All posts by Jim

Software engineer from Crete living in Switzerland; coffee addict; firearm lover; C# paladin; cryptography enthusiast; perpetually tormented by 3 beautiful women :-)

Find and kill processes that lock a file or directory

It’s an old problem when doing installations: some directory or file are locked by some process, and the installation fails.

As I’ve had this exact problem in the context of a web application, I’ve written this powershell script to take care of it. The idea was taken from the Octopus Deploy Blog.

So what the script does is:
downloads the Microsoft Handle utility (in %temp%)
– uses it to scan the $PathToCheck (can be a file or directory; if it’s a dir, it scans subdirs and all files as well)
parses the output
– if needed, kills all processes mentioned

#
# Source: DotJim blog (http://dandraka.com)
# Jim Andrakakis, August 2019
#
param([string]$PathToCheck = "c:\temp")

Clear-Host
$ErrorActionPreference = "Stop"

$url = "https://download.sysinternals.com/files/Handle.zip"

# === download handle.exe from microsoft ===
$tempDir = [System.IO.Path]::GetTempPath()
$handlePath = [System.IO.Path]::Combine($tempDir, "handle64.exe")
if (-not (Test-Path $handlePath)) {    
    $output = [System.IO.Path]::Combine($tempDir, "handle.zip")
    Invoke-WebRequest -Uri $url -OutFile $output
    Expand-Archive -LiteralPath $output -OutputPath $tempDir
}

# === run handle.exe ===
# see https://octopus.com/blog/how-to-handle-locked-files to see why the reg entry is needed
& reg.exe ADD "HKCU\Software\Sysinternals\Handle" /v EulaAccepted /t REG_DWORD /d 1 /f | Out-Null
$handleOutput = & $handlePath -a $PathToCheck

# === do we have to kill anything? ===
if ($handleOutput -match "no matching handles found") {
    Write-Host "Nothing to kill, exiting"
    exit
}

# === get process ids from handle.exe output ===
$pidList = New-Object System.Collections.ArrayList
$lines = $handleOutput | Split-String -RemoveEmptyStrings -separator "`n" 
foreach($line in $lines) {
  # sample line: 
  # chrome.exe         pid: 11392  type: File           5BC: C:\Windows\Fonts\timesbd.ttf
  # regex to get pid and process name: (.*)\b(?:.*)(?:pid: )(\d*)
  $matches = $null
  $line -match "(.*)\b(?:.*)(?:pid: )(\d*)" | Out-Null
  if (-not $matches) { continue }
  if ($matches.Count -eq 0) { continue }
  $pidName = $matches[1]
  $pidStr = $matches[2]
  if ($pidList -notcontains $pidStr) { 
    Write-Host "Will kill process $pidStr $pidName"
    $pidList.Add($pidStr) | Out-Null
  }
}

# === DIE PROCESS DIE ===
foreach($pidStr in $pidList) {
    $pidInt = [int]::Parse($pidStr)    
    Stop-Process -Id $pidInt -Force
    Write-Host "Killed process $pidInt"
}

Write-Host "Finished"

Hope that helps!

Σκεψεις για την “Τελευταια Μπλοφα”

Είμαι σε διακοπές, και όπου βρεθώ μια αγαπημένη συνήθεια είναι η επίσκεψη στο τοπικό βιβλιοπωλείο. Πάνω πάνω στα ευπώλητα ήταν το “Η τελευταία μπλόφα” της Ε. Βαρβιτσιώτη και Β. Δενδρινού. Το ειχα δει και τρέντινγκ στα σόσιαλ, ε το πήρα.

Το ρούφηξα σε λιγότερο από 24 ώρες. Και δεν είναι τόσο καλό όσο λένε, είναι ακόμη καλύτερο.

Παρότι ήξερα την ιστορία, σε ικανοποιητικό βαθμό, ως οικονομική και πολιτική, το βιβλίο την εξιστορεί από την προσωπική ματιά των πρωταγωνιστών. Αποτυπώνονται στιγμές που, για προφανείς λόγους, δεν είδαν το φως της δημοσιότητας όπως σύμβουλοι να απελπίζονται, πρωθυπουργοί να κοιμούνται σε καναπέδες, ο Ρέντσι να βάζει τις φωνές στη Μέρκελ και ο Ολάντ να πηδάει μπαλκόνια (!)

