Pipe to Powershell

Pipe commands to a powershell instance and get results as JSON

Installation

npm i pipe-to-powershell

FNs

createPowershellStream(returnCallback|null, config? = CONFIG_DEFAULT): pipeControl

Initializes (spawns) the powershell.

returnCallback = ( pipeResults: {data: JSON|null, errors: string[]|null} ): void

• If you do not want to use returnCallback (like only using get()), you may deliberately pass null.

pipeControl = {close, exec, get} ... see below

CONFIG_DEFAULT =

{
	bin: string = 'pwsh' /*executable binary*/, 
	stream: stream.Stream|null = stream.Readable /*input stream*/, 
	execMode: 'brackets'|null = 'brackets' /*see notes*/
}

• In case powershell changes its prompts, additional config properties {delim = 'PS ', delimMultiline = '>> '} can be overwritten.

• You might want to use get() and change to an older powershell:

  let {close, get} = createPowershellStream(null, {bin: 'powershell.exe'});

close(): void

Closes the pipes and Kills the spawned powershell.

exec(cmdStr: String): void

Trigger a command an let the resultCallback handle it. Fire and forget.

get(cmdStr: String): Promise<pipeResults>

Trigger a command and waits for its result, temporarely rerouting the resultCallback.

Should be awaited to mitigate race conditions. Running in paralell is not supported due to the nature of piping and rerouting the resultCallback.

Does not need returnCallback, during initialisation the param can be set to null. You should be using close(), when you are done.

// get result and all errors produced
let {data, error} = await get('ls');

// this will decunstruct pipeResults, extracting data, and provide it as variable 'files'
let {data: files} = await get('ls');

pushing to the input pipe

You can always use inputStream.push(string), but note, your command should end with \n

Debugging

Environment Parameter

DEBUG_PIPETOPOWERSHELL=true

Within code:

process.env.DEBUG_PIPETOPOWERSHELL = true;

Notes

• Variable expressions should always be in brackets, which is automatically done by config.execMode: ($a = "Hello") - because the conversion to JSON for the result would save the JSON encoded version (with extra quotes).

Examples

Terminal input to powershell, try: npm start

import createPowershellStream from 'pipe-to-powershell';


process.stdout.write('press ^D to end \n:: ');

// create a piped commandline with custom prompt 
let {close, call, get} = createPowershellStream(({data, errors}) => {
	// show powershell result
	console.log('ERRORS:', errors, 'DATA:', data);

	// show a custom promt for next input
	process.stdout.write(':: ');
}, {stream: process.stdin}); // process.stdin or null (null == string pipe)

Trigger a few commands on powershell and get results, while piping to the same instance, try npm test

import createPowershellStream from 'pipe-to-powershell';


// create a piped commandline with custom prompt - no callback needed
let {close, get} = createPowershellStream(null);

(async _ => {

	let {data: files} = await get('ls');

	console.log('Files in this folder: ', files.length);

	let {data: ver} = await get('$PSVersionTable.PSVersion');

	console.log(`PS Version: ${ver.Major}.${ver.Minor}.${ver.Patch}`);

	close();
})();

Consecutive manipulates to the powershell environment: changing variables and relying on the previous changes, try npm run test3

import createPowershellStream from 'pipe-to-powershell';


// create a piped commandline with custom prompt - no callback needed
let {close, get} = createPowershellStream(null);

// we will NOT use exec(), since it would not wait

(async _ => {

	await get(`$a = "Hello"`);

	let ret = await get('$a');

	console.log('Value: ', ret.data);

	await get(`$a = "$($a) World!"`);

	ret = await get('$a');

	console.log('Value: ', ret.data);

	close();
})();