Powershell Get-Content - variable File

Question

I need to change the encoding of a file from UTF8-BOM to UTF8 different files where the date is different. I have a variable with the Data that I need but I have problems passing that variable to the Get-Content param.

$Today = Get-Date -Format "yyyyMMdd"
Get-Content 'D:\Folder_1\Test_file.'+$(${Today})+'.csv' | Set-Content -Encoding Ascii 'D:\Folder_2\Test_file.'+$(${Today})+'.csv'

The file names are "Test_file.20220923.csv" for example.

The error:

Get-Content : A positional parameter cannot be found that accepts argument '+20220923+.

Answer 1

• 'D:\Folder_1\Test_file.'+$(${Today})+'.csv' is an expression (a string concatenation via the + operator).

• In order to pass an expression as an argument to a command, you must enclose it in (...), the grouping operator.^[1]

Therefore (applies analogously to your Set-Content call):

Get-Content ('D:\Folder_1\Test_file.'+${Today}+'.csv')

Note that I've omitted the unnecessary use of $(...), the subexpression operator, which is typically only needed inside expandable (double-quoted) string ("..."), and then only for embedding expressions or commands (a variable reference such as $Today by itself can be embedded as-is).

The equivalent command using an expandable string:

Get-Content "D:\Folder_1\Test_file.${Today}.csv"

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As for what you tried:

# WRONG: Passes *two* arguments.
Get-Content 'D:\Folder_1\Test_file.'+$(${Today})+'.csv'

Even though 'D:\Folder_1\Test_file.'+$(${Today})+'.csv' contains no spaces, PowerShell breaks this compound token into two arguments, verbatim D:\Folder_1\Test_file. and (for instance) verbatim +20220923+.csv.^[2]

It is the latter, i.e. the extra positional argument causes Get-Content to report an error, because it only supports one positional argument (which binds to its -Path parameter).

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^{[1] $(...) is often seen in practice instead, but $(...) is only ever needed in two cases: (a) to embed entire statement(s), notably loops and conditionals, in another statement, and (b) to embed an expression, command, or statement(s) inside "...", an expandable (interpolating) string. Just (...) is enough to pass a single command or expression as a command argument. While not likely, the unnecessary use of $(...) can have side effects - see this answer.}

^{[2] In case you're wondering how a compound token such as 'D:\Folder_1\Test_file.'+${Today}+'.csv' is parsed and results in these two arguments, see this answer.}