Αλλά δεν είναι κουτσομπολίστικο βιβλίο. Ίσα ίσα που δίνει την πίεση που είχαν όλοι -ή σχεδόν όλοι- να βρουν μια λύση σε μια κατάσταση που χάρη στην καταστροφική ανωριμότητα της τότε ελληνικής κυβέρνησης πήγε από το κακό στο χειρότερο σε χρόνο μηδέν.

Καταγραφω 2-3 σκέψεις, ιδέες και απορίες που έχω, τόσο για την ιστορία όσο και για το βιβλίο:

Η πρώτη και σίγουρα η σημαντικότερη: φαίνεται στο βιβλίο, αλλα ήταν και προφανές σε όσους παρακολουθήσαμε(*) αυτή την ιστορία, από τις αρχές μέχρι το φθινόπωρο του 2015, ότι η συμπεριφορά των εταίρων της Ελλάδας (χώρες ΕΕ, ΕΚΤ, ΔΝΤ κλπ.) ήταν πολύ ελαστικότερη προς την νέα τότε κυβέρνηση (ΣΥΡΙΖΑ-ΑΝΕΛ) παρά προς τις προηγούμενες (ΠΑΣΟΚ & ΝΔ-ΠΑΣΟΚ-ΔΗΜΑΡ). Κι αυτό όχι μόνο στην αρχή αλλά ακόμα και αργότερα, όταν είχε ήδη φανεί καθαρά ότι οι περισσότεροι άνθρωποι της νέας κυβέρνησης ήταν ιδεοληπτικοί, ανίκανοι για οποιαδήποτε σοβαρή εργασία τέτοιου μεγέθους και πολυπλοκότητας.

Γιατί;

Το βιβλίο δεν δίνει κάποια απάντηση. Σε κάποια σημεία μόνο διαφαίνεται, αν το ερμηνεύω σωστά, ότι με τις προηγούμενες κυβερνήσεις οι εταίροι είχαν αφενός μπουχτίσει με την απροθυμία τους να κάνουν τις επώδυνες αλλά αναγκαίες μεταρρυθμίσεις και αφετέρου τις θεωρούσαν -σωστά- υπεύθυνες για το χάλι της χώρας. Αν ισχύει αυτό, είναι στην ουσία παρόμοια λογική με το “τους είδαμε τους παλιούς, ας δοκιμάσουμε κάτι καινούριο” που έλεγαν αρκετοί πολίτες πριν τις εκλογές του 2015(**).

Η δεύτερη είναι οτι πρέπει να θυμόμαστε, όσοι δεν ασχολούμαστε ενεργά με την πολιτική, ότι η πολιτική κρίνεται από τα αποτελέσματά, όχι από τα λόγια. Είναι χαρακτηριστική η εικόνα της Μέρκελ που επισκέπτεται την Ελλάδα προ των εκλογών του 2015, βλέπει τα συνθήματα (“go back” κλπ) και, μετά τις εκλογές, δεν έχει κανένα πρόβλημα να συνεργαστεί με τους ίδιους που την καθύβριζαν.

Και η τρίτη, για το βιβλίο: θα ήταν χρήσιμο, σε κάποια επανέκδοση ίσως, να μπει ένα timeline, μια χρονική γραμμή που να δείχνει την αλληλουχία των γεγονότων. Ίσως ακόμα και δυο: μια από το 2009 ως το τέλος του 2015, που να δείχνει τα μείζονα γεγονότα (εκλογές 2009, Καστελόριζο, μνημόνιο 1, κυβέρνηση Παπαδήμου κλπ) και μια να κάνει ζουμ από την αρχή του 2015 ως το φθινόπωρο, με τα πάμπολλα Eurogroup, τα capital controls κλπ.

