fix(core): use cwd for locating workspace root

Closes nrwl#3484
Closes nrwl#3909

packages/cli/bin/nx.ts

@@ -3,14 +3,45 @@
 // polyfill rxjs observable to avoid issues with multiple version fo Observable installed in node_modules
 // https://twitter.com/BenLesh/status/1192478226385428483?s=20
 (Symbol as any).observable = Symbol('observable polyfill');
+import chalk from 'chalk';
 import { findWorkspaceRoot } from '../lib/find-workspace-root';
-import { initGlobal } from '../lib/init-global';
 import { initLocal } from '../lib/init-local';
+import { output } from '../lib/output';
 
-const workspace = findWorkspaceRoot(__dirname);
+const workspace = findWorkspaceRoot(process.cwd());
 
-if (workspace) {
+if (!workspace) {
+  output.log({
+    title: `The current directory isn't part of an Nx workspace.`,
+    bodyLines: [
+      `To create a workspace run:`,
+      chalk.bold.white(`npx create-nx-workspace@latest <workspace name>`),
+    ],
+  });
+
+  output.note({
+    title: `For more information please visit https://nx.dev/`,
+  });
+  process.exit(1);
+}
+
+// Make sure that a local copy of Nx exists in workspace
+let localNx: string;
+try {
+  localNx = require.resolve('@nrwl/cli/bin/nx.js', {
+    paths: [workspace.dir],
+  });
+} catch (e) {
+  output.error({
+    title: `Could not find Nx modules in this workspace.`,
+    bodyLines: [`Have you run ${chalk.bold.white(`npm/yarn install`)}?`],
+  });
+  process.exit(1);
+}
+
+if (localNx === require.resolve('@nrwl/cli/bin/nx.js')) {
   initLocal(workspace);
 } else {
-  initGlobal();
+  // Nx is being run from globally installed CLI - hand off to the local
+  require(localNx);
 }