How to select a substring in select/group command- Powershell - powershell

Question

In the code below, the userprinciplename will output strings like "LLL_John.Smith#email.com" and XXXX_Jane.Doe#email.com" but i am hoping to extract a substring from that, that being the codes before the "_" character, so LLL and XXXX.
There may be some which do not have an underscore character however and so these would need to be ignored / have the original string it would have returned.
##Check bottom of script for setting specific OU
Function Get-LastLogon {
param(
[string]$OUName
)
# Get all matching OUs on any level
$OUs = Get-ADOrganizationalUnit -Filter "Name -like '$OUName'"
$DCs = Get-ADDomainController -Filter *
# Get all users from each OU from each DC
$ADUsers = Foreach ($OU in $OUs) {
Foreach ($DC in $DCs.HostName) {
Get-ADUser -SearchBase $OU.DistinguishedName -Filter * -Properties LastLogon -server $dc |
Select-Object Name,userPrincipalName, #{n='LastLogon';e={[DateTime]::FromFileTime($_.LastLogon)}}
}
}
# return most recent LastLogon date for each user
$ADUsers |
Group Name,userPrincipalName |
Select Name,userprinciplename, #{n='LastLogon';e={$_.Group.LastLogon | sort -desc | select -First 1}}
} ## End function
##Enter the OU here
Get-LastLogon -OUName 'Clients'
##Un-comment below to export to csv
## | Export-Csv -Path 'C:\temp\UserExport.csv'
Here is what the script looks like now in full:
##Check bottom of script for setting specific OU
Function Get-LastLogon {
param(
[string]$OUName
)
# Get all matching OUs on any level
$OUs = Get-ADOrganizationalUnit -Filter "Name -like '$OUName'"
$DCs = Get-ADDomainController -Filter *
$ADUsers = foreach ($OU in $OUs) {
foreach ($dc in $DCs.HostName) {
Get-ADUser -SearchBase $OU.DistinguishedName -Filter * -Properties lastLogonTimeStamp -Server $dc |
Select-Object Name,UserPrincipalName,
#{Name = 'LastLogon';Expression = {[DateTime]::FromFileTime($_.lastLogonTimeStamp)}},
#{Name = 'UserCode'; Expression = {([regex]'^([^_]+)_.*').Match($_.UserPrincipalName).Groups[1].Value}}
}
} }
# return the most recent LastLogon date for each user
# (only the users with a code prefix in the UserPrincipalName)
$ADUsers | Where-Object { ![string]::IsNullOrWhiteSpace($_.UserCode) } |
Group-Object UserPrincipalName | ForEach-Object {
[PsCustomObject]#{
Name = $_.Group[0].Name
UserCode = $_.Group[0].UserCode
LastLogon = $_.Group.LastLogon | Sort-Object -Descending | Select-Object -First 1
}
}
## End function
$OUcustom = Read-Host -prompt 'Enter OU here or "Clients" for all'
##Enter the OU here
Get-LastLogon -OUName $OUcustom |
##export csv
Export-Csv -path "C:\temp\UserExport_$((Get-Date).ToString("ddMM_HHmm")).csv" -NoTypeInformation
".csv extracted to C:\temp"
pause

Answer 1

Just add another calculated property to the code you have to get the array of user objects:
$ADUsers = foreach ($OU in $OUs) {
foreach ($dc in $DCs.HostName) {
Get-ADUser -SearchBase $OU.DistinguishedName -Filter * -Properties lastLogonTimeStamp -Server $dc |
Select-Object Name,UserPrincipalName,
#{Name = 'LastLogon';Expression = {[DateTime]::FromFileTime($_.lastLogonTimeStamp)}},
#{Name = 'UserCode'; Expression = {if ($_.UserPrincipalName -like '*_*#*') {($_.UserPrincipalName -split '_')[0]} else { $null }}}
# or use regex like:
# #{Name = 'UserCode'; Expression = {([regex]'^([^_]+)_.*').Match($_.UserPrincipalName).Groups[1].Value}}
}
}
Then you can filter out the users that do have such a code:
# return the most recent LastLogon date for each user
# (only the users with a code prefix in the UserPrincipalName)
$ADUsers | Where-Object { ![string]::IsNullOrWhiteSpace($_.UserCode) } |
Group-Object UserPrincipalName | ForEach-Object {
[PsCustomObject]#{
Name = $_.Group[0].Name
UserCode = $_.Group[0].UserCode
LastLogon = $_.Group.LastLogon | Sort-Object -Descending | Select-Object -First 1
}
}
If you want to rule out all users that do not have some code followed by an underscore in their UserPrincipalName property straight away, you can use the filter parameter:
Get-ADUser -SearchBase $OU.DistinguishedName -Filter "UserPrincipalName -like '*_*#*'" -Properties lastLogonTimeStamp -Server $dc
This however will not give you the opportunity to use the collected users for some other purpose, like outputting users who do not have a code prefixed, as would be easy to do with the code above.
P.S. Did you know PowerShell also provides an attribute LastLogonDate, which is the LDAP property lastLogonTimeStamp, converted to local time.

Answer 2

So this was actually more simple than I realised.
I just needed to add in:
#{N='userPrincipalName';E={$_.userPrincipalName.Split("_")[0]}}
To the first and second blocks where UserPrincipleName was being selected.
Will post the full working code below for relevance.
##Check bottom of script for setting specific OU
Function Get-LastLogon {
param(
[string]$OUName
)
# Get all matching OUs on any level
$OUs = Get-ADOrganizationalUnit -Filter "Name -like '$OUName'"
$DCs = Get-ADDomainController -Filter *
# Get all users from each OU from each DC
$ADUsers = Foreach ($OU in $OUs) {
Foreach ($DC in $DCs.HostName) {
Get-ADUser -SearchBase $OU.DistinguishedName -Filter * -Properties LastLogon -server $dc |
Select-Object Name,#{N='userPrincipalName';E={$_.userPrincipalName.Split("_")[0]}}, #{n='LastLogon';e={[DateTime]::FromFileTime($_.LastLogon)}}
}
}
# return most recent LastLogon date for each user
$ADUsers |
Group Name,userPrincipalName |
Select Name,#{N='userprinciplename';E={$_.userprinciplename.Split("_")[0]}}, #{n='LastLogon';e={$_.Group.LastLogon | sort -desc | select -First 1}}
} ## End function
$OUcustom = Read-Host -prompt 'Enter OU here or "Clients" for all'
##Enter the OU here
Get-LastLogon -OUName $OUcustom |
##export csv
Export-Csv -path "C:\temp\UserExport_$((Get-Date).ToString("ddMM_HHmm")).csv" -NoTypeInformation
".csv extracted to C:\temp"
pause