Hierarchical Directory Tree

• All files are put in groups called folders
• Any file not in a folder within the tree is said
  to be in the root directory
• A folder inside another folder is called a
  subfolder
• Any folder can have multiple subfolders

13
Hierarchical Directory Tree

• Hard drive is represented by C
• Root directory is indicated by \, C\
• Subdirectories/Subfolders are indicated by adding
  \ and the directory name
• Exact location of a file is known as its PATH

14
Fundamental Commands

• ALL commands use similar structure and execute in
  the same way
• Name of command , target of command followed by
  any switches (extra numbers or letters at the
  end)
• Typing the command followed /? Displays help menu
  describing syntax and possible switches

15
DIR Command

• Contents of the directory where the prompt is
  focused
• Lists the following
• Filename
• Extension
• File size in bytes
• Creation date/time
• DIR/W command shows you only the file names
• DIR/? Shows the help menu

16
CD Command (Directories)

• Change focus of command prompt to a different
  directory
• CD\ followed by directory name
• If directory does not exist, error message
• Invalid Directory
• The system cannot find the path specified
• Return to root directory by typing CD\

17
Moving Between Directories

• CD NOT used to move between drives
• Type drive letter followed by colon
• If drive does not exist
• Invalid drive specification
• The system cannot find the specified drive

18
Making Directories

• To make a directory
• To make a directory called QUAKE3 under root
  directory C\gtMD QUAKE3, press ENTER
• If command is successfully executed, the command
  prompt will be displayed
• Use DIR to verify that directory was created

19
Removing Directories

• Reverse of MD
• Go to directory that contains the subdirectory
  you want to delete
• Execute RD command
• RD will not delete directory if it contains
  subdirectories or files

20
Running a Program

• Change focus of prompt to the folder where
  program is located
• Type name of program
• Press ENTER

21
Working with Files

• All files have 4 basic attributes
• Hidden
• Read-only
• System
• Archive
• Refer to photocopy for specific example of
  attribute command

22
Renaming Files

• REN or RENAME command (refer to photocopy for
  example)

23
Delete Files

• Use DEL command
• Careful! No recycle bin.
• Erased file can only be recovered using Norton
  Unerase
• Can delete multiple files using wild cards

24
Copying and Moving Files

• Focus prompt on directory containing the file or
  folder to be copied
• Type COPY or MOVE and a space
• Type name(s) of the file(s) to be copied/moved
  and a space
• Type the path of new location for the files
  (Refer to example on photocopy)

25
The Software Core
26
A Short History of MS-DOS
27
Understanding DOS

• All versions were built for a specific class of
  CPU.
• MS-DOS never overcame critical limitations.
• All versions used a command-line interface.
• You must use the DOS prompt to set up a new
  system or hard disk drive.

28
DOS Boot Sequence and Files

• Three core programs
• IO.SYS
• MSDOS.SYS
• COMMAND.COM
• Two optional startup files
• CONFIG.SYS
• AUTOEXEC.BAT

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Summary of Steps in Booting the System

1. The power-on self test (POST) runs and invokes
   the operating system (OS).
2. The read-only memory basic input/output system
   (ROM BIOS) looks for an OS and checks for IO.SYS
   and MSDOS.SYS.
3. The OS processes CONFIG.SYS, if present.
4. COMMAND.COM is loaded.
5. The OS processes AUTOEXEC.BAT, if present.
6. COMMAND.COM presents the active-drive prompt.

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The DOS File System

• The file is the primary unit of data storage.
• Files are organized into directories.
• File and directory names can be up to eight
  characters long, followed by a period and a
  three-character extension.
• Some universal extensions are .exe, .com, .sys,
  .bat, .txt, .doc, and .drv.
• File and directory names are not case-sensitive.

31
The Evolution of Microsoft Windows

• Early versions presented a graphical user
  interface (GUI) for MS-DOS.
• Microsoft Windows 3.11 was the last 16-bit OS and
  the most well known version.
• Microsoft Windows 95 was the first 32-bit
  version.
• All applications designed for Windows have
  standard interfaces.
• Multitasking allows users to have more than one
  application open.

32
Operating Modes

• Real mode could address only 1 MB of random
  access memory (RAM).
• Standard mode allowed programs to run in
  protected mode.
• In protected mode, programs could address up to
  16 MB of RAM.
• 386 enhanced mode could address up to 4 GB
  of RAM.
• Certain applications included a Windows runtime
  version.

33
Windows Resource Management
34
Memory Paging and Virtual Machines

• Virtual memory is an area on the hard disk drive
  (called a swap file) that the system uses to
  store program code temporarily.
• Virtual machines (VMs) allow multiple programs to
  operate.
• DOS programs run individually in separate VMs.

35
Windows Operating Systems

• Microsoft Windows for Workgroups 3.11 is an
  upgrade to Microsoft Windows 3.1.
• Windows 95, Microsoft Windows 98, and Microsoft
  Windows Me can be networked easily.
• Microsoft Windows NT is designed for networking.
• Microsoft Windows 2000 replaces Windows NT.
• Upgrading to Windows NT or Windows 2000 could
  present compatibility problems with some hardware
  and applications.

36
The COMMAND Command

• MS-DOS uses a text-based command-line user
  interface.
• A text-based interface requires no drivers
  because display functions are built in.
• COMMAND.COM provides the user interface.

