Test-GCHostsFile.ps1
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<#
.SYNOPSIS Tests that the hosts file exists and is formatted correctly. .DESCRIPTION This test cmdlet performs two tasks: - Tests that the hosts file exists. - Checks the format of the hosts file. If both of these checks pass then True is returned. If either of these checks fail then False is returned. The format checks are performed using the following regular expression: '^$|^\s*$|^(\s*#.*)$|^((\s*[\d.:a-fA-F]+\s+[\w.]+\s*)(#+.*)*)$' This regular expression translates to the following: - Line is an empty line OR - Line is one or more spaces OR - Line has zero or more white space followed by a # OR - Line has zero or more white space followed by either digits, '.', ':', a-f, or A-F with white space followed by zero or more # .EXAMPLE This example returns True if the hosts file is in good condition. Test-GCHostsFile #> function Test-GCHostsFile { [CmdletBinding()] [Alias()] [OutputType([Boolean])] Param () $hostsFilePath = Join-Path -Path $env:SystemRoot -ChildPath 'System32\drivers\etc\hosts' $hostsFileExists = $false $hostsFileOk = $true $regexString = '^$|^\s*$|^(\s*#.*)$|^((\s*[\d.:a-fA-F]+\s+\w+\s*[\w.]*\s*)(#+.*)*)$' if (Test-Path -Path $hostsFilePath) { $hostsFileExists = $true } $hostsFileContent = Get-Content -Path $hostsFilePath foreach ($line in $hostsFileContent) { if ($line -notmatch $regexString) { $hostsFileOk = $false } } return $hostsFileExists -and $hostsFileOk } |