Datasheet

UNDERSTAND THE BASICS OF POWERSHELL 25
Administering Service Delivery
PART I
FIGURE 1.10 Listing the currently used variables
In addition to variables that you de ne yourself, there are special variables called
shell variables built into PowerShell. Shell variables are automatically created
by PowerShell. An example of a shell variable is $null , which always means
that something has no value. For example, if you had an Active Directory user
object and you wanted to clear the Description attribute, you could set the
Description property to $null .  is can be accomplished with the following
command:
Set-ADUser “Lincoln Alexander” -Description $null
 ere are many other shell variables in PowerShell. Table 1.5 lists some of the more
common shell variables you’ll encounter.
TABLE 1.5 Common Shell Variables
Variable Description
$_ Refers to the current object that is being processed in a pipeline or a loop.
$Error When an error is encountered in the command, the error is stored here.
$Home The home directory of the current user.
$true Represents the condition True .
$false Represents the condition False .
$null Represents a null entry, meaning the property is blank.
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