(*) την ελληνική κρίση την έζησα “άμεσα”, ζούσα και εργαζόμουν δηλαδή στην Ελλάδα, μέχρι την άνοιξη του 2012. Ήδη στα τέλη του 2011 είχα αποφασίσει ότι το ρίσκο για μένα, είτε λόγω grexit είτε πολύ απλά ότι μπορεί να έμενα άνεργος λόγω ύφεσης, ήταν πολύ υψηλό. Έτσι τον Φεβρουάριο του 2012 ξεκίνησα να ψάχνω για δουλειά στο εξωτερικό, και τέλη Απρίλη έμπαινα σε μια γκαρσονιέρα της Ζυρίχης. Από το φθινόπωρο 2012 και πέρα, παρότι φυσικά παρακολουθούσα τα πάντα με λεπτομέρεια, οι εξελίξεις δεν είχαν πάνω μου τις άμεσες συνέπειες που είχαν για τους φίλους μου -όσους δεν είχαν ήδη βγαλει εισητήριο χωρίς επιστροφή.

(**) το κυριότερο επιχείρημα όλων όσων τους έλεγα ότι οι ισχυρισμοί ΣΥΡΙΖΑ ήταν ανεδαφικοί (“θα καταργήσω τα μνημόνια μ’ένα νόμο κι ένα άρθρο” και άλλα ανεκδιήγητα), παρότι το καταλάβαιναν και το δεχόταν, ήταν “έστω και τα μισά από αυτά που υπόσχεται να κάνει, πάλι καλά θα είναι”. Αυτό… όπως είδαμε όλοι, δεν πήγε και πολύ καλά.

Powershell – file system operations within a transaction

Anyone who’s ever developed anything connected to a database knows about transactions. Using a transaction we can group data operations so that they happen “all or nothing”, i.e. either all of them succeed or no one does. One example is a transfer from one bank account to another: the complete transaction requires subtracting the amount to be transferred from one account and adding that same amount to the other. We wouldn’t want one to happen without the other, would we?

(yes, I know that’s not a complete description of what transactions are or do; that’s not my purpose here)

But what happens when we need the same from our filesystem?

Let’s take this scenario (which is a simplified version of a true story): we are receiving CSV files from solar panels (via SFTP) and we want to do some preprocessing and then store the data to a database. When processing them we have to generate a lot of intermediate files. After that, we want to move them to a different dir. But if something happens, say if the database is down, we want the whole thing to be cancelled so that, when we retry, we can start over.

Obviously a simple solution would be as follows:

try {
  # do a lot of hard work
  # store the data in the db
  # clean up intermediate files
  # move the CSV file to an "archive" dir
}
catch {
  # clean up intermediate files, potentially clean up any db records etc
}

That’s… well it can work but it’s not great. For example, the cleanup process itself -inside the catch block- might fail.

A much better process would be like that:

try {   
  # start a transaction
    # do a lot of hard work   
    # store the data in the db   
    # clean up intermediate files   
    # move the CSV file to an "archive" dir 
  # commit the transaction
} 
catch {   
  # rollback everything: files, db changes, the whole thing
}

That’s much cleaner! But is it possible to group db changes and filesystem changes (file create, move, delete & append, dir create & delete etc) all in one transaction?

Unix geeks are allowed to feel smug here: some flavors like HP-UX (though not Linux as far as I know) have this baked in from the get go. Your code doesn’t have to do anything special; the OS takes care of this on user request.

But as a matter of fact yes, it is also available on Windows, and it has been for some time now. The requirement is that you’re working on a file system that supports this, like NTFS.

But there’s a problem for the average .NET/Powershell coder: the standard methods, the ones inside System.IO, do not support any of this. So you have to go on a lower level, using the Windows API. Which for .NET coders, there’s no other way to put this, sucks. That’s also the reason why the Powershell implementation of file transactions (e.g. New-Item -ItemType File -UseTransaction) doesn’t work -it relies on System.IO.

I’m pretty sure that this is what crossed the minds of the developers that wrote AlphaFS which is just wonderful. It’s exactly what you’d expect but never got from Microsoft: a .NET implementation of most of System.IO classes that support NTFS’s advanced features that are not available in, say, ye olde FAT32. Chief among them is support for file system transactions.

So the example below shows how to do exactly that. I tried to keep it as simple as possible to highlight the interesting bits, but of course a real world example would be much more complicated, e.g. there would be a combined file system and database transaction, which would commit (or rollback) everything at the same time.

