Working with the Command-Line Interface

© 2012 The McGraw-Hill Companies, Inc. All rights reserved

Mike Meyers’ CompTIA A+® Guide to

Managing and Troubleshooting PCs

Fourth Edition

Working with the Command-Line Interface

Chapter 18




Fourth Edition

Overview

• In this chapter, you will learn how to

– Explain the operation of the command-line interface

– Execute fundamental commands from the command line

– Manipulate files and folders from the command line




Fourth Edition

Historical/Conceptual

• IBM invented the PC in the late ‘70s but needed an operating system.– Digital Research had an OS but turned them down– IBM went to a small company (Bill Gates at

Microsoft) that had created BASIC.– Microsoft had never written an OS but accepted

the challenge.• Gates found an OS called Quick-and-Dirty-Operating-

System (QDOS) and purchased it from the person who wrote it.

• Microsoft released it as MS-DOS V 1.1 (Microsoft Disk Operating System).

• MS-DOS 6.22 ultimately released in 1994.• DOS used a command-line interface.




Fourth Edition

Deciphering the Command-Line Interface

220-802




Fourth Edition

Command-Line Interface (CLI)

• How does a command-line interface work?– It begins with a prompt indicating the computer is

ready to do something (such as C:\>).– The user types in a command and presses ENTER.– The command is executed.– A new prompt is displayed—ready for the next

command.– CLI executes commands just as the Windows GUI

does.• In CLI, you type the command and press ENTER.• In GUI, you point and click to execute commands.




Fourth Edition

Command-Line Interface (continued)

Figure 1: Contents of C: directory from the command line

Figure 2: Contents of C: in Computer—Icon view




Fourth Edition

Command-Line Interface (continued)

Figure 3: Selecting Details view in Computer

Figure 4: Contents of C: in Computer—Details view




Fourth Edition

Accessing the Command Line

• Use the Run dialog box or Start Search text box– Start | Run– Type cmd

(or)– Type command– Either runs the

cmd.exe executable program found in %systemroot%\system32

• You can also access the command line through the Start | All Programs menu.

Figure 5: Type cmd in the Run dialog box to open a command-line interface window in Windows XP.




Fourth Edition

Accessing the Command Line (continued)

Figure 6: The command-line interface window with a C:\ prompt

Figure 7: The Windows Vista/7 command-line interface window




Fourth Edition

The Command Prompt

• The command prompt is always focused on a specific folder.– Commands operate on the files and folders in the

folder on which the command line is focused.– You can first focus on the drive and folder where

you want to work to make commands simpler.

Figure 8: Command prompt indicating focus on the C:\Diploma\APLUS\ folder




Fourth Edition

Filenames and File Formats

• Each program or piece of data is stored as a file on the drive.

• Filenames have two parts:– Filename

• In DOS, up to 8 characters long– Extension

• In DOS, up to 3 characters long• Optional

• The filename and extension are separated by a dot– Called the 8.3 naming system

• These characters cannot be used today:/ \ < > | : " * ?




Fourth Edition

Filenames and File Formats

• Windows does not restrict the filename to 8.3 (it can be up to 255 characters).– To be backward-compatible with DOS, you need to

follow the 8.3 standard.– Windows creates two filenames for every file to

ensure backward-compatibility.

• The extension tells the computer the type of file.– .exe, .doc, .xls– .gif, .jpg, .png– .chm (help file)




Fourth Edition

Filenames and File Formats (continued)

Figure 10: One file has no extension.

Figure 9: What kind of file is the one on the lower right?




Fourth Edition

File Formats

• All files are written in binary format.– Different programs have unique methods of reading and

writing, so one program may or may not understand files from another program.

– Need for a universal format• American Standard Code for Information

Interchange (ASCII) used for text– First universal file format– Defines 256 8-bit characters

• Unicode– Uses 16-bit code to cover every character for the most

common languages– First 256 characters are the ASCII characters




Fourth Edition

ASCII Character Chart

Figure 11: ASCII characters




Fourth Edition

Folders and Files

• Folders and files must be unique.– Can’t use the same name in the same folder.

• C:\ represents the root directory of C.

• To describe a subfolder, add the name of the folder:– C:\TEST

• The location of a file is called the path.– The path of C:\test\file.txt is C:\test




Fourth Edition

Directory Tree




Fourth Edition

Mastering Fundamental Commands




Fourth Edition

Structure: Syntax and Switches

• The command line requires the exact syntax for each command.

• Type the name of the command and the desired or allowed switches, and then press ENTER to execute the command.– Switches modify the behavior of the command.– Multiple switches may be allowable.– DIR /W /P

displays the directory in wide mode and one page at a time.




Fourth Edition

Help

• Help with any command is readily available in one of three ways.– HELP gives a one-line description of the command.– HELP [command] gives specific help for the

command.– [Command] /? gives specific help for the command.




Fourth Edition

dir Command

• The dir command lists the contents of a particular directory– The dir /w command lists only the folder

and file names

Figure 12: Results for dir in a user’s folder




Fourth Edition

dir Command Switches

Figure 13: Typing dir /? lists all possible switches for the dir command




Fourth Edition

Directories: cd Command

• The cd (or chdir) command is used to change the focus to a different directory.

• The cd\ command is used to return to the root directory.

• Type cd [folder name] and then press ENTER to change focus to that folder or directory.

• Type cd.. and press ENTER to go up one directory.

