PowerShell: concatenate strings with variables after cmdlet

Question

I often find myself in the situation where I have to concatenate a string with a variable after a cmdlet. For example,

New-Item $archive_path + "logfile.txt" -type file

If I try to run this, PowerShell throws the following error:

New-Item : A positional parameter cannot be found that accepts argument '+'.

Am I not concatenating the string correctly? I'd like to not have to declare another variable before each cmdlet that I do this in (e.g., $logfile = $archive_path + "logfile.txt", and then do New-Item $logfile -type file). Also, I won't always be concatenating a file path.

Answer 1

You get that error because the PowerShell parser sees $archive_path, +, and "logfile.txt" as three separate parameter arguments, instead of as one string.

Enclose the string concatenation in parentheses, (), to change the order of evaluation:

New-Item ($archive_path + "logfile.txt") -Type file

Or enclose the variable in a subexpression:

New-Item "$($archive_path)logfile.txt" -Type file

You can read about argument mode parsing with Get-Help about_Parsing.