Note that there’s no need for an explicit rollback. As soon as the transaction scope object is disposed without calling Complete(), all changes are rolled back.

#
# Source: DotJim blog (http://dandraka.com)
# Jim Andrakakis, July 2019
#
# Prerequisite: 
#   1) internet connectivity
#   2) nuget command line must be installed 
#      (see https://www.nuget.org/downloads).
# If nuget is not in %path%, you need to change 
#   the installation (see below) to call it with 
#   its full path.
 
# Stop on error
$ErrorActionPreference = "Stop"

if ($psISE)
{
    $binPath = Split-Path -Path $PSISE.CurrentFile.FullPath        
}
else
{
    $binPath = $PSScriptRoot
}
$alphaFSver = "2.2.6"
$libPath = "$binPath\AlphaFS.$alphaFSver\lib\net40\AlphaFS.dll"
$basePath = "$binPath\..\alphatest"

# ====== installation ======
if (-not [System.IO.File]::Exists($libPath)) {
    Out-File -FilePath "$binPath\packages.config" `
        -Force `
        -Encoding utf8 `
        -InputObject ("<?xml version=`"1.0`" encoding=`"utf-8`"?&gt;<packages&gt;" + `
          "<package id=`"AlphaFS`" version=`"$alphaFSver`" targetFramework=`"net46`" /&gt;" + `
          "</packages&gt;")
    cd $binPath
    &amp; nuget.exe restore -PackagesDirectory "$binPath"
}
# ==========================
 
# Make sure the path matches the version from step 2
Import-Module -Name $libPath
 
if (-not (Test-Path $basePath)) {
    New-Item -ItemType Directory -Path $basePath
}
 
# Check if the filesystem we're writing to supports transactions.
# On a FAT32 drive you're out of luck.
$driveRoot = [System.IO.Path]::GetPathRoot($basePath)
$driveInfo = [Alphaleonis.Win32.Filesystem.DriveInfo]($driveRoot)
if (-not $driveInfo.VolumeInfo.SupportsTransactions) {
    Write-Error ("Your $driveRoot volume $($driveInfo.DosDeviceName) " + `
      "[$($driveInfo.VolumeLabel)] does not support transactions, exiting")
}
 
# That's some example data to play with.
# In reality you'll probably get data from a DB, a REST service etc.
$list = @{1="Jim"; 2="Stef"; 3="Elena"; 4="Eva"}
 
try {
    # Transaction starts here
    $transactionScope = [System.Transactions.TransactionScope]::new([System.Transactions.TransactionScopeOption]::RequiresNew)
    $fileTransaction = [Alphaleonis.Win32.Filesystem.KernelTransaction]::new([System.Transactions.Transaction]::Current)
 
    # Here we're doing random stuff with our files and dirs, 
    #   just to show how this works.
    # The important thing to remember is that for the transaction 
    #   to work correctly, ALL methods you use have to be -transacted.
    # I.e. you must not use AppendText() but AppendTextTransacted(), 
    #   not CreateDirectory() but CreateDirectoryTransacted() etc etc.
    $logfileStream = [Alphaleonis.Win32.Filesystem.File]::AppendTextTransacted($fileTransaction, "$basePath\list.txt")
    foreach($key in $list.Keys) {
        $value = $list.$key
        $filename = "$([guid]::NewGuid()).txt"
        $dir = "$basePath\$key"
 
        Write-Host "Processing item $key $value"
 
        if (-not [Alphaleonis.Win32.Filesystem.Directory]::ExistsTransacted($fileTransaction, $dir)) {
            [Alphaleonis.Win32.Filesystem.Directory]::CreateDirectoryTransacted($fileTransaction, $dir)
        }
        [Alphaleonis.Win32.Filesystem.File]::WriteAllTextTransacted($fileTransaction, "$basePath\$key\$filename", $value)        
        $logfileStream.WriteLine("$filename;$key;$value")
    }
    $logfileStream.Close()
     
    # to simulate an error and subsequent rollback:
    # Write-Error "Something not great, not terrible happened"
     
    # Commit transaction
    $transactionScope.Complete()
    Write-Host "Transaction committed, all modifications written to disk"
}
catch {
    Write-Host "An error occured and the transaction was rolled back: '$($_.Exception.Message)'"
    throw $_.Exception
}
finally {
    if ($null -ne $logfileStream -and $logfileStream -is [System.IDisposable]) {
        $logfileStream.Dispose()
        $logfileStream = $null
    }    
    if ($null -ne $transactionScope -and $transactionScope -is [System.IDisposable]) {
        $transactionScope.Dispose()
        $transactionScope = $null
    }    
}

Have fun coding!

