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Book VII

Chapter 8

Windows

Commands

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Special Command Tricks

✦ Press the right-arrow key to recall the text of the last command that you

entered, one letter at a time. When you get to the spot where the new

command should differ from the previous command, start typing.

✦ Press F3 to recall all of the previous commands, from the current cursor

position to the end of the line.

✦ If you want to repeat a command that you’ve used recently, press

the up-arrow key. This recalls up to 50 of the most recently executed

commands. You can press Enter to execute a command as is, or you

can edit the command before you execute it.

Using the Control menu

Although the command window has no menu bar, it does have a menu that

you can access via the control box at the top-left corner of the window.

Besides the commands found on this menu for all windows (such as Move,

Size, and Minimize), this menu includes three additional commands:

✦ Edit: The Edit command leads to a submenu with several choices.

Several of these commands work together so that you can copy

information from the command window to the Clipboard and vice

versa. If you choose Edit➪Mark, you’re placed in a special editing mode

that lets you highlight text in the command window with the mouse.

(Normally, the mouse doesn’t do anything in the command window.)

You can then choose Edit➪Copy or just press Enter to copy the text that

you selected to the Clipboard.

You can also use the Edit menu to paste text from the Clipboard, to

scroll the window, and to search the window for text.

✦ Default: Lets you set default properties for the command window.

✦ Properties: Displays a Properties dialog box that you can use to change

the appearance of the window. You can change the font size, choose

background colors, and make other adjustments to make the command

window look good on your computer.

Special Command Tricks

Before I get into the details of using specific commands, I want to describe

some techniques you should familiarize yourself with. In many cases, these

techniques can let you accomplish in a single command what would

otherwise take dozens of separate commands.

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Special Command Tricks

Wildcards

Wildcards are one of the most compelling reasons to use the command

prompt. With wildcards, you can process all the files that match a particular

naming pattern with a single command. For example, suppose that you have

a folder containing 500 files, and you want to delete all the files that contain

the letters Y2K and end with the extension .doc, which happens to be 50

files. If you open a My Documents window, you’ll spend ten minutes picking

these files out from the list. From a command window, you can delete them

all with the single command Del *Y2K*.doc.

You can use two wildcard characters: An asterisk stands for any number

of characters, including zero, and an exclamation point stands for just one

character. Thus, !Text.doc would match files with names like aText.

doc, xText.doc, and 4Text.doc, but not abcText.doc or just Text.doc.

However, *Text.doc would match any of the names mentioned in the

previous sentence.

Wildcards work differently in Windows than they did in MS-DOS. In MS-DOS,

anything you typed after an asterisk was ignored. Thus, ab*cd.doc was the

same as ab*.doc. In Windows, the asterisk wildcard can come before static

text, so ab*cd.doc and ab*.doc are not the same.

Chaining commands

You can enter two or more commands on the same line by separating the

commands with an ampersand (&), like this:

C:\>copy *.doc a: & del *.doc

Here, the Copy command copies all the .doc files to the A: drive. Then, the

Del command deletes the .doc files.

Although that may be convenient, it’s also dangerous. What if the A: drive

fills up so that all the files can’t be copied? In that case, the Del command

executes anyway, deleting the files that didn’t get copied.

A safer alternative is to use two ampersands, which says to execute the

second command only if the first command finishes successfully. Thus:

C:\>copy *.doc a: && del *.doc

Now, the Del command will be executed only if the Copy command succeeds.

You can also use two pipe characters (the pipe is the vertical bar character

that’s above the backslash on the keyboard) to execute the second command

only if the first command fails. Thus,

C:\>copy *.doc a: || echo Oops!

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displays the message “Oops!” if the Copy command fails.

Finally, you can use parentheses to group commands. Then, you can use the

other symbols in combination. For example:

C:\>(copy *.doc a: && del *.doc) || echo Oops!

Here, the files are copied and then deleted if the copy was successful. If

either command fails, the message is displayed.

Redirection and piping

Redirection and piping are related techniques. Redirection lets you specify

an alternative destination for output that will be displayed by a command

or an alternative source for input that should be fed into a command. For

example, you can save the results of an ipconfig /all command to a file

named myconfig.txt like this:

C:\>ipconfig /all > myconfig.txt

Here, the greater-than sign (>) is used to redirect the command’s console

output.

If a command accepts input from the keyboard, you can use input redirection

to specify a file that contains the input you want to feed to the command.

For example, you can create a text file named lookup.txt with subcommands

for a command such as nslookup. Then, you can feed those scripted

subcommands to the nslookup command, like this:

C:\>nslookup < lookup.txt

Piping is a similar technique. It takes the console output from one command

and feeds it into the next command as input. Piping is often used with

special commands called filters, which are designed to read input from the

console, modify the data in some way, and then write it to the console.

For example, suppose that you want to display the contents of a file named

users.txt sorted into alphabetical order. You can use the Type command,

which displays a file on the console, and then you can pipe the output into

the Sort command, a filter that sorts its input and displays the sorted

output on the console. The resulting command would look like this:

C:\>type users.txt | sort

The vertical bar is often called the pipe character because it’s the symbol

used to indicate piping.

