Move File only if the file does not contain only a zero - powershell

Question

I have the below powershell command which, if the file only contains a zero and no spaces after, works ok.
However, my file has multiple spaces after the 0, followed by a newline.
How can I only move the file if the only character in the file is a 0, no matter on whether there are additional spaces and lines?
$file = Get-Content "Test\A28AP.txt" -raw
if ($file -notmatch '^0$') {
Move-Item "D:\Test\A28AP.txt" -Destination "D:\Test\History"
}

Answer 1

As Jeroen Mostert suggests, using .Trim() on the file's content before comparing to string '0' is the simplest solution in your case:
$filePath = 'Test\A28AP.txt'
if ('0' -ne (Get-Content $filePath -Raw).Trim()) {
Move-Item $filePath -Destination D:\Test\History -WhatIf
}
.Trim() (System.String.Trim) removes all leading and trailing whitespace, and is complemented by .TrimStart() and .TrimEnd() variants. All these methods optionally allow you to control the set of characters to be trimmed.
To look on the first line only, irrespective of whether there are additional, non-empty ones, replace -Raw with -First 1
For the sake of completeness, here's the equivalent (first-line-only) regex solution - even though it is overkill in your case:
$filePath = 'Test\A28AP.txt'
if ((Get-Content $filePath -First 1) -notmatch '^0 *') {
Move-Item $filePath -Destination D:\Test\History -WhatIf
}
' *' matches zero or more spaces after the 0 at the start of the string (^).
With a given multi-line input string (which is what -Raw returns for a multi-line file), limiting matching to the first line requires more effort:
By default, ^ and $ in .NET regexes match only the very beginning and end of the entire input; inline option (?m) can be used to make them match on each line, in which case \A and \Z / \z must be used to match the very beginning and end of the string - see the .NET regex quick reference.
Therefore, use regex '(?m)\A0 *$' to look for a 0 with optional trailing spaces only on the first line of the multi-line string:
$filePath = 'Test\A28AP.txt'
if ((Get-Content $filePath -Raw) -notmatch '(?m)\A0 *$') {
Move-Item $filePath -Destination D:\Test\History -WhatIf
}