Lefkogeia – a REST API test server

Lefkogeia is a server to test your REST APIs with. When it runs, it accepts every request made on the configured IP/port and returns an HTTP 200 “Thank you for your {method name, GET/POST etc}”. As you can imagine, I developed it for my own needs and then thought it would be handy for others, so I published it on Github.

You can download its first release here. The project’s intro page is here.

It logs all requests in a directory imaginatively called logs. It creates an access.txt file where all requests are written, and one file per request (000001.txt, 000002.txt etc) in which the request’s payload (e.g. an xml or a json) is written.

Usage

The primary use of Lefkogeia is to test/debug/troubleshoot REST API and web services clients. You run it (see release notes on that) and get your client to call it. It will log whatever was sent, allowing you to troubleshoot whatever problem you might have.

Configuration

To configure Lefkogeia, edit the appsettings.json file with a text editor.

An example appsettings.json file to serve multiple addresses & ports would be:

{
	"Logging": {
		"LogLevel": {
			"Default": "Debug",
			"System": "Information",
			"Microsoft": "Information"
		}
	},
	"Host": {
		"Url": [
			"http://localhost:6800",
			"http://server1:7777",
			"http://147.102.43.3:4545"
		]
	}
}

Paths are not yet supported in URLs, so if you change http://server1:7777 to http://server1:7777/testapi you will get an error. This is planned for the next release.

Also note that in order to use https:// you need to generate a certificate by running

dotnet dev-certs https --trust

For more info see https://go.microsoft.com/fwlink/?linkid=848054.

But why “Lefkogeia”, what does this even mean?

Because it’s such a beautiful place! Lefkogeia is a small village in southern Crete, Greece, with amazing beaches like Ammoudi, Shinaria, Klisidi and more. You can read more in Tripadvisor.

Bulk modify jobs in JAMS Scheduler

As I’ve mentioned before, at work we’re migrating all our scheduled tasks to JAMS. Now JAMS has a lot of flexibility to notify, sends emails etc but… you have to tell it to 🙂

And you can imagine that having to click-click-type-click in order to change, say, the email address in a few tens of jobs is not the creative work a developer craves for. Writing a powershell script to do that, though, is!

So here’s the script I wrote to change the email address for Warnings and Critical conditions, in bulk. Of course you can easily modify it to do whatever change you want (enable/disable a lot of jobs at once is a good example).

param(
    [string]$jamsServer = "myJamsServer", 
    [string]$jamsPath = "\somePath\someOtherPath"
)

# This script loops through all enabled JAMS jobs under a certain folder
# recursively, and changes the email address except for successes.

Import-Module Jams
$ErrorActionPreference = "Stop"
cls

try
{
    if ($null -eq (Get-PSDrive JD))
    {
        New-PSDrive JD JAMS $jamsServer -scope Local
    }
}
catch
{
    New-PSDrive JD JAMS $jamsServer -scope Local
}

$folders = New-Object System.Collections.ArrayList
$rootFolder = (Get-Item "JAMS::$($jamsServer)$($jamsPath)").Name
$folders.Add($rootFolder) | Out-Null
$childFolders = Get-ChildItem "JAMS::$($jamsServer)$($jamsPath)\*" -objecttype Folder -IgnorePredefined 
$childFolders | foreach { $folders.Add($_.Name) | Out-Null }

$rootJobs = New-Object System.Collections.ArrayList

foreach($f in $folders)
{
    Write-Host "Folder: $f"
    if ($f -eq $rootFolder)
    {
        $jobs = Get-ChildItem "JAMS::$($jamsServer)$($jamsPath)\*" -objecttype Job -IgnorePredefined -FullObject 
        $jobs | foreach { $rootJobs.Add($_.Name) | Out-Null }
    }
    else
    {
        $jobs = Get-ChildItem "JAMS::$($jamsServer)$($jamsPath)\$f\*" -objecttype Job -IgnorePredefined -FullObject 
    }

