How do I add a newline to command output in PowerShell?

I run the following code using PowerShell to get a list of add/remove programs from the registry:

Get-ChildItem -path hklm:\software\microsoft\windows\currentversion\uninstall `
    | ForEach-Object -Process { Write-Output $_.GetValue("DisplayName") } `
    | Out-File addrem.txt

I want the list to be separated by newlines per each program. I've tried:

Get-ChildItem -path hklm:\software\microsoft\windows\currentversion\uninstall `
    | ForEach-Object -Process { Write-Output $_.GetValue("DisplayName") `n } `
    | out-file test.txt

Get-ChildItem -path hklm:\software\microsoft\windows\currentversion\uninstall `
    | ForEach-Object {$_.GetValue("DisplayName") } `
    | Write-Host -Separator `n

Get-ChildItem -path hklm:\software\microsoft\windows\currentversion\uninstall `
    | ForEach-Object -Process { $_.GetValue("DisplayName") } `
    | foreach($_) { echo $_ `n }

But all result in weird formatting when output to the console, and with three square characters after each line when output to a file. I tried Format-List, Format-Table, and Format-Wide with no luck. Originally, I thought something like this would work:

Get-ChildItem -path hklm:\software\microsoft\windows\currentversion\uninstall `
    | ForEach-Object -Process { "$_.GetValue("DisplayName") `n" }

But that just gave me an error.

Or, just set the output field separator (OFS) to double newlines, and then make sure you get a string when you send it to file:

$OFS = "`r`n`r`n"
"$( gci -path hklm:\software\microsoft\windows\currentversion\uninstall | 
    ForEach-Object -Process { write-output $_.GetValue('DisplayName') } )" | 
 out-file addrem.txt

Beware to use the ` and not the '. On my keyboard (US-English Qwerty layout) it's located left of the 1.
(Moved here from the comments - Thanks Koen Zomers)

Give this a try:

PS> $nl = [Environment]::NewLine
PS> gci hklm:\software\microsoft\windows\currentversion\uninstall | 
        ForEach { $_.GetValue("DisplayName") } | Where {$_} | Sort |
        Foreach {"$_$nl"} | Out-File addrem.txt -Enc ascii

It yields the following text in my addrem.txt file:

Adobe AIR

Adobe Flash Player 10 ActiveX

...

Note: on my system, GetValue("DisplayName") returns null for some entries, so I filter those out. BTW, you were close with this:

ForEach-Object -Process { "$_.GetValue("DisplayName") `n" }

Except that within a string, if you need to access a property of a variable, that is, "evaluate an expression", then you need to use subexpression syntax like so:

Foreach-Object -Process { "$($_.GetValue('DisplayName'))`r`n" }

Essentially within a double quoted string PowerShell will expand variables like $_, but it won't evaluate expressions unless you put the expression within a subexpression using this syntax:

$(`<Multiple statements can go in here`>).

I think you had the correct idea with your last example. You only got an error because you were trying to put quotes inside an already quoted string. This will fix it:

gci -path hklm:\software\microsoft\windows\currentversion\uninstall | ForEach-Object -Process { write-output ($_.GetValue("DisplayName") + "`n") }

Edit: Keith's $() operator actually creates a better syntax (I always forget about this one). You can also escape quotes inside quotes as so:

gci -path hklm:\software\microsoft\windows\currentversion\uninstall | ForEach-Object -Process { write-output "$($_.GetValue(`"DisplayName`"))`n" }

Ultimately, what you're trying to do with the EXTRA blank lines between each one is a little confusing :)

I think what you really want to do is use Get-ItemProperty. You'll get errors when values are missing, but you can suppress them with -ErrorAction 0 or just leave them as reminders. Because the Registry provider returns extra properties, you'll want to stick in a Select-Object that uses the same properties as the Get-Properties.

Then if you want each property on a line with a blank line between, use Format-List (otherwise, use Format-Table to get one per line).

gci -path hklm:\software\microsoft\windows\currentversion\uninstall |
gp -Name DisplayName, InstallDate | 
select DisplayName, InstallDate | 
fl | out-file addrem.txt

The option that I tend to use, mostly because it's simple and I don't have to think, is using Write-Output as below. Write-Output will put an EOL marker in the string for you and you can simply output the finished string.

Write-Output $stringThatNeedsEOLMarker | Out-File -FilePath PathToFile -Append

Alternatively, you could also just build the entire string using Write-Output and then push the finished string into Out-File.