Validating UNC Paths

Question

Consider the following PowerShell script:
while ($Path -eq $null -or $Path -eq '') {
$Path = Read-Host "Enter a local or UNC path"
if ((Test-Path $Path -PathType Container) -and ((Get-Item $Path).PSDrive.Provider.Name -eq "FileSystem")) {
Write-Host The path you entered is valid.
else {
Write-Host The path you entered is NOT valid.
Currently, it works as expected with local paths. However, valid UNC paths are considered invalid by this script. Also, I want it so that if a user accidentally puts "\\server" instead of "\\server\share", the script doesn't return the
following error message and then exit:
Test-Path : The UNC path should be of the form \\server\share.
How should I modify the code above to achieve this? Thanks!

Answer 1

It looks like that the following two methods have the same results
PS C:\> [bool]([System.Uri]$unc="\\server01\folder\file.txt").IsUnc
True
PS C:\> Test-Path -Path "\\server01\folder\file.txt" -IsValid
True
both Methods tests only if the syntax for an UNC Path is correct, but do not test if the path exist (or can be accessed)
I came to the following validation method:
Validate UNC Path
 Tested using PS 4.0 with Win 7
Using Test-Path cmdlet
Param (
    [Parameter(Position=0,Mandatory=$False,
HelpMessage="Enter a UNC path like \\server\share")]
    [ValidateScript({ Test-Path –Path $_ -IsValid })]
    [string]$unc = "\server01\My Share\folder"
NOTE:
Servername as full DNS Names is also valid, but  \\server01.com\\My dir\test.txt with ‘\\’ after the servername or after the sharename
 is also valid.
Spaces in the Path is allowed.
The –isValid Switch tests only if the path syntax is valid, not if the path really exist.
Using System.Uri class
Param (
    [Parameter(Position=0,Mandatory=$False,
HelpMessage="Enter a UNC path like \\server\share")]
    [ValidateScript({ [bool]([System.Uri]$_).IsUnc })]
    [string]$unc = "\server01\My Share\folder"
NOTE:
Servername as full DNS Names is also valid, but  "\\server01.com\\My dir\test.txt" with ‘\\’ after the servername or after the sharename
 is also valid.
Spaces in the Path is allowed. Test only if syntax is valid valid, not if the path really exist.
The same result as the Test-Path cmdlet with –isValid switch.
Using RegEx
Param (
 [Parameter(Position=0,Mandatory=$True,
   HelpMessage="Enter a UNC path like \\server\share")]
 [validatepattern({^\\\\\w+\\\w+})]
 [ValidateScript({Test-Path -Path $_ })]
 [string]$UNC_Path="\\server01\My share\folder"
# [string]$UNC_Path="\\server01\My share\folder\file.txt"
 is also valid
NOTE:
The regex pattern ‘^\\\\\w+\\\w+’ does not validate DNS servername like server.contoso.com
"\\server01.com\\My dir\test.txt"
 ‘\\’ after the servename or after the sharename is not allowed.
Test-Path used to test if the path really exist (or is accessible).
It depends what you want to validate and maybe return a specific Warning Message, I would do the test outside the Param() section.
Pasquale Lantella