Invoking Code Repeatedly

Sometimes you might want to run some command multiple times until it runs successfully. Here is a function that shows a way to do this:

#requires -Version 2
function Invoke-CodeRepeatedly
{
  param
  (
    [Parameter(Mandatory=$true)]
    $ScriptBlock,

    $RepeatCount = 4,
    $SleepMilliseconds = 3000

  )
  
  $c = 0
  do
  {  
    try
    {
      $ErrorActionPreference = 'Stop'
      & $ScriptBlock
      $doagain = $false
    }
    catch
    {
      $c++
      $doagain = $c -lt $RepeatCount 
      if ($doagain -eq $false) { break }
      Write-Verbose "Error $_ trying again..."
      Start-Sleep -Milliseconds $SleepMilliseconds
    }
  } while ($doagain)
}

You submit a script block with your code to Invoke-CodeRepeatedly and use -RepeatCount to specify how often the code should be tried. It repeats 4 times by default. -SleepMilliseconds is used to define the pause between tries. It waits for 3 seconds by default.

You could test this function like this:

Invoke-CodeRepeatedly -ScriptBlock { New-Item $env:temp\testfolder -ItemType Directory  } -Verbose

When you run it the first time, it succeeds and creates a new folder. When you run it later, it fails because the folder is already present. It will now try again three times (a total of 4 tries) and waits 3 seconds between each try. If you delete the folder from another PowerShell while the function runs, you will see the code succeed again.

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