How do I get a list of all files (recursively) that don't contain a specific string? Thank you, Ittay

One way:

Get-ChildItem -Filter *.txt -Recurse | Where-Object { [io.file]::ReadAllText($_.FullName) -notmatch 'pattern' }

Or:

Get-ChildItem -Filter *.txt -Recurse | Where-Object { !(Select-String -Path $_.fullname -Pattern 'pattern' -SimpleMatch -Quiet)}

Thanks!

And if I want to get a flat list of all file names?

Pipe the results to foreach-object and choose one of:
1. $_.Name (file name only)
2. $_.FullName (full path)

Get-ChildItem -Filter *.txt -Recurse | Where-Object { !(Select-String -Path $_.fullname -Pattern 'pattern' -SimpleMatch -Quiet)} | Foreach-Object {$_.Name}