37
Working with the Prompt

• Typing PROMPT /? or HELP PROMPT provides help
  information.
• DOS HELP returns information on customizing the
  prompt and the information that appears.

38
Internal and External Commands

• External commands exist as separate files.
• Windows has its own set of system utilities.
• Internal commands are contained within
  COMMAND.COM.
• Command mode requires typing a command instead of
  clicking an icon.

39
DOS Mode Navigation and File Management

• The DOS file system uses a tree structure.
• A fully qualified path is the list of directories
  from the root to the file.
• The DIR command displays the contents of the
  current or a specified directory.
• DOS does not support Windows long filenames.
• The MD command creates a new directory.

40
The PATH Command

• PATH allows you to display and change the search
  path.
• PATH appends the old path to the new path.
• Programs in path directories can be run from any
  location on the computer.

41
Creating a Batch File

• A batch file is an executable file that runs a
  series of existing commands or applications.
• Commands listed in the file are executed in
  sequence.
• Any executable that can be run from the prompt
  can be included in a batch file.

42
Renaming a File

• The RENAME or REN command allows you to rename a
  file.
• The CD command allows you to change directories.
• The CLS command clears the screen.

43
Using Edit
44
Summary of DOS Terminology
45
CONFIG.SYS Commands

• MOUSE.SYS
• NUMLOCK
• SHELL
• SWITCHES

• BUFFERS
• COUNTRY
• DEVICE
• DEVICEHIGH
• DOS

• FCBS
• FILES
• INSTALL
• LASTDRIVE

46
AUTOEXEC.BAT Commands

• SET
• SHARE
• SMARTDRV

• DOSKEY
• ECHO
• KEYB
• MOUSE.EXE

• PATH
• PAUSE
• PROMPT

47
File System Basics

• The file system organizes data on the storage
  medium.
• Different media require different file systems.
• File systems define naming conventions, file
  size, and media capacity.
• Magnetic media employ several different file
  systems, depending on the OS.

48
Key File System Terms

• Partition table
• Primary partition
• Sector
• Track
• Volume

• Filename
• Folder
• Format
• Low-level format
• Master boot record

• Block
• Boot disk
• Boot sector
• Cluster
• Dual boot
• Encryption

• End-of-file (EOF) marker
• File
• File allocation table (FAT)
• File format
• File handle
• File locking

49
Comparing and Choosing File Systems

• Decision factors
• Dual boot requirement
• Number and size of hard disk drives
• Size of partitions
• Need to support legacy applications
• Need for advanced features such as security

50
FAT-Based File Systems

• All modern PCs can use FAT.
• FAT organizes files by listing them in a table.
• Two copies of the table are maintained on the
  media.
• FAT was developed for and is still used by floppy
  disk drives.
• There are three versions FAT12, FAT16, and
  FAT32.

51
FAT16 and FAT32 Compared and Contrasted
FAT16
FAT32

• High compatibility
• Use of MS-DOS bootable floppy disk
• Performance advantage on small volumes
• Manual intervention to use FAT copy
• No backup of boot sector
• 2-GB volume limit
• Better performance when operating in real mode or
  safe mode
• Dual boot with Windows NT and Windows 98
• 8.3 filenaming limit

• Limited compatibility
• No use of MS-DOS bootable floppy disk
• More efficient allocation of disk space
• Automatic use of FAT copy if needed
• Automatic backup of boot sector
• Support of 32-GB volumes
• Faster load times for applications and large data
  files
• No dual boot with Windows NT and Windows 98
• Support of filenames up to 255 characters

52
The NT File System (NTFS)

• Was introduced with Windows NT
• Supports long filenames and is optimized for
  multiuser environments
• Provides file and folder level security
• Is more reliable than previous file systems
• Is not completely supported under Windows NT

53
Advantages and Disadvantages of NTFS

• Advantages

• Disadvantages

• Supports volumes up to 2 terabytes (TB)
  
• Maintains a recovery log
• Has no limit on number of entries at root
• Allows faster file access
• Supports disk quotas (Windows 2000)
• Supports file and folder compression
• Supports file and folder security

• Does not allow accessing NTFS volumes under
  MS-DOS, Windows 95, or Windows 98
• Does not allow using NTFS volumes as a primary
  partition for dual booting MS-DOS, Windows 95, or
  Windows 98
• Could decrease performance on volumes smaller
  than 400 MB

54
File System Size Limitations

• Different OSs handle cluster size differently.
• Under FAT volumes, drives smaller than 16 MB
  are formatted as FAT12.
• MS-DOS, Windows 95, and Windows 98 cannot access
  FAT16 volumes larger than 2 GB.

55
File System Security

• FAT attributes on FAT file systems
• FAT has attributes that can protect files from
  being overwritten or viewed.
• Attributes can be set by using the ATTRIB
  DOS-mode command, or by right-clicking a file in
  Windows and selecting the Properties option.
• NTFS file and folder security
• NTFS uses permissions to determine who can access
  the file or folder.
• Permissions are set by using the Security tab for
  the file or folder.

56
Chapter Summary

• An OS is the interface between the hardware and
  the user.
• All OSs have a user interface, memory, and file
  management.
• Technicians need to know how to perform command
  prompt operations.
• Technicians who work with older OSs must
  understand MS-DOS and DOS startup files.
• Internal and external commands can be used to
  configure and troubleshoot.
• FAT32 has several enhancements over FAT16.
• NTFS supports file and folder security,
  compression, and disk quotas.