Programming

Do you ever have the problem where you start a long running script (such as running a code build), multi-task on something else on another monitor while waiting for the script to finish, and then totally forget about the script until half an hour later? Well, here’s a solution your problem: have your script give you holler at you when it’s done.

In my library script file, I have the following functions to play sound files and to speak any text:

function PlayMp3($path) {
    # Use the default player to play. Hide the window.
    $si = new-object System.Diagnostics.ProcessStartInfo
    $si.fileName = $path
    $si.windowStyle = [System.Diagnostics.ProcessWindowStyle]::Hidden
    $process = New-Object System.Diagnostics.Process
    $process.startInfo=$si
    $process.start() 
}

function PlayWav($path) {
    $sound = new-Object System.Media.SoundPlayer;
    $sound.SoundLocation="$path";
    $sound.Play();
}

function Say($msg) {
    $Voice = new-object -com SAPI.SpVoice
    $Voice.Speak($msg, 1 )
}

If you like the text-to-speech feature but find Windows’ speech engine lacking, check out Ivona. It’s a commercial text-to-speech engine but you are allow to generate and download short speech files for free personal use. Now, my script can nicely interrupt me to tell me when it’s done. Other online text-to-speech engines: vozMe, SpokenText.

If Making Noise Is Not Your Thing

If making noise is not your thing, consider displaying a message in the Notification Area. Here’s the code (courtesy Microsoft TechNet):

function Get-ScriptName {
    $MyInvocation.ScriptName
} 

function DisplayNotificationInfo($msg, $title, $type) {
    # $type - "info" or "error"
    if ($type -eq $null) {$type = "info"}
    if ($title -eq $null) {$title = Get-ScriptName}

    [void] [System.Reflection.Assembly]::LoadWithPartialName("System.Windows.Forms")
    $objNotifyIcon = New-Object System.Windows.Forms.NotifyIcon 
    # Specify your own icon below
    $objNotifyIcon.Icon = "C:CdoScriptsFolder.ico"
    $objNotifyIcon.BalloonTipIcon = "Info"  
    $objNotifyIcon.BalloonTipTitle = $title
    $objNotifyIcon.BalloonTipText = $msg

    $objNotifyIcon.Visible = $True 
    $objNotifyIcon.ShowBalloonTip(10000)
}

I found out the hard way that mvn (Maven) on Windows always return a success code of true, which means you cannot use the return code ($?) to check whether the mvn command succeeded or failed. Why they decided to break this seemingly basic program contract is a mystery. A work-around is to scan the mvn output and look for specific strings such as “BUILD SUCCESSFUL”.

Here’s how:

function InvokeAndCheckStdOut($cmd, $successString, $failString) {
    Write-Host "====> InvokeAndCheckStdOut"
    $fullCmd = "$cmd|Tee-Object -variable result" 

    Invoke-Expression $fullCmd
    $found = $false
    $success = $false
    foreach ($line in $result) {
      if ($line -match $failString) {
       $found = $true
       $success = $false
       break
      }
      else {
       if ($line -match $successString) {
        $found = $true
        $success = $true
        #"[InvokeAndCheckStdOut] FOUND MATCH: $line"
        break
       }
       else {
        #"[InvokeAndCheckStdOut] $line"
       }
      }
    }

    if (! $success) {
      PlayWav "${env:windir}\Media\ding.wav"
      throw "Mvn command failed."
    }

    Write-Host "InvokeAndCheckStdOut <===="
}

function InvokeMvn($cmd) {
    InvokeAndCheckStdOut $cmd "BUILD SUCCESSFUL" "BUILD FAILED"
}


InvokeMvn "mvn clean install"

See Also

• Tee-Object and Invoke-Expression in PowerShell

The PowerShell Tee-Object Cmdlet allows you to send command output to a file or a variable, and display it in the console at the same time. This is very useful for those instances where you need to parse the text output of a command. I had a hard time getting it to work with Invoke-Expression. After trying different things, I finally found the solution. To get Tee-Object to work with Invoke-Expression in PowerShell 1, include the Tee command in the Invoke-Expression command like this:

Invoke-Expression "mvn clean install | Tee –variable result”

The following, which I guess is what most people try first, doesn’t work (at least in PowerShell V1). I guess because you are storing the result of the “Invoke-Expression” command itself into the variable instead of “mvn clean install”.

    Invoke-Expression "mvn clean install” | Tee -variable result

Wrapping Invoke-Expression in parenthesis (see below) works, but has a drawback: the output is not written to Standard Out until the whole command finishes.

    (Invoke-Expression "mvn clean install”) | Tee -variable result

$tempFile = [IO.Path]::GetTempFileName()

An empty file created immediately when you call this method. Remember to clean it up when are you done!