$$`

Contains the last token of the last line received by the shell.

$?

Contains True if last operation succeeded and False otherwise.

$^

Contains the first token of the last line received by the shell.

$_

Contains the current pipeline object, used in script blocks, filters, and the where statement.

$Args

Contains an array of the parameters passed to a function.

$DebugPreference

Specifies the action to take when data is written using Write-Debug in a script or WriteDebug in a cmdlet or provider.

$Error

Contains objects for which an error occurred while being processed in a cmdlet.

$ErrorActionPreference

Specifies the action to take when data is written using Write-Error in a script or WriteError in a cmdlet or provider.

$foreach

Refers to the enumerator in a foreach loop.

$Home

Specifies the user's home directory. Equivalent of %homedrive%%homepath%.

$Input

Use in script blocks that are in the middle of a pipeline.

$LASTEXITCODE

Contains the exit code of the last Win32 executable execution.

$MaximumAliasCount

Contains the maximum number of aliases available to the session.

$MaximumDriveCount

Contains the maximum number of drives available, excluding those provided by the underlying operating system.

$MaximumFunctionCount

Contains the maximum number of functions available to the session.

$MaximumHistoryCount

Specifies the maximum number of entries saved in the command history.

$MaximumVariableCount

Contains the maximum number of variables available to the session.

$PsHome

The directory where the Windows PowerShell is installed.

$Host

Contains information about the current host.

$OFS

Output Field Separator, used when converting an array to a string. By default, this is set to the space character. The following example illustrates the default setting and setting OFS to a different value:

$ReportErrorShowExceptionClass

When set to TRUE, shows the class names of displayed exceptions.

$ReportErrorShowInnerException

When set to TRUE, shows the chain of inner exceptions. The display of each exception is governed by the same options as the root Exception, that is, the options dictated by $ReportErrorShow* will be used to display each exception.

$ReportErrorShowSource

When set to TRUE, shows the assembly names of displayed exceptions.

$ReportErrorShowStackTrace

When set to TRUE, emits the stack traces of exceptions.

$ShouldProcessPreference

Specifies the action to take when ShouldProcess is used in a cmdlet.

$ShouldProcessReturnPreference

Value returned by ShouldPolicy

$StackTrace

Contains detailed stack trace information about the last error.

$VerbosePreference

Specifies the action to take when data is written using Write-Verbose in a script or WriteVerbose in a cmdlet or provider.

$WarningPreference

Specifies the action to take when data is written using Write-Warning in a script or WriteWarning in a cmdlet or provider.