Add YAML frontmatter to Markdown files. Obsidian Md.

add_frontmatter_to_md.ps1

$mdfiles = Get-ChildItem "." -Filter *.md

foreach($file in Get-ChildItem $mdfiles)
{
    Write-Output $file.BaseName
    $content = Get-Content $file.FullName -Raw
    $mddate = $file.BaseName
    $year = $mddate.Substring(0, 4)
    $month = $mddate.Substring(5, 2)

    $outtext = New-Object -TypeName System.Text.StringBuilder
    $outtext.Append("---`n")
    $outtext.Append("tags:`n")
    $outtext.Append("  - '#journal/$year/$month'`n")
    $outtext.Append("---`n")
    $outtext.Append("# $mddate`n")
    $outtext.Append("`n")
    $outtext.Append($content.ToString())
    # Set-Content -Path "$($file.FullName).bak" -value $outtext.ToString()
    Set-Content -Path "$($file.FullName)" -value $outtext.ToString()
}