1. Working with the Command-Line Interface
Chapter 18

2. 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

3. 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.

4. Deciphering the Command-Line Interface
Deciphering the Command-Line Interface

5. 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.

6. Command-Line Interface (continued)
Figure 2: Contents of C: in Computer—Icon view
Figure 1: Contents of C: directory from the command line
From the command line, you’d type a command (such as DIR), and the computer would respond by displaying a screen like the one in Figure 1.
In the Windows GUI, you would open My Computer or Computer and click the C: drive icon to see the contents of that directory. The results might look like Figure 2.

7. Command-Line Interface (continued)
Figure 4: Contents of C: in Computer—Details view
Figure 3: Selecting Details view in Computer
By choosing a different view (see Figure 3), you can make the results look quite a bit like the command-line version, albeit much prettier (see Figure 4).

8. 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.
To close the command-line interface, type exit.

9. Accessing the Command Line (continued)
Figure 6: The command-line interface window with a C:\ prompt
The Windows XP command prompt window (Figure 6), and the Windows Vista/7 command prompt window in Figure 7. Note the difference in user profile naming.
Figure 7: The Windows Vista/7 command-line interface window

10. 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

11. 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:
/ \ < > | : " * ?
Windows Filenames
Windows allows a lot of freedom in filenaming, but it still has a handful of characters that you can’t use for file or folder names:
/ \ [ ] | ÷ + = ; , * ?
Filenames can be up to 255 characters in length.

12. 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)

13. 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?
Figure 9 shows a folder with two identical image files. The one on top shows a thumbnail because Windows recognizes this as a JPEG image; the one on the bottom shows a generic icon because I deleted the extension. Windows’ GUI doesn’t show file extensions by default. Figure 10 shows the contents of that same folder from the command line.

14. 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 bit characters
Unicode
Uses 16-bit code to cover every character for the most common languages
First 256 characters are the ASCII characters

15. Figure 11: ASCII characters
ASCII Character Chart
Have the students open Notepad or Wordpad and have them type some ASCII. Press the ALT key and then press numbers on the keypad. No need for the leading zeroes on the commands (they won’t work, if you add them).
Figure 11: ASCII characters

16. 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
Tech Tip
Directory Trees
Visualizing a directory tree as upside down is helpful, because in geek speak, the trunk, or “root directory,” is spoken of as if it were “above” the folders that divide it up, and those subfolders are spoken of as being “above” the folders into which they are divided. For example, “The file is in the Adobe folder under Program Files.”

17. Directory Tree

18. Mastering Fundamental Commands
Syntax
HELP
DIR CD MD RD

19. 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.

20. 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.
Note that some commands (such as RD, MD, and CD) are internal—they come as part of the command-line interpreter, cmd.exe. Others require their own executable—these are called external commands.

21. Figure 12: Results for dir in a user’s folder
dir Command
The dir command lists the contents of a particular directory
The dir /w command lists only the folder and file names
Tech Tip
Error Messages Are Good!
Let’s talk about errors in general for a moment, not just command-prompt errors like “Invalid directory,” but any error, including Windows errors. Many new computer users freeze in horror when they see an error message. Do not fear error messages. Error messages are good! They will save you. Seriously, think how confusing it would be if the computer didn’t tell you when you messed up. Error messages tell us what we did wrong so we can fix it. You absolutely cannot hurt your PC in any way by typing the DIR or CD commands incorrectly. Take advantage of this knowledge and really experiment. Intentionally make mistakes to familiarize yourself with the error messages. Have fun. Learn from errors.
Figure 12: Results for dir in a user’s folder

22. dir Command Switches
Figure 13: Typing dir /? lists all possible switches for the dir command

23. 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:
The Windows command-line interface almost never tells you that a command has been performed successfully. But be assured it will complain when you do something wrong! The old adage is, “DOS never pats you on the back, but it will slap you in the head!”

24. 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.
The RD command in Windows will delete populated directories—that is, directories containing files or subdirectories. Use the /S switch: Type RD /S and the directory name.

