kb / PowerShell

Change file’s “Date Modified”

You’ll most likely provide a date in YYYY,MM,DD or YYYY,MM,DD,HH,MM,SS format, but you can use any DateTime constructor.

(Get-Item '.\path\to.item').LastWriteTime = New-Object DateTime 2019,10,27, 21,24,56

Hash a file

(Get-FileHash '.\ngl-pretty-sus.rar' -Algorithm MD5).Hash

Where .\ngl-pretty-sus.rar is the filepath to the file to hash. Algorithms supported are SHA1, SHA256, (default), SHA384, SHA512, and MD5.

Split string on a string

String.Split() works on just a single character, but the -Split operator uses regular expressions by default.

Remove line from files

Get-ChildItem "path\to\folder" -Filter *.htm | 
Foreach-Object {
    $content = Get-Content $_.FullName # Temp variable needed to prevent simultaneous access
    $content | Select-String -SimpleMatch 'String you want to remove' -NotMatch | Set-Content $_.FullName
}

You can also swap -SimpleMatch with -Pattern if you want to use regular expressions.

View function source code

${function:Get-FileHash}

Function: is a virtual volume full of strings.

Remove a property from an object

Let’s say we have this object:

$demo = [PSCustomObject] @{
    Foo="foo"
    Bar="bar"
}

It looks like this when we output it:

PS> $demo

Foo Bar
--- ---
foo bar

To remove the property:

$a.PSObject.Properties.Remove("Bar")

Now it’s gone:

$demo

Foo
---
foo

However if a custom type was set on this object, that can (but not always) override what gets shown with Get-Output:

 $demo.PSObject.TypeNames.Insert(0, "System.String")
 $demo

@{Foo=foo}

$demo.PSObject.TypeNames.Insert(0, "Microsoft.Powershell.Utility.FileHash")
$demo

Algorithm       Hash                                                                   Path
---------       ----                                                                   ----

Sometimes output is deferred to something lower in the types stack:

$demo.PSObject.TypeNames.Insert(0, "System.IO.File")
$demo

Algorithm       Hash                                                                   Path
---------       ----                                                                   ----

Sometimes it isn’t:

$demo.PSObject.TypeNames.Insert(0, "System.String")
$demo

@{Foo=foo}

Sometimes it forgets again:

$demo.PSObject.TypeNames.Insert(0, "System.IO.File")
$demo

Algorithm       Hash                                                                   Path
---------       ----                                                                   ----

If late binding gets in the way you’re better off making a custom object.