Pass information between independently running Powershell scrips - powershell

Question

Sorry for being wage before. I'll try again:
The circumstances are too complicated to explain, but basically the problem is:
how to pass a string (max 20 chars) from one script, to another script running on the same machine.
the two scripts are running continuously in the background, on the same machine, under the same user context,
but can not be combined.
I can not dot-source one script in the other.
I have done it by having one script create a file with the string in it, in a directory monitored by the other script. So when it appears, the other script reads the information.
It works, but it feels "dirty". :)
I was wondering if there is a "best practice"-way to pass information between scripts or at least a more elegant way.
Thanks.

Answer 1

There are several ways for enabling two continuously running processes on the same host to communicate with each other, for instance named pipes:
# named pipe - server
$name = 'foo'
$namedPipe = New-Object IO.Pipes.NamedPipeServerStream($name, 'Out')
$namedPipe.WaitForConnection()
$script:writer = New-Object IO.StreamWriter($namedPipe)
$writer.AutoFlush = $true
$writer.WriteLine('something')
$writer.Dispose()
$namedPipe.Dispose()
# named pipe - client
$name = 'foo'
$namedPipe = New-Object IO.Pipes.NamedPipeClientStream('.', $name, 'In')
$namedPipe.Connect()
$script:reader = New-Object IO.StreamReader($namedPipe)
$reader.ReadLine()
$reader.Dispose()
$namedPipe.Dispose()
or TCP sockets:
# TCP socket - server
$addr = [ipaddress]'127.0.0.1'
$port = 1234
$endpoint = New-Object Net.IPEndPoint ($addr, $port)
$server = New-Object Net.Sockets.TcpListener $endpoint
$server.Start()
$cn = $server.AcceptTcpClient()
$stream = $cn.GetStream()
$writer = New-Object IO.StreamWriter($stream)
$writer.WriteLine('something')
$writer.Dispose()
$server.Stop()
# TCP socket - client
$server = '127.0.0.1'
$port = 1234
$client = New-Object Net.Sockets.TcpClient
$client.Connect($server, $port)
$stream = $client.GetStream()
$reader = New-Object IO.StreamReader($stream)
$reader.ReadLine()
$reader.Dispose()
$client.Dispose()

Answer 2

The easy solution would be to make the second script a function, then dot source it and just capture the return value into a variable.
I'm not entirely sure if this is possible otherwise, you could try $global:variableName or possibly run something as a job. If none of that works you could make the second script store the result in a file then access that file from the first script.

Answer 3

While your question is not very clear, i'll try to answer it.
It seems like you want to continue processing on your first script while your second script is doing (something).
You can put a specific operation in a Job (sort of like a thread) and receive it later with a while ($true) loop specifying conditions that meet your needs then break out of the loop after receiving the results from that Job, or thread.
Take a look at Get-Help | Start-Job for more info on that, or try to hit up google.
You can also import user-defined functions from another script by doing an import-module '.\pathtoscriptmodule.psm1' or just .\Pathtoscriptdefiningfunctions.ps1 to import functions you want to use from an outside script file.
Examples of using Start job..
$scriptblock = {
param($myParam);
# My commands here
}
Start-Job -ScriptBlock $scriptblock -args $myParamsIWantToPassToScriptblock
While ($true){
# To view status of that background job
Get-Job *
# Add your logic for fulfilling your conditons here, then
# break; <<uncomment to break out of loop
if (conditions met)
{
break;
}
}
# Gets the output from that job. -Keep keeps the output in memory
# if you want to call it multiple times
Receive-Job * -Keep

Answer 4

You could look into using runspaces.
http://learn-powershell.net/2013/04/19/sharing-variables-and-live-objects-between-powershell-runspaces/