AddToHosts.ps1

# By Tom Chantler - https://tomssl.com/2019/04/30/a-better-way-to-add-and-remove-windows-hosts-file-entries/
param([string]$DesiredIP = "127.0.0.1"
    ,[string]$Hostname = "tomssl.local"
	,[bool]$CheckHostnameOnly = $false)
# Adds entry to the hosts file.
#Requires -RunAsAdministrator
$hostsFilePath = "$($Env:WinDir)\system32\Drivers\etc\hosts"
$hostsFile = Get-Content $hostsFilePath

Write-Host "About to add $desiredIP for $Hostname to hosts file" -ForegroundColor Gray

$escapedHostname = [Regex]::Escape($Hostname)
$patternToMatch = If ($CheckHostnameOnly) { ".*\s+$escapedHostname.*" } Else { ".*$DesiredIP\s+$escapedHostname.*" }
If (($hostsFile) -match $patternToMatch)  {
    Write-Host $desiredIP.PadRight(20," ") "$Hostname - not adding; already in hosts file" -ForegroundColor DarkYellow
} 
Else {
    Write-Host $desiredIP.PadRight(20," ") "$Hostname - adding to hosts file... " -ForegroundColor Yellow -NoNewline
    Add-Content -Encoding UTF8  $hostsFilePath ("$DesiredIP".PadRight(20, " ") + "$Hostname")
    Write-Host " done"
}