• To switch between drives, type the drive letter followed by a colon, and then press ENTER.– C:– D:




Fourth Edition

Making and Removing Directories

• The md (or mkdir) command is used for creating a directory.

• The del command is used for deleting files, and the rd (rmdir) command is used for deleting directories and subdirectories.

• rd /s will removed populated folders and their contents.




Fourth Edition

Lab – Making and Removing Folders

1. Change focus to root2. Create three folders

– class– docs– backup

3. Create a subfolder in backup– temp

4. Delete rd the temp folder5. Use dir to check each step




Fourth Edition

Running a Program

• To run a program– Change the prompt focus to the directory where

the program is stored: cd c:\windows\system32

– Type the filename with or without its extension and press ENTER:

edit.com




Fourth Edition

Running a Program (continued)

Figure 15: Running mem in Windows Vista 32-bit

Figure 14: The mem.exe program displayed in the System32 folder




Fourth Edition

Working with Files




Fourth Edition

Start at the Root

• What's in your root directory?

• Double-click C: drive in My Computer.– Hey! Where are the Windows system files, like

NTLDR and BOOT.INI?– Could go to Folder Options and display hidden and

system files, or could go to the prompt.

• DIR /P still doesn’t show the system files, so we need a new tool.




Fourth Edition

Working with Files

• Attributes (H, R, S, A) are special values assigned to a file:– Hidden: hides the file– Read-only: protects a file

from being deleted or modified– System: identifies system files– Archive: identifies files that

have not been backed up

• The attrib.exe program is used to inspect and change file attributes.




Fourth Edition

attrib

• attrib can be used to change the attributes.

– Use + to add attribute.– Use – to remove attribute.

attrib +r ailog.txt Makes the file read only.

attrib –h ailog.txt Makes the file no longer hidden.




Fourth Edition

Working with Files

• Wildcards– Wildcards are special characters that enable

commands to act on more than one file at a time.– The * represents any number of characters.– The ? represents a single character.

dir *.txt Lists all files that end in .txt

dir *.?xt Lists all files that end in xt




Fourth Edition

Working with Files (continued)

• ren is used to rename files.

• del and erase are used to delete files.

• copy is used to make a copy of the file in a new location.

• move is used to move the file to a new location.

• xcopy is used when working with multiple directories.




Fourth Edition


Figure 17: Success at lastFigure 16: Rename failed me




Fourth Edition


• robocopy is a newer command included in Windows Vista and 7.– Allows many different functions beyond copy and

xcopy:– Copies encrypted files– Duplicates source directories– Allows administrators to copy even when denied

permissions to files– Resumes copying after an interruption




Fourth Edition

Mike’s Five-Step copy/move Process

1. Point the command prompt to the directory containing the files to be copied or moved.

C:\>cd \docs2. Type copy or move and a space.

C:\DOCS>copy 3. Type the name(s) of the file(s) to be

copied/moved and a space.C:\DOCS>copy *.doc

4. Type the path of the new location for the files.

C:\DOCS>copy *.doc c:\Steam5. Press ENTER.




Fourth Edition

Useful Utilities

• chkdsk (/f /r)– Runs the command-line version of error-checking.– Run to recover from accidental shutdown, such as

during a disk defragmentation.• format

– Normally done from the GUI, but can do this quickly from the CLI.

– format x: /q is a great way to wipe a drive.• hostname

– Used to display the name of your computer, also known as the hostname.




Fourth Edition

Useful Utilities (continued)

Figure 19: Using format /? at the command prompt

Figure 18: The chkdsk /f /r utility and switches on a locked drive




Fourth Edition

Useful Utilities (continued)

• sfc– System File Checker helps restore Windows files.– sfc /scannow from a command prompt

Figure 20: Checking sfc options with sfc /? at a command prompt




Fourth Edition

Beyond A+




Fourth Edition

Using Special Keys

• F1 function key brings back the previous command one letter at a time.

• F3 function key brings back the entire command at once.

• Arrow keys– You can also use the arrow keys (up and down) to

scroll through commands.– Arrow keys (left to right) enable you to edit

commands.




Fourth Edition

compact Command

• compact– Displays or alters the compression state of files.– compact /c

Figure 21: The compact command with no switches




Fourth Edition

compact Command (continued)

Figure 23: The contents of C:\Compact have been

compressed

Figure 22: Typing compact /c compresses the contents of

the directory




Fourth Edition

compact Command (continued)

Figure 24: Typing compact /u "Session 1.ppt" decompresses only that file




Fourth Edition

cipher Command

• cipher– Displays or alters the encryption state of files.– /e specifies encryption operation.– /a says to apply it to the files as well as the

directory.

Figure 25: Typing cipher /e /a encrypts the contents of the directory




Fourth Edition

cipher Command (continued)

Figure 27: Typing cipher /d /a

dsc_4255.dng decrypts only that fileFigure 26: The cipher command confirms

that the files were encrypted




Fourth Edition

PowerShell

• PowerShell– Introduced in Windows XP and improved in

Windows 7.– Powerful addition to traditional command-line

interface.– Uses powerful tools called cmdlets.– Syntax is slightly more complex than regular

command-line use.– In Windows 7, type powershell in search bar.– In XP/Vista, you must download from Microsoft and

have the .NET 2.0 framework installed.




Fourth Edition

PowerShell (continued)

Figure 28: Simple commands in PowerShell

Documents

Working with the Command-Line Interface