Get var from powershell in C#

Question

I run a command in Powershell from C#, and I need to read the content of a var. I tried all the solutions I found online but none worked so far.

Here is my current code (with some "attempts" still included)

string output;

var nodePath = HttpContext.Server.MapPath("~/.bin/node.exe");
var mjmlFromStringCmd = HttpContext.Server.MapPath("~/.bin/mjmlFromString");
var mjmlTemplate = System.IO.File.ReadAllText(HttpContext.Server.MapPath("~/.bin/test.mjml"));
var command = $"$htmlOutput = {nodePath} {mjmlFromStringCmd} -c '{mjmlTemplate}'";

var powershell = PowerShell.Create();
powershell.Commands.AddScript(command);
var t = powershell.Invoke(); // I tired using powershell.Invoke()[0] because a post on SO said it might work, but the array returned by Invoke contains 0 elements
var bf = powershell.Runspace.SessionStateProxy.PSVariable.Get("htmlOutput"); // I tried to get the var using two different methods, both give an empty value
var htmlOutput = powershell.Runspace.SessionStateProxy.GetVariable("htmlOutput");
output = htmlOutput as string;

and here is the executed powershell command

$htmlOutput = C:\\Perso\\Websites\\FoyerRural\\.bin\\node.exe C:\\Perso\\Websites\\FoyerRural\\.bin\\mjmlFromString -c '****lots of content - MJML template (xml-style markup)****'

If I run the command directly in a powershell prompt, the $htmlOutput var gets its value and I can print it by calling

$htmlOutput

Is there some trick with the C# powershell class that I missed ? How can I get the value of the powershell htmlOutput variable in C# ?

How would you do that ? I looked it up but i couldn't find much info about it ... I tried my var's initialization to `$global:htmlOutput`, but it didn't change anything. I tried fetching the var like i did before, and i also tried adding `global:` before the var name in the call to `GetVariable` ... still get a null value :-/ — Mathieu VIALES, Sep 26 '17 at 13:28
Reading/writing environment variables is straightforward in both powershell and C#. See https://ss64.com/ps/syntax-env.html. — Paul Suart, Sep 26 '17 at 13:33

score 3 · Accepted Answer · answered Sep 26 '17 at 14:57

Thank you all for your help, you put me on the right tracks. Here is the final working code

var nodePath = HttpContext.Server.MapPath("~/.bin/node.exe");
var mjmlFromStringCmd = HttpContext.Server.MapPath("~/.bin/mjmlFromString");
var mjmlTemplate = System.IO.File.ReadAllText(HttpContext.Server.MapPath("~/.bin/test.mjml"));
var command = $"$htmlOutput = {nodePath} {mjmlFromStringCmd} -c '{mjmlTemplate}'";

var powerShell = PowerShell.Create();

powerShell.AddScript(command);
powerShell.Invoke();
// GetVariable returns an "object", that is in fact an array of PSObjec
var lines = ((object[]) powerShell.Runspace.SessionStateProxy.GetVariable("htmlOutput")).Cast<PSObject>();
// Agregate all returned PSObjec (each one of them being a line from the powershell output) and aggregate them into a string
output = t.Aggregate(output, (current, item) => current + item.BaseObject.ToString());

Took a lot of brain-twisting but it does work.

score 1 · Answer 2 · answered Sep 26 '17 at 13:15

1

I've never done this before but seems like you are not the only one who has this question, check out the answers over at :

How to get value from powershell script into C# variable?

passing powershell variables to C# code within PS script

answered Sep 26 '17 at 13:15

Snak3d0c

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When using [this](https://stackoverflow.com/a/44477456/6838730) method, i get a ps.Invoke() returning an empty list. The other one just won't work (i'm trying to debug it) – Mathieu VIALES Sep 26 '17 at 13:22
So i tried both, i get a list containing 0 result in both cases :-/ – Mathieu VIALES Sep 26 '17 at 13:32
So i have no experience in C# and i can't really test with you but in that code the execution policy is set. That requires Administrative rights. Maybe run your code as an Administrator? Its a long shot – Snak3d0c Sep 26 '17 at 13:35

Get var from powershell in C#

2 Answers2