Error Handling Powershell 2.0
being able to handle errors helps to ensure that an unexpected event will not go on to wreck the system you are working on. Take the example below. Every week in our sample company (MyCompany.Com) Human Resources are going to upload a list telling us who should have access to the Expenses database. If a name isn’t in the list from HR we’re going to remove it from the group and that user will no longer be able to log expense claims: $AuthorizedUsers= Get-Content \\ FileServer\HRShare\UserList.txt $CurrentUsers=Get-ADGroupMember "Expenses Claimants" Foreach($User in $CurrentUsers) { If($AuthorizedUsers -notcontains $User) { Remove-ADGroupMember -Identity "Expenses Claimants" -User $User } } Now, you can see where this is going to go wrong. One week HR doesn’t get around to uploading the list or, just as we are about to access the list, the file server dies. Suddenly PowerShell throws an error on the Get-Content cmdlet and the $AuthorizedUser variable remains empty. Because our script doesn’t handle errors, it continues to run and, in a very short space of time, it has removed every user from our expenses group. Pretty soon the irate phone calls start flooding in and life gets a little less happy. The way to avoid all this is to catch the errors and then handle the event that caused them (which in this case is halt the script and have a shout at someone in HR). Terminating and Non-Terminating Errors One of the key things to know when catching errors is that only certain errors can be caught by default. Errors come in two types – terminating and non-terminating. A terminating error is an error that will halt a function or operation. If you make a syntax error or run out of memory, that is a terminating error. Terminating errors can be caught and handled. Non-terminating errors allow Powershell to continue and usually come from cmdlets or other managed situations. Under normal circumstances they cannot be caught by Try-Catch-Finally. The Get-Content error in the example above is a non-terminating error. Treating Non-Terminating Errors as Terminating So how do you catch a Non-Terminating error? Basically, you tell PowerShell to treat it as terminating. To do this you use the ErrorAction parameter. Every PowerShell cmdlet supports ErrorAction. By specifying -ErrorAction Stop on the end of a cmdlet you ensure that any errors it throws are treated as terminating and can be caught. In our example above we are going to change our Get-Content line to: $AuthorizedUsers= Get-Content \\ FileServer\HRShare\UserList.txt -ErrorAction Stop Treating All Errors as Terminating It is also possible to tr
Keith BabinecJune 9, 201320 0 0 0 Today’s post (and this blog's inaugural post!) is An Introduction to Error Handling in PowerShell. We will discuss error types, the $error variable, error action preferences, try/catch blocks, and $lastexitcode. The first requirement is to understand the types of errors that can occur during execution. Terminating vs. Non-Terminating Errors: Terminating Error: A serious error during execution that halts the command (or script execution) completely. Examples can include non-existent cmdlets, syntax errors http://www.vexasoft.com/blogs/powershell/7255220-powershell-tutorial-try-catch-finally-and-error-handling-in-powershell that would prevent a cmdlet from running, or other fatal errors. Non-Terminating Error: A non-serious error that allows execution to continue despite the failure. Examples include operational errors such file not found, permissions problems, etc. Update 12/13/2013: Writing a cmdlet? For further information regarding how a cmdlet should determine when to throw a terminating error or non-terminating https://blogs.msdn.microsoft.com/kebab/2013/06/09/an-introduction-to-error-handling-in-powershell/ error, MSDN has a niceexplanationhere. Update 12/13/2013: Want to know if an error you encountered is terminating or non-terminating? Check to see ifthe error behavioris affected by changing the$ErrorActionPreference. According to the MSDN documentation here, "Neither $ErrorActionPreference nor the ErrorAction common parameter affect how Windows PowerShell responds to terminating errors (those that stop cmdlet processing).". The $error variable: When either type of error occurs during execution, it is logged to a global variable called $error. This variable is a collection of PowerShell Error Objects with the most recent error at index 0. On a freshly initialized PowerShell instance (no errors have occurred yet) the $error variable is ready and waiting as an empty collection: PS C:\> $error.GetType() IsPublic IsSerial NameBaseType ----- ----- -------- TrueTrueArrayListSystem.Object PS C:\> $error.Count 0 In the next snippet I have executed a cmdlet that doesn’t exist, throwing an error. If we grab the count on $error, you will notice it has increased to one item. Dumping that object to the pipeli
