Converting a line of cmd to powershell - powershell

Question

EDIT2: Final code below
I need help on converting some codes as I am very new to mkvmerge, powershell and command prompt.
The CMD code is from https://github.com/Serede/mkvtoolnix-batch/blob/master/mkvtoolnix-batch.bat
for %%f in (*.mkv) do %mkvmerge% #options.json -o "mkvmerge_out/%%f" "%%f"
What I've managed so far
$SourceFolder = "C:\tmp" #In my actual code, this is done using folder browser
$SourceFiles = Get-ChildItem -LiteralPath $SourceFolder -File -Include *.mkv
$SourceFiles | foreach
{
start-process "F:\Desktop\#progs\mkvtoolnix\mkvmerge.exe"
}
I'd be grateful for any help as I'm having trouble understanding and converting while learning both sides. Thank you very much.
**EDIT 2:**Here's my final working code.
Function Get-Folder($initialDirectory) {
#Prompt to choose source folder
[void] [System.Reflection.Assembly]::LoadWithPartialName('System.Windows.Forms')
$FolderBrowserDialog = New-Object System.Windows.Forms.FolderBrowserDialog
$FolderBrowserDialog.Description = 'Choose the video folder'
$FolderBrowserDialog.RootFolder = 'MyComputer'
if ($initialDirectory) { $FolderBrowserDialog.SelectedPath = $initialDirectory }
[void] $FolderBrowserDialog.ShowDialog()
return $FolderBrowserDialog.SelectedPath
}
Function ExitMessage
{
#endregion Function output
Write-Host "`nOperation complete";
Write-Host -NoNewLine 'Press any key to continue...';
$null = $Host.UI.RawUI.ReadKey('NoEcho,IncludeKeyDown');
Exit;
}
($SourceFolder = Get-Folder | select )
#Check for output folder and create if unavailable
$TestFile = "$SourceFolder" + "\mkvmerge_out"
if ((Test-Path -LiteralPath $TestFile) -like "False")
{
new-item -Path $SourceFolder -name "mkvmerge_out" -type directory
Write-Host 'Folder created';
}
#Checking for the presence of a Json file
$TestFile = (Get-ChildItem -LiteralPath $SourceFolder -File -Filter *.json)
if ($TestFile.count -eq 0)
{
Write-Host 'json file not found';
ExitMessage;
}
$TestFile = "$SourceFolder" + "\$TestFile"
#Getting the total number of files and start timer.
[Int] $TotalFiles = 0;
[Int] $FilesDone = 0;
$TotalFiles = (Get-ChildItem -LiteralPath $SourceFolder -File -Filter *.mkv).count
$PercentFiles = 0;
$Time = [System.Diagnostics.Stopwatch]::StartNew()
#Start mkvmerge process with progress bar
$mkvmergeExe = 'F:\Desktop\#progs\mkvtoolnix\mkvmerge.exe'
$JsonFile = "$TestFile" # alternatively, use Join-Path
Get-ChildItem -LiteralPath $SourceFolder -File -Filter *.mkv | ForEach-Object {
$PercentFiles = [math]::truncate(($FilesDone/$TotalFiles)*100)
Write-Progress -Activity mkvmerge -Status ("{0}% Completed; {1}/{2} done; Time Elapsed: {3:d2}:{4:d2}:{5:d2}" -f $PercentFiles, $FilesDone, $TotalFiles, $Time.Elapsed.Hours, $Time.Elapsed.minutes, $Time.Elapsed.seconds) -PercentComplete $PercentFiles;
Write-Host "Processing $_"
$f = $_.FullName
$of = "$SourceFolder\mkvmerge_out\$($_.Name)"
& $mkvmergeExe -q `#$JsonFile -o $of $f
$FilesDone++
}
Remove-Item -LiteralPath $JsonFile #Remove this line if you want to keep the Json file
$PercentFiles = [math]::truncate(($FilesDone/$TotalFiles)*100)
Write-Progress -Activity mkvmerge -Status ("{0}% Completed; {1}/{2} done; Time Elapsed: {3:d2}:{4:d2}:{5:d2}" -f $PercentFiles, $FilesDone, $TotalFiles, $Time.Elapsed.Hours, $Time.Elapsed.minutes, $Time.Elapsed.seconds) -PercentComplete $PercentFiles;
ExitMessage;

Answer 1

$mkvmergeExe = 'F:\Desktop\#progs\mkvtoolnix\mkvmerge.exe'
$optionsFile = "$SourceFolder\options.json" # alternatively, use Join-Path
Get-ChildItem -LiteralPath $SourceFolder -File -Filter *.mkv | ForEach-Object {
$f = $_.FullName
$of = "$SourceFolder\mkvmerge_out\$($_.Name)"
& $mkvmergeExe `#$optionsFile -o $of $f
}
Note that your cmd code assumes that it's operating in the current directory, while your PowerShell code passes a directory explicitly via $SourceFolder; therefore, the options.json file must be looked for in $SourceFolder and too, and the output file path passed to -o must be prefixed with $SourceFolder too which is achieved via expandable strings ("...") .
The main points to consider:
for %%f in (*.mkv) has no direct counterpart in PowerShell; you correctly used Get-ChildItem instead, to get a list of matching files, which are returned as System.IO.FileInfo instances.
However, -Include won't work as intended in the absence of -Recurse (unless you append \* - see this GitHub issue; -Filter does, and is also the faster method, but it has its limitations and legacy quirks (see this answer).
While PowerShell too allows you to execute commands whose names or paths are stored in a variable (or specified as a quoted string literal), you then need &, the call operator, to invoke it, for syntactic reasons.
Inside a script block ({ ... }) passed to the ForEach-Object cmdlet, automatic variable $_ represents the pipeline input object at hand.
$_.FullName ensures that the System.IO.FileInfo input instances are represented by their full path when used in a string context.
This extra step is no longer necessary in PowerShell [Core] 6+, where System.IO.FileInfo instances thankfully always stringify as their full paths.
The # character is preceded by ` (backtick), PowerShell's escape character, because # - unlike in cmd - is a metacharacter, i.e. a character with special syntactic meaning. `# ensures that the # is treated verbatim, and therefore passed through to mkvmerge.
Alternatively, you could have quoted the argument instead of escaping just the #: "#$optionsFile"
See this answer for background information.
You generally do not need to enclose arguments in "..." in PowerShell, even if they contain spaces or other metacharacters.