问题
I am trying to handle setting a PowerShell variable from a registry key.
So I use a try{} catch {} to get rid of eventual errors in case the key doesn't exists. However, I still get the error output on console.
$ZZ_ConVTL = try { (Get-ItemProperty -path "HKCU:\Console" -name VirtualTerminalLevel).VirtualTerminalLevel } catch { "N/A" }
...
# Output:
Get-ItemProperty : Property VirtualTerminalLevel does not exist at path HKEY_CURRENT_USER\Console.
At C:\Users\Administrator\Documents\xxxx\xxxx.ps1:181 char:32
+ ... = try { (Get-ItemProperty -path "HKCU:\Console" -name VirtualTermi ...
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidArgument: (VirtualTerminalLevel:String) [Get-ItemProperty], PSArgumentException
+ FullyQualifiedErrorId : System.Management.Automation.PSArgumentException,Microsoft.PowerShell.Commands.GetItemPropertyCommand
How can I handle and avoid this error from showing up in the console?
回答1:
What your Get-ItemProperty call emits is a non-terminating error, whereas try / catch only catches terminating errors.
- Non-terminating errors are far more common that terminating ones.
Use common parameter -ErrorAction Stop to promote (the first) non-terminating error generated by a cmdlet to a terminating one that try / catch handles.
You can generally achieve the same effect by setting preference variable$ErrorActionPreference = 'Stop' beforehand, but note that doing so has no effect on calls to external programs and on functions implemented in modules.
See also:
The about_Try_Catch_Finally help topic.
A description of the fundamental error types in the context of guidance for command authors on when to emit a terminating vs. a non-terminating error: this answer.
A comprehensive overview of PowerShell's surprisingly complex error handling: this GitHub docs issue.
来源：https://stackoverflow.com/questions/59627391/how-to-handle-failed-variable-assignments-in-powershell