Platforms Ask the Core Team Cloud Platform https://blogs.technet.microsoft.com/heyscriptingguy/2014/07/09/handling-errors-the-powershell-way/ Blogs Hybrid Cloud Microsoft Azure Building Clouds Datacenter Management Hybrid http://stackoverflow.com/questions/4691874/powershell-2-0-and-how-to-handle-exceptions Cloud Operations Management Suite (OMS) System Center Virtual Machine Manager System Center Service Manager System Center Operations Manager System Center Orchestrator System Center Data Protection Manager Client Management System Center Configuration Manager Configuration Manager Team System Center error handling Service Manager Malware Protection Center Microsoft Intune Server Update Services Enterprise Mobility Virtualization, VDI & Remote Desktop Virtualization Team Ben Armstrong's Virtualization Remote Desktop Services Ask the Core Team on Hyper-V Enterprise Mobility File & Storage & High Availability File & Storage Ask the Core Team error handling powershell on Failover Cluster Clustering & High Availability Windows Server Management PowerShell Hey Scripting Guy (PowerShell) Networking Identity, Access & Security Datacenter and Private Cloud Security Active Directory Enterprise Mobility Ask Directory Services Hey, Scripting Guy! Blog Learn about Windows PowerShell Handling Errors the PowerShell Way ★★★★★★★★★★★★★★★ July 9, 2014July 4, 2015 by The Scripting Guys // 3 Comments 0 0 0 Summary: Trevor Sullivan talks about handling errors in Windows PowerShell. Microsoft Scripting Guy, Ed Wilson, is here. Today we have guest blogger and Windows PowerShell MVP, Trevor Sullivan… also find Trevor on Twitter (https://twitter.com/pcgeek86) and his blog (http://trevorsullivan.net) Microsoft Scripting Guy, Ed Wilson, just wrote a post about how to use the Try-Catch-Finally blocks in Windows PowerShell. But have you ever wondered if that was the only way to handle errors? It turns out that although it’
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up PowerShell 2.0 and how to handle exceptions? up vote 7 down vote favorite 5 Why I get error message printed on the console when running these two simple samples ? I want that I get "Error testing :)" printed on the console insted of: Get-WmiObject : The RPC server is unavailable. (Exception from HRESULT: 0x800706BA) At line:3 char:15 + Get-WmiObject <<<< -ComputerName possibly.nonexisting.domain.com -Credential (Get-Credential) -Class Win32_logicaldisk + CategoryInfo : InvalidOperation: (:) [Get-WmiObject], COMException + FullyQualifiedErrorId : GetWMICOMException,Microsoft.PowerShell.Commands.GetWmiObjectCommand or Attempted to divide by zero. At line:3 char:13 + $i = 1/ <<<< 0 + CategoryInfo : NotSpecified: (:) [], ParentContainsErrorRecordException + FullyQualifiedErrorId : RuntimeException First example: try { $i = 1/0 Write-Host $i } catch [Exception] { Write-Host "Error testing :)" } Second example: try { Get-WmiObject -ComputerName possibly.nonexisting.domain.com -Credential (Get-Credential) -Class Win32_logicaldisk } catch [Exception] { Write-Host "Error testing :)" } Thank you very much! powershell exception-handling powershell-v2.0 share|improve this question asked Jan 14 '11 at 14:06 Primoz 88083862 add a comment| 1 Answer 1 active oldest votes up vote 11 down vote accepted First example The error happens at compile/parsing time (PowerShell is clever enough), so that the code is not even executed and it cannot catch anything, indeed. Try this code instead and you will catch an exception: try { $x = 0 $i = 1/$x Write-Host $i } catch [Exception] { Write-Host "Error testing :)" } Second example If you set $ErrorActionPreference = 'Stop' globally then you will get "Error testing :)" printed, as expected. But your $ErrorActionPreference is presumably 'Continue': in that case there is no terminating error/exception and you just get the non terminating error message printed to the host by the engine. Instead of the global $ErrorActio