Special variables have a predefined meaning within a computer programming language.



Task

List the special variables used within the language.




Grid[Partition[Names["$*"],4]]
->
$Aborted                       $ActivationGroupID             $ActivationKey                 $ActivationUserRegistered     
$AddOnsDirectory               $AllowDataUpdates              $AllowDocumentationUpdates     $AllowInternet                
$AssertFunction                $Assumptions                   $BaseDirectory                 $BatchInput                   
$BatchOutput                   $BoxForms                      $ByteOrdering                  $Canceled                     
$CharacterEncoding             $CharacterEncodings            $CommandLine                   $CompilationTarget            
$ConditionHold                 $ConfiguredKernels             $Context                       $ContextPath                  
$ControlActiveSetting          $CreationDate                  $CurrentLink                   $DateStringFormat             
$DefaultFont                   $DefaultFrontEnd               $DefaultImagingDevice          $DefaultPath                  
$Display                       $DisplayFunction               $DistributedContexts           $DynamicEvaluation            
$Echo                          $Epilog                        $ExportFormats                 $Failed                       
$FinancialDataSource           $FormatType                    $FrontEnd                      $FrontEndSession              
$GeoLocation                   $HistoryLength                 $HomeDirectory                 $IgnoreEOF                    
$ImagingDevices                $ImportFormats                 $InitialDirectory              $Input                        
$InputFileName                 $Inspector                     $InstallationDate              $InstallationDirectory        
$InstalledServices             $InterfaceEnvironment          $InternetProxyRules            $IterationLimit               
$KernelCount                   $KernelID                      $Language                      $LaunchDirectory              
$LibraryPath                   $LicenseExpirationDate         $LicenseID                     $LicenseProcesses             
$LicenseServer                 $LicenseSubprocesses           $LicenseType                   $Line                         
$Linked                        $LinkSupported                 $LoadedFiles                   $MachineAddresses             
$MachineDomain                 $MachineDomains                $MachineEpsilon                $MachineID                    
$MachineName                   $MachinePrecision              $MachineType                   $MaxExtraPrecision            
$MaxLicenseProcesses           $MaxLicenseSubprocesses        $MaxMachineNumber              $MaxNumber                    
$MaxPiecewiseCases             $MaxPrecision                  $MaxRootDegree                 $MessageGroups                
$MessageList                   $MessagePrePrint               $Messages                      $MinMachineNumber             
$MinNumber                     $MinorReleaseNumber            $MinPrecision                  $ModuleNumber                 
$NetworkLicense                $NewMessage                    $NewSymbol                     $Notebooks                    
$NumberMarks                   $Off                           $OperatingSystem               $Output                       
$OutputForms                   $OutputSizeLimit               $Packages                      $PacletSite                   
$ParentLink                    $ParentProcessID               $PasswordFile                  $PatchLevelID                 
$Path                          $PathnameSeparator             $PerformanceGoal               $PipeSupported                
$Post                          $Pre                           $PreferencesDirectory          $PrePrint                     
$PreRead                       $PrintForms                    $PrintLiteral                  $PrintServiceRequest          
$PrintServiceResponse          $PrintShortErrorMessages       $PrintWSDLDebug                $ProcessID                    
$ProcessorCount                $ProcessorType                 $ProductInformation            $ProgramName                  
$RandomState                   $RecursionLimit                $ReleaseNumber                 $RootDirectory                
$ScheduledTask                 $ScriptCommandLine             $SessionID                     $SetParentLink                
$SharedFunctions               $SharedVariables               $SoundDisplay                  $SoundDisplayFunction         
$SuppressInputFormHeads        $SynchronousEvaluation         $SyntaxHandler                 $System                       
$SystemCharacterEncoding       $SystemID                      $SystemWordLength              $TemporaryDirectory           
$TemporaryPrefix               $TextStyle                     $TimedOut                      $TimeUnit                     
$TimeZone                      $TopDirectory                  $TraceOff                      $TraceOn                      
$TracePattern                  $TracePostAction               $TracePreAction                $Urgent                       
$UserAddOnsDirectory           $UserBaseDirectory             $UserBasePacletsDirectory      $UserDocumentsDirectory