Learning PowerShell. Create usernames no longer than 8 characters and check for collision - powershell

Question

I'm learning powershell right now.
I need to import a CSV like this:
lastname,firstname
lastname,firstname
lastname,firstname
etc
Then create a list of usernames no longer then 8 characters and check for collisions.
I have found bits and pieces of scripting around but not sure how to tie it all together.
I use Import-Csv to import my file.csv:
$variablename = import-csv C:\path\to\file.csv
but then I am not sure if I just import it into an array or not. I am not familiar with how for loops work in powershell exactly.
Any direction? Thanks.

Answer 1

There are a couple of concepts that are central to understanding PowerShell. Firstly, remember that you are always working with objects. So after importing your CSV file, your $variablename will refer to a collection of sub-objects.
Secondly, you can use the PowerShell pipeline to send the output of one cmdlet to the input of another. Some cmdlets will understand if you send them a collection, and automatically process each row.
If think what you're looking for though is the foreach-object cmdlet, which will allow you to run code against each item in the collection. Code inside the foreach-object block can refer to the $_ automatic variable which will contain the current object.
Assuming your CSV file is well formatted and has a header row with the column names, you can refer to each column by name e.g. $_.lastname & $_.firstname.
To put it all together:
import-csv C:\path\to\file.csv |
foreach-object {
write-host "Processing: $($_.lastname), $($_.firstname)"
# logic here to calculate username and create AD account
}
PowerShell can have a bit of a learning curve if you are coming from a different scripting environment. Here are a couple of resources that I've found helpful:
PowerShell 'gotchas' http://www.rlmueller.net/PSGotchas.htm
Keith Hill's Effective PowerShell: https://rkeithhill.wordpress.com/2009/03/08/effective-windows-powershell-the-free-ebook/
Also, check out the Technet Script Center, where there are many hundreds of Active Directory scripts. https://technet.microsoft.com/en-us/scriptcenter/bb410849.aspx

Answer 2

The script below should help you grasp a few concepts on how to work with csvs and manipulate data using PowerShell.
# the code below uses a 'here string' to mimic the import of a csv.
$users = #'
smith,b
smith,bob
smith,bobby
smith,sonny
smithson,john
smithson,jane
smithers,rob
'# -split "`r*`n"
$users |
ConvertFrom-Csv -Header 'surname','firstname' |
Select-Object #{Name='username'; Expression={"$($_.surname)$($_.firstname) "}}, surname, firstname |
Group-Object { $_.username.Substring(0,8).Trim() } |
Select-Object #{Name='username'; Expression={$_.Name}}, Count |
Format-Table -AutoSize
The $users | line takes the list of $users and pipes into the next command.
The ConvertFrom-Csv -Header... line converts the string into a csv.
The Select-Object #{Name... line creates an expression alias, which concatenates surname+forename. You'll notice the extra 8 spaces we append to the end of the string so we know we will have at least 8 characters in the string.
The Group-Object {... line groups the username, using the first 8 characters, if available. The .Trim() gets rid of any trailing spaces.
The Select-Object #{Name='username'... line takes the Name field from the group-object and renames to username and also shows the count from the grouping operation.
The Format-Table -AutoSize line is purely for output formatting to the console and gives you an output like the one below.
username Count
-------- -----
smithb 1
smithbob 2
smithson 3
smithers 1
An amended version of the above code, which you can use on your real csv. Change the surname, firstname column names to suit your csv.
# you would use the code below, to import your list of names
# uncomment the `# -Header surname,firstname` bit if your csv has no headers
$users = Import-Csv -Path 'c:\path\to\names.csv' # -Header surname,firstname
$users |
Select-Object #{Name='username'; Expression={"$($_.surname)$($_.firstname) "}}, surname, firstname |
Group-Object { $_.username.Substring(0,8).Trim() } |
Select-Object #{Name='username'; Expression={$_.Name}}, Count