    # for test
    #$jobs | Format-Table -AutoSize

    foreach($job in $jobs)
    {
        #Write-Host "$($job.Name) : $($job.Properties["Enabled"])"
        #if you need a name filter as well, you can do:
        #if (($job.Name -notlike "*SomeString*") -or ($job.Properties["Enabled"].Value -eq $false))
        if ($job.Properties["Enabled"].Value -eq $false)
        {
            continue
        }

        $jobElements = $job.Elements
        $doUpdate = $false

        foreach($jobElement in $jobElements)
        {
            #Write-Host "$($job.Name) / $($jobElement.ElementTypeName) / $($jobElement.Description) / $($jobElement.ToString())"
            if (($jobElement.ElementTypeName -eq "SendEMail") -and ($jobElement.EntrySuccess -eq $false))
            {
                #Write-Host "$($job.Name) / $($jobElement.ElementTypeName) / $($jobElement.Description) / $($jobElement.FromAddress) / $($jobElement.ToAddress)"
                if ([string]::IsNullOrWhiteSpace($jobElement.ToAddress))
                {
                    $jobElement.FromAddress = "admin@superduperincrediblesoftware.com"
                    $jobElement.ToAddress = "someone@superduperincrediblesoftware.com;andhisdog@superduperincrediblesoftware.com"
                    $jobElement.MessageBody = "Uh, Houston, we've had a problem"      
                    $doUpdate = $true              
                }
            }
        }

        if ($doUpdate -eq $true)
        {
            $job.Update()
            Write-Host "Job $($job.Name) is updated"
        }
    }    
}

Have fun coding 🙂

Signs that you need coffee, #4

You go at the office machine and put an espresso cup in place, which can hold about 60 ml max.

You slide in an espresso capsule.

You press the “Large” button which, spoiler, produces around 110 ml coffee.

You stand in front of the machine in amazement while the coffee overflows the cup, wondering what went wrong.

You thank your good fortune that spared you the embarrassment as no colleague was in the company canteen at that time 🙂

Weird regional settings problems

If you’ve ever had to share files with data between different countries, you know that this can be problematic. For example, in Greece and the Netherlands the number “one thousand three hundred comma five” is written as “1 dot 300 comma 5”, in the UK it’s written as “1 comma 000 dot 5”, in Switzerland as “1 apostrophe 000 comma 5” etc etc. Same goes for dates.

So if you write software that is meant to be used in different countries, you have to be very careful and test thoroughly. And even then, you can run into problems. Just today I managed to solved a very weird one: Dutch-formatted numbers in an Excel file with Swiss settings caused an error message which, on the face of it, had nothing to do with formatting.

Y’know, 9/11 is the ninth of November in Greece

But the strangest, incomprehensible, 100% bang-your-head-on-the-wall problem I had was around 2005. My team wrote software that was meant to be multi-cultural and was used in Greece, Cyprus, Malta, Portugal, Turkey, Brasil and China (I may have missed a country or two after all these years).

So at some point me and my manager had to fly to Cyprus to test the software on-site; we went to a few of our customers and tried it out. And we were getting very, very, very strange error messages when doing simple, tried-and-true stuff. For a while we were flabbergasted.

After tearing my hair out and troubleshooting like crazy for hours on end, I noticed something which, while unusual, at first sight had nothing to do with our problems: our customers in Cyprus had set their Windows regional settings to use a dot as the thousand separator (according to the Greek settings) and… a dot (again) as the decimal separator (according to the UK settings).

Having tried virtually everything I changed it, just for the hell of it. I think I tried the normal Greek settings at first. And, like magic, everything was fixed! No errors whatsoever, everything ran smoothly!

You can imagine my astonishment.

I also tried a different setting (UK) and it was fine. I switched it back to the “special” Cyprus setting, and, sure enough, the problem started again. Now that I knew what to look for, I discovered that our software was “confused” (threw an error) when trying to understand just what kind of number 1 dot 234 dot 05 is.