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Special Command Tricks

Environment variables

The command shell makes several environment variables available to

commands. Environment variables all begin and end with percent signs. You

can use an environment variable anywhere in a command. For example,

C:\>echo %OS% running on a %PROCESSOR_IDENTIFIER%

displays a line such as this:

Windows_NT running on an x86 Family 15 Model 2 Stepping 8,

GenuineIntel

Interestingly, Windows NT, Windows 2000 Server, Windows Server 2003, and

Windows Server 2008 all display “Windows_NT” for the operating system

name.

If the environment variable represents a path, you may need to enclose it in

quotation marks, like this:

C:\>dir “%HOMEPATH%”

This command displays the contents of the user’s home directory. The quo-

tation marks are required here because the environment variable expands to

a pathname that may include spaces, and the command shell requires that

long filenames that include spaces must be enclosed in quotation marks.

Table 8-1 lists the environment variables that are available to you and your

commands.

Table 8-1 Environment Variables

Variable Description

%ALLUSERSPROFILE%

The location of the All Users profile

%APPDATA%

The path where applications store data

by default

%CD%

The path to the current directory

%CMDCMDLINE%

The command line that was used to start

the command shell

%CMDEXTVERSION%

The version number of the command shell

%COMPUTERNAME%

The computer’s name

%COMSPEC%

The path to the command shell executable

(cmd.exe)

%DATE%

The current date in the format generated

by the date /t command

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Variable Description

%ERRORLEVEL%

The error returned by the most recent

command

%HOMEDRIVE%

The drive letter of the user’s home directory

%HOMEPATH%

The path to the user’s home directory

%HOMESHARE%

The network path to the user’s shared

home directory

%LOGONSERVER%

The name of the domain controller the

user logged on to

%NUMBER_OF_PROCESSORS%

The number of processors on the computer

%OS%

The name of the operating system

%PATH%

The current search path

“%PATHEXT%”

A list of the extensions the operating

system treats as executable files

%PROCESSOR_ARCHITECTURE%

The chip architecture of the processor

%PROCESSOR_IDENTIFIER%

A description of the processor

%PROCESSOR_REVISION%

The revision level of the processor

%PROMPT%

The current prompt string

%RANDOM%

A random number between 1 and 32,767

%SYSTEMDRIVE%

The drive containing the operating system

%SYSTEMROOT%

The path to the operating system

%TEMP%

The path to a temporary folder for

temporary files

%TMP% Same as %TEMP%

%TIME%

The time in the format produced by the

time /t command

%USERDOMAIN%

The name of the user’s domain

%USERNAME%

The user’s account name

%USERPROFILE%

The path to the user’s profile

%WINDIR%

The path to the operating system directory

Batch files

A batch file is simply a text file that contains one or more commands. Batch

files are given the extension .bat and can be run from a command prompt

as if they were commands or programs. You can also run a batch file from

the Start menu by choosing Start➪Run, typing the name of the batch file,

and clicking OK.

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The EventCreate Command

As a network administrator, you’ll find plenty of uses for batch files. Most of

them won’t be very complicated. For example, here are some examples of

very simple batch files I’ve used:

✦ I once used a one-line file to copy the entire contents of an important

shared network drive to a user’s computer every night at 10 p.m. The

user had just purchased a new Dell computer with a 100GB drive, and

the server had only a 20GB drive. The user wanted a quick-and-dirty

backup solution that would complement the regular tape backups that

ran every night.

✦ I’ve also used a pair of short batch files to stop and then restart

Exchange server before and after nightly backups for backup software

that didn’t have an Exchange plug-in that could back up the mail store

while it was open.

✦ If I frequently need to work with several related folders at once, I create

a short batch file that opens Explorer windows for each of the folders.

(You can open an Explorer window from a batch file simply by typing

the path to the folder that you want to open as a command.) Then, I

place the batch file on my desktop so I can get to it quickly.

You can also use batch files to create logon scripts that are executed

whenever a user logs on. Microsoft keeps trying to get users to use profiles

instead of logon scripts, but many networks still use logon scripts.

The EventCreate Command

The EventCreate command lets you create an event that’s added to one

of the Windows event logs. This can be useful if you want to make a note of

something unusual that’s happened. It’s often used in batch files to mark the

start or completion of a task such as a nightly backup.

Here’s the basic syntax:

eventcreate [options]

eventcreate /T type /D “description” /ID eventide

[/L logname] [/SO sourcename]

[/S system [/U username [/P password]]]

Here’s a description of the options:

✦ /T: Specifies the type. The options are Information, Warning, or

Error.

✦ /D: Provides a descriptive message that’s saved in the log. Use quotes if

the message contains more than one word.

✦ /ID: A number from 1 to 1000.

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✦ /L: The name of the log to write the event to. The default is

Application.

✦ /SO: A string that represents the source of the event. The default is

EventCreate. If you specify this option, you must also specify the /L

option.

✦ /S: The name of the system on which the event should be recorded.

✦ /U: The user account to use when logging the event. You can specify

this option only if you also specify /S.

