diff --git a/.eslintignore b/.eslintignore
index 1578d9434..ff8f54135 100644
--- a/.eslintignore
+++ b/.eslintignore
@@ -79,6 +79,8 @@ packages/app-cli/app/LinkSelector.js
 packages/app-cli/app/base-command.js
 packages/app-cli/app/command-done.test.js
 packages/app-cli/app/command-e2ee.js
+packages/app-cli/app/command-mkbook.js
+packages/app-cli/app/command-mkbook.test.js
 packages/app-cli/app/command-settingschema.js
 packages/app-cli/app/command-sync.js
 packages/app-cli/app/command-testing.js
diff --git a/.gitignore b/.gitignore
index 1bd166dd5..3b71c84b4 100644
--- a/.gitignore
+++ b/.gitignore
@@ -67,6 +67,8 @@ packages/app-cli/app/LinkSelector.js
 packages/app-cli/app/base-command.js
 packages/app-cli/app/command-done.test.js
 packages/app-cli/app/command-e2ee.js
+packages/app-cli/app/command-mkbook.js
+packages/app-cli/app/command-mkbook.test.js
 packages/app-cli/app/command-settingschema.js
 packages/app-cli/app/command-sync.js
 packages/app-cli/app/command-testing.js
diff --git a/packages/app-cli/app/base-command.js b/packages/app-cli/app/base-command.js
deleted file mode 100644
index 682ae33a9..000000000
--- a/packages/app-cli/app/base-command.js
+++ /dev/null
@@ -1,97 +0,0 @@
-"use strict";
-var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
-    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
-    return new (P || (P = Promise))(function (resolve, reject) {
-        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
-        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
-        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
-        step((generator = generator.apply(thisArg, _arguments || [])).next());
-    });
-};
-Object.defineProperty(exports, "__esModule", { value: true });
-const locale_1 = require("@joplin/lib/locale");
-const registry_js_1 = require("@joplin/lib/registry.js");
-class BaseCommand {
-    constructor() {
-        this.stdout_ = null;
-        this.prompt_ = null;
-    }
-    usage() {
-        throw new Error('Usage not defined');
-    }
-    encryptionCheck(item) {
-        if (item && item.encryption_applied)
-            throw new Error((0, locale_1._)('Cannot change encrypted item'));
-    }
-    description() {
-        throw new Error('Description not defined');
-    }
-    action(_args) {
-        return __awaiter(this, void 0, void 0, function* () {
-            throw new Error('Action not defined');
-        });
-    }
-    compatibleUis() {
-        return ['cli', 'gui'];
-    }
-    supportsUi(ui) {
-        return this.compatibleUis().indexOf(ui) >= 0;
-    }
-    options() {
-        return [];
-    }
-    hidden() {
-        return false;
-    }
-    enabled() {
-        return true;
-    }
-    cancellable() {
-        return false;
-    }
-    cancel() {
-        return __awaiter(this, void 0, void 0, function* () { });
-    }
-    name() {
-        const r = this.usage().split(' ');
-        return r[0];
-    }
-    setDispatcher(fn) {
-        this.dispatcher_ = fn;
-    }
-    dispatch(action) {
-        if (!this.dispatcher_)
-            throw new Error('Dispatcher not defined');
-        return this.dispatcher_(action);
-    }
-    setStdout(fn) {
-        this.stdout_ = fn;
-    }
-    stdout(text) {
-        if (this.stdout_)
-            this.stdout_(text);
-    }
-    setPrompt(fn) {
-        this.prompt_ = fn;
-    }
-    prompt(message, options = null) {
-        return __awaiter(this, void 0, void 0, function* () {
-            if (!this.prompt_)
-                throw new Error('Prompt is undefined');
-            return yield this.prompt_(message, options);
-        });
-    }
-    metadata() {
-        return {
-            name: this.name(),
-            usage: this.usage(),
-            options: this.options(),
-            hidden: this.hidden(),
-        };
-    }
-    logger() {
-        return registry_js_1.reg.logger();
-    }
-}
-exports.default = BaseCommand;
-//# sourceMappingURL=base-command.js.map
\ No newline at end of file
diff --git a/packages/app-cli/app/command-mkbook.js b/packages/app-cli/app/command-mkbook.js
deleted file mode 100644
index 9dbdaff01..000000000
--- a/packages/app-cli/app/command-mkbook.js
+++ /dev/null
@@ -1,21 +0,0 @@
-const BaseCommand = require('./base-command').default;
-const { app } = require('./app.js');
-const { _ } = require('@joplin/lib/locale');
-const Folder = require('@joplin/lib/models/Folder').default;
-
-class Command extends BaseCommand {
-	usage() {
-		return 'mkbook <new-notebook>';
-	}
-
-	description() {
-		return _('Creates a new notebook.');
-	}
-
