Author Posts

December 15, 2015 at 3:37 am

Hi,

I'm trying to do something that I don't know if I'm doing the right way.
I'm doing a script to get event logs from a machine, and want to give options to the user.
Example of the command:

Get-EventLog -LogName System | select -First 20

So I want to give the option to show the first X records or show all records.
What I've tried was:


$period = "select | -First 20"
Get-EventLog -LogName System $period

But that doesn't work... and I don't want to make a if statement like:


if ($period -ne $Null){
Get-EventLog -LogName | select -First $period
}
else{
Get-EventLog -LogName
}

December 15, 2015 at 3:46 am

I was able to do what I want using this:


$records = Read-Host "Type the amount of records desired"
$period = "| select -First $records"
$cmd = "Get-EventLog -LogName System $period"
Invoke-Expression $cmd

Still don't know if this is the best way

December 15, 2015 at 5:35 am

That's very dangerous. Whatever the user types gets executed, and they can do some nasty things that way (intentionally or by accident).

You're going to wind up with an If statement somewhere regardless of what you do, if you want the select-object part to be optional. I'd just go with what's in your first post, personally.

December 15, 2015 at 7:52 am

Dave Wyatt,

Thanks!

December 15, 2015 at 9:53 am

Here is a way to do what you want using array partitioning, but I agree with Dave. The 'if" option is better because the select cmdlet will stop the retrieval of the rest of the log file once the requested number of entries has been retrieved. Using this method, the entire event log is retrieved, but only the requested number of entries are displayed.

$eventcount = 5
(Get-EventLog -LogName System)[0..($eventcount - 1)]

December 16, 2015 at 3:46 am

Excusively for EventLog: there is -Newest parameter
Get-EventLog -LogName system | select -first 10
is equivalent of
Get-EventLog -LogName system -Newest 10

and usage of this parameter can be solved with splatting

$params = @{LogName='System'}
if ($wantLimit) {
 $params.Newest = 10
#$params.Newest = $wantLimit
}
Get-EventLog @params