PowerShell: Append to an array from a file

Posted on 2010-09-07
Last Modified: 2012-05-10
I have the following code that is used to populated a $ServerList (starting a $ServerList[1]), but I'd also like to be able to read a file of servernames... and append those names to the end of the ServerList string type.

The issue is, that $ServerList is a pre-dementioned array.  That reason for this is because I get the error:

"Cannot index into a null array."

If attempt to run the code below:

# Grab list of servers use QAD then select the name object, and then short the results by the name

$a = (Get-QADComputer -OSName 'Windows*Server*' | Select-Object name | Sort-Object name )
$b = ($a | ForEach-Object {$})

# Create the list of servers array, but start the elements from 1, not zero.

$ServerList = New-Object string[] ($b.Count+2)

for ($j=0; $j -le $b.count; $j++) { $ServerList[$j+1]=$b[$j]}

As yiu can see, there is a whole lot of swapping going on here... primarily because the output of $a gives me headers, and the populating of $b starts at zero (e.g. $b[0]).  Which causes issues with friggen Excel, so we then dump the contents of $b into $ServerList.

So then I take a CSV file, and I want to add it to the $ServerList array, but I get an ERROR... because the array is not dimmensioned to fit to additional strings:

# Load CSV list of additional servers NOT on the Domain and add them to the list of servers

$a = Import-Csv y:\AddititionalServerList.csv
$b = ($a | ForEach-Object {$})

What I'd like to do, is simply append these to the end of the $ServerList array:

$ServerList = $ServerList+$b

But that doesn't work...

Can anyone work this out for me?

Question by:gerhardub
LVL 13

Accepted Solution

soostibi earned 500 total points
ID: 33625674
I do not exactly know, why it does not work for you, as it workes for me.
But anyway, the code is not very nice and efficient.
My suggestion is this (you can change the text "insertion" in the last line to anything):
$serverlist = [collections.arraylist] (@(Get-QADComputer -OSName 'Windows*Server*' | Select-Object -ExpandProperty name), 
    @(import-csv y:\AddititionalServerList.csv | Select-Object -ExpandProperty name) | %{$_} | Sort-Object)

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Author Closing Comment

ID: 33627556

I figure a few hundred more learning experiences like this and I'll actually know what I'm doing.

That's exactly the information I needed to fix this.

Thank YOU!

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