Avoid disasters in PowerShell

WhatIf

If you are unsure about the operation or action that is going to happen after executing a PowerShell cmdlet, use "WhatIf". This will tell you what it will do without actually doing it. So that you will have an understanding of what the cmdlet is going to perform. Consider the below PS statement. 

Get-Service | where {$PSItem.name -eq "bits"} | Start-Service

Lets assume that you are unsure of what the above statement will do. Add -WhatIf at the end and execute it.

Get-Service | where {$PSItem.name -eq "bits"} | Start-Service -WhatIf

Example: WhatIf

The above screenshot explains the operation that will perform if you execute the statement. In this case it will start the BITS service. 

Confirm

Lets consider another scenario where you want to confirm the action from the user before actually executing it straight away. You can use "Confirm" in this case. See the below example. 

Clear-EventLog -LogName System -Confirm

Example: Confirm