Powershell: Process contents of Directory

Hello!  I know it has been a while since I posted any thing.  I have been busy working on a lot of different projects and I picked up a second job so that has been keeping me busy as well.  

Todays post is mostly some powershell code to process Microsoft Document Imaging Files (.mdi or .tif) and converting them to PDF's using a program called MDI2PDF from Bugysoft.  

Part of our specific problem is these files are really Microsoft Document Imaging Files but they have the .tif file extenstion.  We wrote a PHP script to process all of our uploads from the one client that sends us these files and based on some tests we put the MDI Files into a specific directory for processing.

And now on to the Code.  Lines that start with a # are comments for explaining what each line / section does.

#Setting up variables for our use

         $input = "y:\allAuths\problemAuths\"

         $output = "y:\allAuths\processAuths\"

         $convert = "C:\Program Files\MDIConvertor\MDI2PDF.exe"

#Get the current number of errors present in the global $error variable.

     $olderrorcount = $error.count

#Check to see if MDI2PDF is running. If it is this script will fail, so we need to kill it.

       $proclist = get-process mdi2pdf -ea silentlycontinue

#If the number of errors is the same as is used to be then we can kill the running process(es).  Otherwise we have nothing to kill and continue on.

    if ($error.couint -eq $olderrorcount) {$proclist | stop-process}

#Here we get the contents of the input directory filtered for the type of file we want to convert.

      $filelist = get-childitem -Path $input -Filter *.tif

#For every file in our file list we need to run the following command in order from top to bottom.

     foreach ($file in $filelist)

     {

#Replaces the .tif with .pdf.

          $filename=$file -replace ($file.extension + "`$"),".pdf"

#Write something to the screen so the user knows something is happening.

       write-host "Converting $input$file"

#Look ma! Simple string concatenation!!!

#Roughly equal to &"C:\program files\mdiconvertor\mdi2pdf.exe export:y:\allauths\problemauths\.tif y:\allauths\processauths\.tif.pdf

         &$convert "export:$input$file $output$filename"

#get the process info for the currently running mdi2pdf process.

     $convertprocess = get-process mdi2pdf

#Wait for the process to exit before moving on to the next one. I used to use sleep 10 here but this is much better.

      $convertprocess.waitforexit()

#We need to check and make sure the converted file exists. If it does exist then we need to delete the original file.

    #variable to store the input filename. We will need this later to delete the file.

    $inputfile = $file.fullname

    #Variable to store the output filename and full path.  We use this later to check for its existance.

    $outputfile = $output + $filename

            #If the result of the path test is true we remove the file.

            if (test-path $outputfile)

            {remove-item $inputfile}

    }