CODEWITHSUNDEEP
powershellcygwin
iank
iank

Reputation: 810

Powershell's Read-Host cmdlet causes hanging when script is ran from Cygwin

I'm trying to run a powershell script from within Cygwin (ultimately will be run over Cygwin SSH), and am finding that user input seems to be ignored. The script displays a menu and then uses Read-Host "Your selection:" to receive the input.

There is a blinking cursor, but the "Your selection" text doesn't appear, and anything I enter seems to just write to the console itself and is ignored by the script.

Does anyone know what could be wrong?

Thanks very much.

Upvotes: 2

Views: 641

Answers (1)

Χpẘ
Χpẘ

Reputation: 3451

I'm guessing Cygwin console does not implement the APIs that the Powershell console's host (System.Management.Automation.Internal.Host.InternalHostUserInterface) depends on. Or doesn't implement them as expected. This will surely be the case if you attempt to run over SSH. MS has documentation on how to write a custom Host UI. So if you want to run PS over SSH seems like there are 4 possibilities:

  1. Write your own PSHost implementation
  2. Find someone else's PSHost implementation
  3. Use your SSH's clients stdin and stdout as a two way pipe and write a REPL that takes input from the pipe (SSH stdin) and sends output to the pipe (SSH stdout). Unless you implement it yourself, this option means you lose line editing, history, tab completion, etc.
  4. Not sure if this one will work, but it would might be the least amount of code to implement if it does. Create a child PS process. Redirect the child's stdout, stdin to the parent PS process. All input you get from SSH stdin you write to child PS's stdin and all output you read from child's stdout you write to SSH stdout. You'll probably want to use asynchronous I/O for the reads on SSH stdin and child's stdout, to prevent hangs (if script is waiting on a read from child's stdout, but the child PS has no more output, then the script is hung). In effect the SSH user is controlling the child PS process and the parent PS process is just the glue joining the two together.

Upvotes: 1

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