This chapter is from the book
This chapter is from the book
This chapter is from the book
Understanding Errors
PowerShell errors are divided into two types: terminating and nonterminating. Terminating errors, as the name implies, stop a command. Nonterminating errors are generally just reported without stopping a command. Both types of errors are reported in the $Error variable, which is a collection of errors that have occurred during the current PowerShell session. This collection contains the most recent error, as indicated by $Error[0] up to $MaximumErrorCount, which defaults to 256.
Errors in the $Error variable can be represented by the ErrorRecord object. It contains error exception information as well as a number of other properties that are useful for understanding why an error occurred
The next example shows the information that is contained in InvocationInfo property of an ErrorRecord object:
PS C:\> $Error[0].InvocationInfo
MyCommand : Get-ChildItem
ScriptLineNumber : 1
OffsetInLine : -2147483648
ScriptName :
Line : dir z:
PositionMessage :
At line:1 char:4
+ dir <<<< z:
InvocationName : dir
PipelineLength : 1
PipelinePosition : 1
PS C:\>
|
Based on this information, you can determine a number of details about $Error[0], including the command that caused the error to be thrown. This information is crucial to understanding errors and handling them effectively.
Use the following command to see a full list of ErrorRecord properties:
PS C:\> $Error[0] | get-member -MemberType Property
TypeName: System.Management.Automation.ErrorRecord
Name MemberType Definition
---- ---------- ----------
CategoryInfo Property System.Management.Automation.ErrorCategoryI...
ErrorDetails Property System.Management.Automation.ErrorDetails E...
Exception Property System.Exception Exception {get;}
FullyQualifiedErrorId Property System.String FullyQualifiedErrorId {get;}
InvocationInfo Property System.Management.Automation.InvocationInfo...
TargetObject Property System.Object TargetObject {get;}
PS C:\>
|
Table 3.1 shows the definitions for each of the ErrorRecord properties that are listed in the preceding example:
Table 3.1. ErrorRecord Property Definitions
|
Property |
Definition |
| CategoryInfo |
Indicates under which category an error is classified |
| ErrorDetails |
Can be null, but when used provides additional information about the error |
| Exception |
The error that occurred |
| FullyQualifiedErrorId |
Identifies an error condition more specifically |
| InvocationInfo |
Can be null, but when used explains the context in which the error occurred |
| TargetObject |
Can be null, but when used indicates the object being operated on |