Variables in Start-Job do not get evaluated - powershell

Question

My Powershell code doesn't evaluate the $agent variable:
foreach ($agent in $agentcomputers) {
Write-Output 'Starting agent on '$agent
# psexc to start the agent
Start-Job -ScriptBlock {& psexec $agent c:\grinder\examples\startAgent.cmd}
}
This link is similar to my problem, except I'm not calling an external Powershell script.
I tried adding that in, using $args[0] for $agent, and adding the -ArgumentList parameters, but that didn't work.
Edits/Replies
$agentcomputers is just a list of computer names - each on its own line:
$agentcomputers = Get-Content c:\grinder-dist\agent-computers.txt
I have also tried this - and $args[0] doesn't evaluate:
Start-Job -ScriptBlock {& psexec $args[0] c:\grinder\examples\startAgent.cmd} -ArgumentList #($agent)

Answer 1

Here are 3 different ways I would do it.
First, all aligned and pretty.
$agents = Get-Content c:\grinder-dist\agent-computers.txt
$jobs = {
Param($agent)
write-host "Starting agent on" $agent
& psexec \\$agent c:\grinder\examples\startAgent.cmd
}
foreach($agent in $agents) {
Start-Job -ScriptBlock $jobs -argumentlist $agent | Out-Null
}
Get-Job | Wait-Job | Receive-Job
Or you could just put it all on one line without creating any variables.
(Get-Content c:\grinder-dist\agent-computers.txt) | %{ Start-Job -ScriptBlock { param($_) write-host "Starting agent on" $_; & psexec \\$_ c:\grinder\examples\startAgent.cmd } -argumentlist $_ | Out-Null }
Get-Job | Wait-Job | Receive-Job
And in this final example, you could manage how many threads are run concurrently by doing it this way.
$MaxThreads = 5
$agents = Get-Content c:\grinder-dist\agent-computers.txt
$jobs = {
Param($agent)
write-host "Starting agent on" $agent
& psexec \\$agent c:\grinder\examples\startAgent.cmd
}
foreach($agent in $agents) {
Start-Job -ScriptBlock $jobs -argumentlist $agent | Out-Null
While($(Get-Job -State 'Running').Count -ge $MaxThreads) {
sleep 10
}
Get-Job | Wait-Job | Receive-Job
}

Answer 2

Here is the solution. As Andy said, I needed to use $args array with the -ArgumentList parameter. This other thread was helpful: Powershell: passing parameters to a job
foreach($agent in $agentcomputers){
$agentslash = "\\"+$agent
$args = ($agentslash,"c:\grinder\examples\startAgent.cmd")
Write-Output 'Starting agent on '$agent
#psexc to start the agent
$ScriptBlock = {& 'psexec' #args }
Start-Job -ScriptBlock $ScriptBlock -ArgumentList $args
}