25. Lab – Making and Removing Folders
Change focus to root
Create three folders
class
docs
backup
Create a subfolder in backup
temp
Delete rd the temp folder
Use dir to check each step

26. 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
By and large, you can’t run Windows GUI-based applications within a command-line environment. Most will simply pop open in their own window, just as if you opened them from the Start menu. Try typing SYSEDIT at the command prompt within Windows and see what happens!

27. Running a Program (continued)
Figure 15: Running mem in Windows Vista 32-bit
Figure 14: The mem.exe program displayed in the System32 folder
Go to the C:Windows\System32 folder—the exact name of this folder varies by system. Type dir /p to see the files one page at a time. You should see a file called mem.exe if you’re running a 32-bit version of Windows (see Figure 14).
To run the mem.exe program, just type the filename, in this case mem, and press ENTER (see Figure 15). Note that you do not have to type the .exe extension, although you can.

28. Working with Files

29. 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.

30. 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.

31. 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.

32. 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

33. 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.

34. Working with Files (continued)
Figure 17: Success at last
Figure 16: Rename failed me
You’ll get an error message (see Figure 16) if you try to rename to a filename with spaces in it. You can use more complicated names (including spaces) by putting them in quotation marks. Figure 17 shows the same command that failed but now succeeds because of the quotation marks.

35. Working with Files (continued)
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

36. Mike’s Five-Step copy/move Process
Point the command prompt to the directory containing the files to be copied or moved.
C:\>cd \docs
2. 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:\Steam
5. Press ENTER.

37. Useful Utilities chkdsk (/f /r) format hostname
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.

38. Useful Utilities (continued)
Figure 18: The chkdsk /f /r utility and switches on a locked drive
For example, if you run chkdsk /f /r and chkdsk does not consider your drive unlocked, you will receive a “cannot lock current drive” message, meaning that another process has the drive locked and is preventing chkdsk from locking the drive itself. After this, chkdsk presents you with the option to run it the next time the system restarts (see Figure 18).
The very best way to familiarize yourself with the format command and its available switches is simply to enter format /? from the command prompt. Your results should be similar to those displayed in Figure 19.
Figure 19: Using format /? at the command prompt

39. 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

40. Beyond A+

41. 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.
You can use the up and down arrow keys on the keyboard to scroll through previously typed commands.

42. Figure 21: The compact command with no switches
Displays or alters the compression state of files.
compact /c
Figure 21: The compact command with no switches

43. compact Command (continued)
Figure 23: The contents of C:\Compact have been compressed
Figure 22: Typing compact /c compresses the contents of the directory
If you enter the COMPACT command with the /c switch, it compresses all of the files in the directory, as shown in Figure 22.
Typing compact again shows you the directory listing, and now there’s a C next to each filename, indicating that the file is compressed (see Figure 23).

44. compact Command (continued)
To decompress a file, you must specify the decompression operation, using the /u switch and the name of the file you want decompressed, as shown in Figure 24.
Figure 24: Typing compact /u "Session 1.ppt" decompresses only that file

45. Figure 25: Typing cipher /e /a encrypts the contents of the directory
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 shows two steps in the process. Like the COMPACT command, the CIPHER command simply displays the current state of affairs when entered with no switches. In this case, it displays the encryption state of the files in the E:\Work Files\Armor Pictures directory. Notice the letter U to the left of the filenames, which tells you they are unencrypted. The second command you can see on the screen in Figure 25 is this: E:\Work Files\Armor Pictures>cipher /e /a.
Figure 25: Typing cipher /e /a encrypts the contents of the directory

46. cipher Command (continued)
Figure 27: Typing cipher /d /a dsc_4255.dng decrypts only that file
Figure 26: The cipher command confirms that the files were encrypted
To confirm the results of the cipher operation, enter the CIPHER command again, as shown in Figure 26. Note that the U to the left of each filename has been replaced with an E, indicating an encrypted file.
To decrypt a single file, simply add the filename of the file you want to decrypt after the command and the relevant switches. Figure 27 shows the CIPHER command being used to decipher dsc_4255.dng, a single file.

47. 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.

48. PowerShell (continued)
Figure shows two commands, dir and get-childitem, that do the same thing by default—show the contents of a directory.
Figure 28: Simple commands in PowerShell