$A = Get-ChildItem C:\temp
try {
$B = Get-ChildItem2 C:\temp
} catch {
$Error[0] | Out-File -filepath c:\temp\test.log
}
I have forced an error to occur on line 3 by including an invalid command. When run interactively no output is produced on the screen, which is fine because when run as a scheduled task, no one will be there to see it anyways. The log file contains the following content:
Get-ChildItem2 : The term 'Get-ChildItem2' is not recognized as the name of a cmdlet, function, script file, orThe output log contains the normal error detail you'd see if running the command interactively.
operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try
again.
At C:\Temp\test.ps1:3 char:7
+ $B = Get-ChildItem2 C:\temp
+ ~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Get-ChildItem2:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException
Let's enhance the log with something normal like a timestamp.
(get-date -UFormat "%Y%m%d%H%M%S") + ": " + $Error[0] | Out-File -filepath c:\temp\test.log
The output log now contains the content:
20151209123349: The term 'Get-ChildItem2' is not recognized as the name of a cmdlet, function, script file, or operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try again.We successfully added the timestamp, but lost many details such as the line that incurred the error. Let's see if we can restore the missing data to the log file. When we look at the error object, we can see the following information:
PS C:\Temp> $Error[0] | gm
TypeName: System.Management.Automation.ErrorRecord
Name MemberType Definition
---- ---------- ----------
Equals Method bool Equals(System.Object obj)
GetHashCode Method int GetHashCode()
GetObjectData Method void GetObjectData(System.Runtime.Serialization.SerializationInfo info, System....
GetType Method type GetType()
ToString Method string ToString()
CategoryInfo Property System.Management.Automation.ErrorCategoryInfo CategoryInfo {get;}
ErrorDetails Property System.Management.Automation.ErrorDetails ErrorDetails {get;set;}
Exception Property System.Exception Exception {get;}
FullyQualifiedErrorId Property string FullyQualifiedErrorId {get;}
InvocationInfo Property System.Management.Automation.InvocationInfo InvocationInfo {get;}
PipelineIterationInfo Property System.Collections.ObjectModel.ReadOnlyCollection[int] PipelineIterationInfo {g...
ScriptStackTrace Property string ScriptStackTrace {get;}
TargetObject Property System.Object TargetObject {get;}
PSMessageDetails ScriptProperty System.Object PSMessageDetails {get=& { Set-StrictMode -Version 1; $this.Except...
We have a default to ToString() method. Let's see what that gets us:
PS C:\Temp> $Error[0].ToString()
The term 'Get-ChildItem2' is not recognized as the name of a cmdlet, function, script file, or operable program. Check
the spelling of the name, or if a path was included, verify that the path is correct and try again.
That matches the text that ended up in the second log file. Let's see if we can find where the missing data lives in the ErrorRecord object. The initial output contains the keywords CategoryInfo and FullyQualifiedErrorId. Those are both properties, so let's look at those:
PS C:\Temp> $Error[0].CategoryInfo
Category : ObjectNotFound
Activity :
Reason : CommandNotFoundException
TargetName : Get-ChildItem2
TargetType : String
PS C:\Temp> $Error[0].FullyQualifiedErrorId
CommandNotFoundException
That's a start as that data is included in the initial output, but is unformatted. We're still missing the pointer to the faulting line in the script. Looking through the other properties, we see that the InvocationInfo property contains the data we were looking for in the PositionMessage property.
PS C:\Temp> $Error[0].InvocationInfo
MyCommand :
BoundParameters : {}
UnboundArguments : {}
ScriptLineNumber : 3
OffsetInLine : 7
HistoryId : 36
ScriptName : C:\Temp\test.ps1
Line : $B = Get-ChildItem2 C:\temp
PositionMessage : At C:\Temp\test.ps1:3 char:7
+ $B = Get-ChildItem2 C:\temp
+ ~~~~~~~~~~~~~~
PSScriptRoot : C:\Temp
PSCommandPath : C:\Temp\test.ps1
InvocationName : Get-ChildItem2
PipelineLength : 0
PipelinePosition : 0
ExpectingInput : False
CommandOrigin : Internal
DisplayScriptPosition :
At this point, we could come up with a mildly complex function to recreate the initial output by referencing the appropriate properties. However, there's an easier way to get the error output.
Out-String
In all my years of PowerShell-ing, I've never had a reason to use Out-String, as most items will normally render as a string to the console or a file (as was evidenced above). Out-String does exactly what we want in this instance.
PS C:\Temp> $Error[0] | Out-String
Get-ChildItem2 : The term 'Get-ChildItem2' is not recognized as the name of a cmdlet, function, script file, or
operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try
again.
At C:\Temp\test.ps1:3 char:7
+ $B = Get-ChildItem2 C:\temp
+ ~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Get-ChildItem2:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException
From the console, this output is unsurprisingly identical to the statement $Error[0] issued all by itself.
We can add this into our script as follows:
(get-date -UFormat "%Y%m%d%H%M%S") + ": " + ($Error[0] | Out-String) | Out-File -filepath c:\temp\test.logAnd finally our log file contains the full content we want:
20151209132608: Get-ChildItem2 : The term 'Get-ChildItem2' is not recognized as the name of a cmdlet, function, script file, or
operable program. Check the spelling of the name, or if a path was included, verify that the path is correct and try
again.
At C:\Temp\test.ps1:3 char:7
+ $B = Get-ChildItem2 C:\temp
+ ~~~~~~~~~~~~~~
+ CategoryInfo : ObjectNotFound: (Get-ChildItem2:String) [], CommandNotFoundException
+ FullyQualifiedErrorId : CommandNotFoundException
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