-	async action(args) {
-		const folder = await Folder.save({ title: args['new-notebook'] }, { userSideValidation: true });
-		app().switchCurrentFolder(folder);
-	}
-}
-
-module.exports = Command;
diff --git a/packages/app-cli/app/command-mkbook.test.ts b/packages/app-cli/app/command-mkbook.test.ts
new file mode 100644
index 000000000..6e7e1de19
--- /dev/null
+++ b/packages/app-cli/app/command-mkbook.test.ts
@@ -0,0 +1,50 @@
+import { setupDatabaseAndSynchronizer, switchClient } from '@joplin/lib/testing/test-utils';
+import { setupCommandForTesting, setupApplication } from './utils/testUtils';
+import Folder from '@joplin/lib/models/Folder';
+const Command = require('./command-mkbook');
+
+
+describe('command-mkbook', () => {
+
+	beforeEach(async () => {
+		await setupDatabaseAndSynchronizer(1);
+		await switchClient(1);
+		await setupApplication();
+	});
+
+
+	it('should create a subfolder in first folder', async () => {
+		const command = setupCommandForTesting(Command);
+		await command.action({ 'new-notebook': 'folder1', options: {} });
+		await command.action({ 'new-notebook': 'folder1_1', options: { parent: 'folder1' } });
+
+		const folder1 = await Folder.loadByTitle('folder1');
+		const folder1_1 = await Folder.loadByTitle('folder1_1');
+
+		expect(folder1.title).toBe('folder1');
+		expect(folder1_1.parent_id).toBe(folder1.id);
+	});
+
+	it('should not be possible to create a subfolder without an argument.', async () => {
+		const command = setupCommandForTesting(Command);
+		await command.action({ 'new-notebook': 'folder2', options: {} });
+		await expect(command.action({ 'new-notebook': 'folder2_1', options: { parent: true } })).rejects.toThrowError();
+	});
+
+	it('should not be possible to create subfolder in ambiguous destination folder', async () => {
+		const command = setupCommandForTesting(Command);
+		await command.action({ 'new-notebook': 'folder3', options: {} });
+		await command.action({ 'new-notebook': 'folder3', options: {} });	// ambiguous folder
+		await expect(command.action({ 'new-notebook': 'folder3_1', options: { parent: 'folder3' } })).rejects.toThrowError();
+
+		// check if duplicate entries have been created.
+		const folderAll = await Folder.all();
+		const folders3 = folderAll.filter(x => x.title === 'folder3');
+		expect(folders3.length).toBe(2);
+
+		// check if something has been created in one of the duplicate entries.
+		expect(await Folder.childrenIds(folders3[0].id)).toEqual([]);
+		expect(await Folder.childrenIds(folders3[1].id)).toEqual([]);
+	});
+});
+
diff --git a/packages/app-cli/app/command-mkbook.ts b/packages/app-cli/app/command-mkbook.ts
new file mode 100644
index 000000000..9677f446d
--- /dev/null
+++ b/packages/app-cli/app/command-mkbook.ts
@@ -0,0 +1,65 @@
+const BaseCommand = require('./base-command').default;
+const { app } = require('./app.js');
+import { _ } from '@joplin/lib/locale';
+import BaseModel from '@joplin/lib/BaseModel';
+import Folder from '@joplin/lib/models/Folder';
+import { FolderEntity } from '@joplin/lib/services/database/types';
+
+class Command extends BaseCommand {
+	usage() {
+		return 'mkbook <new-notebook>';
+	}
+
+	description() {
+		return _('Creates a new notebook.');
+	}
+
+	options() {
+		return [
+			['-p, --parent <parent-notebook>', _('Create a new notebook under a parent notebook.')],
+		];
+	}
+
+	// validDestinationFolder check for presents and ambiguous folders
+	async validDestinationFolder(targetFolder: string) {
+
+		const destinationFolder = await app().loadItem(BaseModel.TYPE_FOLDER, targetFolder);
+		if (!destinationFolder) {
+			throw new Error(_('Cannot find: "%s"', targetFolder));
+		}
+
+		const destinationDups = await Folder.search({ titlePattern: targetFolder, limit: 2 });
+		if (destinationDups.length > 1) {
+			throw new Error(_('Ambiguous notebook "%s". Please use short notebook id instead - press "ti" to see the short notebook id', targetFolder));
+		}
+
+		return destinationFolder;
+	}
+
+	async saveAndSwitchFolder(newFolder: FolderEntity) {
+
+		const folder = await Folder.save(newFolder, { userSideValidation: true });
+		app().switchCurrentFolder(folder);
+
+	}
+
+	async action(args: any) {
+		const targetFolder = args.options.parent;
+
+		const newFolder: FolderEntity = {
+			title: args['new-notebook'],
+		};
+
+		if (targetFolder) {
+
+			const destinationFolder = await this.validDestinationFolder(targetFolder);
+			newFolder.parent_id = destinationFolder.id;
+			await this.saveAndSwitchFolder(newFolder);
+
+		} else {
+			await this.saveAndSwitchFolder(newFolder);
+		}
+	}
+}
+
+module.exports = Command;