Pathing in Powershell - powershell

Question

My corrent Code is this
Add-Type #"
using System;
using System.Runtime.InteropServices;
using Microsoft.Win32;
namespace Wallpaper
{
public enum Style : int
{
Tile, Center, Stretch, NoChange
}
public class Setter {
public const int SetDesktopWallpaper = 20;
public const int UpdateIniFile = 0x01;
public const int SendWinIniChange = 0x02;
[DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
private static extern int SystemParametersInfo (int uAction, int uParam, string lpvParam, int fuWinIni);
public static void SetWallpaper ( string path, Wallpaper.Style style ) {
SystemParametersInfo( SetDesktopWallpaper, 0, path, UpdateIniFile | SendWinIniChange );
RegistryKey key = Registry.CurrentUser.OpenSubKey("Control Panel\\Desktop", true);
switch( style )
{
case Style.Stretch :
key.SetValue(#"WallpaperStyle", "2") ;
key.SetValue(#"TileWallpaper", "0") ;
break;
case Style.Center :
key.SetValue(#"WallpaperStyle", "1") ;
key.SetValue(#"TileWallpaper", "0") ;
break;
case Style.Tile :
key.SetValue(#"WallpaperStyle", "1") ;
key.SetValue(#"TileWallpaper", "1") ;
break;
case Style.NoChange :
break;
}
key.Close();
}
}
}
"#
[Wallpaper.Setter]::SetWallpaper( 'C:\Users\God\Desktop\Test\God.bmp' , 0 )
Ok, the Script comes with the God.bmp, which are ALWAYS in the same
directory (Folder Test on Desktop right now), I tried to replace the Path "C:\Users\God\Desktop\Test\God.bmp" With ".\God.bmp" which should work but it doesent seem to work I tried "./God.bmp" aswell but the Background turns black and not into the God picture. So how can I make it work because normally .\ makes it use the current Path as far as i know

Answer 1

Probably Windows doesn't handle relative paths to wallpaper in registry. If you'd like to use relative paths in your code, you have to expand them to full paths before writing to the registry:
$FullPath = Join-Path -Path (Get-Location -PSProvider FileSystem).Path -ChildPath 'God.bmp'
[Wallpaper.Setter]::SetWallpaper($FullPath , 0)

Answer 2

PowerShell will try to find .\God.bmp relative to where the caller is, not where the executing script exists in the filesystem.
Try this simple example:
# C:\scripts\relativepath.ps1
[System.IO.Path]::GetFullPath(".\god.bmp")
If you open a prompt and cd to C:\scripts, it works as expected:
PS C:\scripts> .\relativepath.ps1
C:\scripts\god.bmp
But if you change to another directory:
PS C:\somewhere\else> C:\scripts\relativepath.ps1
C:\somewhere\else\god.bmp
If you want the full path relative to where the executing script is located, use the $PSScriptRoot automatic variable:
$WallPaperPath = Join-Path -Path $PSScriptRoot -ChildPath "god.bmp"