The Cmdlets
There are several buildin CmdLets for working with the containing host.
Out-Host - Send the output to the command line.
Out-Host [-InputObject ] [-Paging] []
Get-Host - Gets an object that represents the current host program and displays PowerShell version and regional information.
Get-Host []
Read-Host - Reads a line of input from the console
Read-Host
[-Caption ]
[-DefaultOption ]
[-ErrorMessage ]
[-Gui]
[-HelpTexts ]
[-Options ]
[-Prompt] [-Title ]
[-ValidatePattern ]
[]Read-Host
[-AsSecureString]
[-ErrorMessage ]
[-Gui]
[-Title ]
[-ValidatePattern ]
[]
Write-Host - Writes customized output to a host.
Write-Host
[-BackgroundColor
{Black|DarkBlue|DarkGreen|DarkCyan|DarkRed|DarkMagenta|DarkYellow|Gray|DarkGray|Blue|Green|Cyan|Red|Magenta|Yellow|White}]
[-ForegroundColor
{Black|DarkBlue|DarkGreen|DarkCyan|DarkRed|DarkMagenta|DarkYellow|Gray|DarkGray|Blue|Green|Cyan|Red|Magenta|Yellow|White}]
[-NoNewline]
[-Separator ]
[[-Object] ]
[]
These read and write Cmdlets are just wrappers around the built-in host object retrieved with the $host variable or the Get-Host Cmdlet.
PS C:\> (Get-Host)
Name : ConsoleHost
Version : 2.0
InstanceId : ac35cdb0-36c9-45a9-b692-a9443e35bd70
UI : System.Management.Automation.Internal.Host.InternalHostUserInterface
CurrentCulture : en-US
CurrentUICulture : en-US
PrivateData : Microsoft.PowerShell.ConsoleHost+ConsoleColorProxy
IsRunspacePushed : False
Runspace : System.Management.Automation.Runspaces.LocalRunspace
The interesting object here is the UI member of type InternalHostUserInterface most likely derived from the PSHostUserInterface interface. A call to Get-Member on that object will display the supported commands:
PS C:\> (Get-Host).UI | Get-Member
TypeName: System.Management.Automation.Internal.Host.InternalHostUserInterface
Name MemberType Definition
---- ---------- ----------
Equals Method System.Boolean Equals(Object obj)
GetHashCode Method System.Int32 GetHashCode()
GetType Method System.Type GetType()
Prompt Method System.Collections.Generic.Dictionary`2[[System.String, mscorlib, Version=2.0.0.0,...
PromptForChoice Method System.Int32 PromptForChoice(String caption, String message, Collection`1 choices,...
PromptForCredential Method System.Management.Automation.PSCredential PromptForCredential(String caption, Stri...
ReadLine Method System.String ReadLine()
ReadLineAsSecureString Method System.Security.SecureString ReadLineAsSecureString()
ToString Method System.String ToString()
Write Method System.Void Write(String value), System.Void Write(ConsoleColor foregroundColor, C...
WriteDebugLine Method System.Void WriteDebugLine(String message)
WriteErrorLine Method System.Void WriteErrorLine(String value)
WriteLine Method System.Void WriteLine(), System.Void WriteLine(String value), System.Void WriteLin...
WriteProgress Method System.Void WriteProgress(Int64 sourceId, ProgressRecord record)
WriteVerboseLine Method System.Void WriteVerboseLine(String message)
WriteWarningLine Method System.Void WriteWarningLine(String message)
RawUI Property System.Management.Automation.Host.PSHostRawUserInterface RawUI {get;}
You'll see some obvious relationships here to the other Cmdlets dealing with I/O such as Write-Progress, Write-Debug, Write-Warning, Write-Error and so forth.
Securing Your Output
I hinted on Yellow above in that you can control the foreground and background color of console output. Here's a practical application of using color. Consider the case where you are running a long-lived process that prints sensitive information to the console and you don't want to have others peek over your shoulder and read it. This is a perfect example of using the output color schemes. In this case, you can make the foreground and background color the same and it will look just like a color block. When you want to retrieve the output text, you can always cut and paste it from the console, but you won't be able to read it directly!