✦ /P: The password. You can specify this option only if you also specify /U.

Here’s an example that writes an informational message to the Application log:

eventcreate /t information /id 100 /d “Nightly processing

completed” /L Application /SO Nightly

Figure 8-2 shows an event created by the above command.

Figure 8-2:

An event

generated

by the

EventCreate

command.

Net Commands

Among the more useful commands for network administrators are the Net

Services commands. These commands are all two-word commands,

beginning with Net — such as Net Use and Net Start. In the following

sections, I present each of the Net commands, in alphabetical order for

handy reference. First, though, I want to point out a few details about the

Net commands:

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Net Commands

✦ You can get a quick list of the available Net commands by typing net /?

at a command prompt.

✦ You can get brief help for any Net command by typing net help

command. For example, to display help for the Net Use command,

type net help use. (Yes, we all could use some help.)

✦ Many of the Net commands prompt you for confirmation before

completing an operation. For these commands, you can specify /Y or /N

to bypass the confirmation prompt. You’ll want to do that if you include

these commands in a batch file that runs unattended. Note that you can

use /Y or /N on any Net command, even if it doesn’t prompt you for

confirmation. So I suggest that you place /Y on every Net command in a

batch file that you intend on running unattended.

The Net Accounts command

This command updates user account policies for password requirements.

Here’s the command syntax:

net accounts [/forcelogoff:{minutes | no}]

[/minpwlen:length] [/maxpwage:{days | unlimited}]

[/minpwage:days] [/uniquepw:number]

[/domain]

The following paragraphs describe the parameters for the Net Accounts

command:

✦ Forcelogoff: Specifies how long to wait before forcing a user off the

system when the user’s logon time expires. The default value, no,

prevents users from being forced to log off. If you specify a number, the

user will be warned a few minutes before being forcibly logged off.

✦ Minpwlen: Specifies the minimum length for the user’s password.

Length can be from 0 through 127. The default is 6.

✦ Maxpwage: Specifies the number of days a user’s password is considered

valid. Unlimited means the password will never expire. Days can be

from 1 through 49,710, which is about 135 years. The default is 90.

✦ Minpwage: Specifies the minimum number of days after a user changes

a password before the user can change it again. The default value is 0.

You should usually set this value to 1 day in order to prevent users from

bypassing the Uniquepw policy.

✦ Uniquepw: Indicates how many different passwords the user must

use before he or she is allowed to reuse the same password again. The

default setting is 5. The range is from 0 to 24.

✦ Domain: Specifies that the operation should be performed on the

primary domain controller rather than on the local computer.

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If you enter Net Accounts without any parameters, the command simply

displays the current policy settings.

Here’s an example that sets the minimum and maximum password ages:

C:\>net accounts /minpwage:7 /maxpwage:30

The Net Computer command

This command creates or deletes a computer account. Here’s the syntax:

net computer \\computername {/add | /del}

The following paragraphs describe the parameters for the Net Computer

command:

✦ Computername: The name of the computer to add or delete.

✦ Add: Creates a computer account for the specified computer.

✦ Del: Deletes the specified computer account.

Here’s an example that adds a computer named Theodore:

C:\>net computer \\theodore /add

The Net Config command

This command lets you view or configure various network services. Here’s

the syntax:

net config [{server|workstation}]

To configure server settings, use this syntax:

net config server [/autodisconnect:time]

[/srvcomment:”text”] [/hidden:{yes | no}]

The following paragraphs describe the parameters for the Net Config

command:

✦ Server: Lets you display and configure the Server service while it’s

running.

✦ Workstation: Lets you display and configure the Workstation service

while it’s running.

✦ Autodisconnect: Specifies how long a user’s session can be inactive

before it’s disconnected. Specify –1 to never disconnect. The range is –1

to 65535 minutes, which is about 45 days. The default is 15 minutes.

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✦ Srvcomment: Specifies a description of the server. The comment can be

up to 48 characters long and should be enclosed in quotation marks.

✦ Hidden: Specifies whether the server appears in screens that display

available servers. Hiding a server doesn’t make the server unavailable;

it just means that the user will have to know the name of the server in

order to access it. The default is No.

Here’s an example that sets a server’s descriptive comment:

C:\>net config server /srvcomment:”DHCP Server”

The Net Continue command

This command continues a service you’ve suspended with the Net Pause

command. Here’s the syntax:

net continue service

Here are some typical services that you can pause and continue.

✦ Netlogon: The Net Logon service.

✦ Schedule: The Task Scheduler service.

✦ Server: The Server service.

✦ Workstation: The Workstation service.

Here’s an example that continues the Workstation service:

C:>net continue workstation

If the service name has embedded spaces, enclose the service name in

quotation marks. For example, this command continues the NT LM Security

Support Provider service:

C:\>net continue “nt lm security support provider”

The Net File command

This command lists all open shared files and the number of file locks placed

on each file. You can also use this command to close files and remove locks,

which is a useful procedure when a user manages to accidentally leave a file

open or locked. Here’s the syntax:

C:\>net file [id [/close]]

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