Date formatted using ToString() with a custom format results in inconsistent output-CodePudding

with a powershell script I'm exporting a list of all the DHCP Servers that exists and the scopes on the Server. The results has to be parsed in a second script in python. (Thats a system for our monitoring).

Here's the script:

$DHCPServers = (Get-DhcpServerInDC).Dnsname
$Scopes = @()
$Leases = @()
foreach ($DHCPServer in $DHCPServers) {
    $Scopes  = Get-DhcpServerv4Scope -ComputerName $DHCPServer | select-Object @{Name="DHCPServer"; Expression = {$DHCPServer}},ScopeID,Name,StartRange,EndRange
}

$Scopes | Export-Csv -path .\DHCP_Freeleases-Scopes-get.csv -Encoding utf8 -NoTypeInformation

foreach ($Scope in $Scopes) {
    $Leases  = Get-DHCPServerv4Lease -ScopeId $Scope.ScopeID -ComputerName $Scope.DHCPServer | select-Object @{Name="DHCPServer"; Expression = {$Scope.DHCPServer}}, IPAddress, @{Name="LeaseExpiryTime"; Expression = {$_.LeaseExpiryTime.toString("yyyy/MM/dd/HH:mm")}}, @{Name="ScopeID"; Expression = {$Scope.ScopeID}}, Addressstate
}

$Leases | Export-Csv -path .\DHCP_Freeleases-Leases-get.csv -Encoding utf8 -NoTypeInformation

While I wrote that script on my local DHCP Server (Windows Server 2012 R2) the CSV export was the way that I wanted it:

"dhcp1.server.intern","10.26.9.202","2022/01/25/08:22","172.26.9.192","Active"

Now I deployed the script to a different server (Windows Server 2019) and the exact same script gives me this CSVline:

"dhcp1.server.intern","10.26.9.202","2022.01.25.08:22","172.26.9.192","Active"

And I want to understand it: How can that be? I thought .toString() gives it out with my parameters?

Thanks for you help!

CodePudding user response：

The DateTime.ToString() method treats the forward slash and the colon as format specifiers. This means that they can be replaced by locale-specific characters.

From the documentation:

The "d", "f", "F", "g", "h", "H", "K", "m", "M", "s", "t", "y", "z", ":", or "/" characters in a format string are interpreted as custom format specifiers rather than as literal characters. To prevent a character from being interpreted as a format specifier, you can precede it with a backslash (), which is the escape character.

To enforce a fixed format just escape these characters by backslashes:

$_.LeaseExpiryTime.toString("yyyy\/MM\/dd\/HH\:mm")

As you noted in the comments, you may also use a predefined format, such as 's' (ISO 8601), that is locale-independent by definition:

$_.LeaseExpiryTime.toString('s')

The output looks like 2022-01-25T11:20:26.