CODEWITHSUNDEEP
powershell
dcaz
dcaz

Reputation: 909

Try / Catch or Error Variable and using either

I am wondering if the Try / Catch below works or should I use an IF ($problem) instead of the Try/Catch

Try {
    New-Item -Path C:\reports -ItemType Directory -ErrorAction SilentlyContinue -ErrorVariable Problem -Force
}
Catch {
    Write-Warning "Problem with C:\Report directory. Unable to create report $Type of $SourceEmail $Flag $DestinationEmail"
}

I am checking to see if a directory exists and if not attempt to create the directory. I am not sure if because I am using -ErrorAction SilentlyContinue -ErrorVariable Problem the try/catch is not working as intended?

Altenative

 New-Item -Path C:\reports -ItemType Directory -ErrorAction SilentlyContinue -ErrorVariable Problem -Force
 If ($Problem) {
  Write-Warning "Problem trying to create C:\Reports."
 }

Upvotes: 2

Views: 1652

Answers (1)

mklement0
mklement0

Reputation: 437478

I am checking to see if a directory exists and if not attempt to create the directory.

New-Item's -Force switch can be used to create a directory unless it already exists; a System.IO.DirectoryInfo object describing either the preexisting directory or the newly created directory is returned (note that -Force also creates parent directories on demand).

Since you're already using -Force, this means that only a true error condition is reported, such as a lack of permissions.

In the simplest case, you can simply abort your script when such an error condition occurs, using -ErrorAction Stop to convert the (first) non-terminating error that New-Item reports to a script-terminating one:

$targetDir = New-Item -Force -ErrorAction Stop -Path C:\reports -ItemType Directory

If an error occurs, it will be printed, and the script will be aborted.

If you want to capture errors and perform custom actions, you have two mutually exclusive options:

  • Capture the non-terminating error in variable $Problem, via -ErrorVariable Problem, and act on the value of $Problem afterwards; -ErrorAction SilentlyContinue suppresses display of the error:[1]
$targetDir = New-Item -Force -ErrorAction SilentlyContinue -ErrorVariable Problem -Path C:\reports -ItemType Directory

if ($Problem) { 
  Write-Warning "Problem trying to create C:\Reports: $Problem"
  # Exit here, if needed.
  exit 1
}
  • Promote the (first) non-terminating error to a script-terminating one via -ErrorAction Stop and use a try { ... } catch { ... } statement to catch it, in whose catch block $_ refers to the error at hand:
try {
  $targetDir = New-Item -Force -ErrorAction Stop -Path C:\reports -ItemType Directory
} catch {
  $Problem = $_
  Write-Warning "Problem trying to create C:\Reports: $Problem"
  # Exit here, if needed.
  exit 1
}

For a comprehensive overview of PowerShell's surprisingly complex error handling, see this GitHub docs issue.

[1] This makes the capturing of the error via -ErrorVariable silent; do not use -ErrorAction Ignore, as that will render -ErrorVariable ineffective.

Upvotes: 5

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