diff --git a/composables/umask.ts b/composables/umask.ts
new file mode 100644
index 0000000..d9d2f73
--- /dev/null
+++ b/composables/umask.ts
@@ -0,0 +1,18 @@
+import { createGlobalState } from '@vueuse/core';
+
+export const useUmaskStore = createGlobalState(() => {
+  const umask = ref(window?.localStorage?.getItem('umask') || '000000000010');
+  function changeUmask(newUmask: string & { length: 12 } & { [index: number]: '0' | '1' }) {
+    umask.value = newUmask;
+    localStorage.setItem('umask', newUmask);
+  }
+  function clearUmask() {
+    umask.value = '000000000010';
+    localStorage.setItem('umask', umask.value);
+  }
+  return {
+    umask,
+    changeUmask,
+    clearUmask,
+  };
+});
diff --git a/composables/user.ts b/composables/user.ts
index 15eb397..c8de507 100644
--- a/composables/user.ts
+++ b/composables/user.ts
@@ -1,6 +1,7 @@
 import { createGlobalState } from '@vueuse/core';
 
 export const useUserStore = createGlobalState(() => {
+  const { clearUmask } = useUmaskStore();
   const username = ref(window?.localStorage?.getItem('username') || 'guest');
   onMounted(async () => {
     if (username.value === 'guest') {
@@ -19,6 +20,7 @@ export const useUserStore = createGlobalState(() => {
   function switchUser(name: string) {
     username.value = name;
     localStorage.setItem('username', name);
+    clearUmask();
   }
   watch(username, async () => {
     const meta = (await useFetch('/api/users', {
diff --git a/lib/command/impls/help.ts b/lib/command/impls/help.ts
index e3c7e81..a25a8cc 100644
--- a/lib/command/impls/help.ts
+++ b/lib/command/impls/help.ts
@@ -45,6 +45,12 @@ const commandDescriptions: Record<Command, CommandDescription> = {
       { args: ['-u <username>', '-p <password>'] },
     ],
   },
+  [Command.UMASK]: {
+    description: 'Set file mode creation mask',
+    usages: [
+      { args: ['(<oct><oct><oct>)?'] },
+    ],
+  },
 };
 
 function getDescription(commandName: string): string[] {
diff --git a/lib/command/impls/mkdir.ts b/lib/command/impls/mkdir.ts
new file mode 100644
index 0000000..50469a5
--- /dev/null
+++ b/lib/command/impls/mkdir.ts
@@ -0,0 +1,12 @@
+import { formatArg } from '../utils';
+import type { CommandFunc } from './types';
+
+export const mkdir: CommandFunc = async function(...args) {
+  // discard `mkdir`
+  args.shift();
+  // discard first space
+  args.shift();
+
+  return [
+  ];
+};
diff --git a/lib/command/impls/touch.ts b/lib/command/impls/touch.ts
new file mode 100644
index 0000000..994625c
--- /dev/null
+++ b/lib/command/impls/touch.ts
@@ -0,0 +1,12 @@
+import { formatArg } from '../utils';
+import type { CommandFunc } from './types';
+
+export const touch: CommandFunc = async function(...args) {
+  // discard `touch`
+  args.shift();
+  // discard first space
+  args.shift();
+
+  return [
+  ];
+};
diff --git a/lib/command/impls/types.ts b/lib/command/impls/types.ts
index 096b1af..7a710db 100644
--- a/lib/command/impls/types.ts
+++ b/lib/command/impls/types.ts
@@ -7,4 +7,7 @@ export enum Command {
   SU = 'su',
   LS = 'ls',
   USERADD = 'useradd',
+  TOUCH = 'touch',
+  MKDIR = 'mkdir',
+  UMASK = 'umask',
 }
diff --git a/lib/command/impls/umask.ts b/lib/command/impls/umask.ts
new file mode 100644
index 0000000..28b4242
--- /dev/null
+++ b/lib/command/impls/umask.ts
@@ -0,0 +1,58 @@
+import { formatArg } from '../utils';
+import type { CommandFunc } from './types';
+
+export const umask: CommandFunc = async function(...args) {
+  // discard `umask`
+  args.shift();
+  // discard first space
+  args.shift();
+
+  if (args.length === 0) {
+    const { umask } = useUmaskStore();
+    return [umaskToOct(umask.value)];
+  }
+
+  if (args.length > 1) {
+    return [
+      'Invalid use of umask. Run \'help umask\'',
+    ];
+  }
+
+  const umask = formatArg(args[0]);
+  if (umask.length !== 3 || !isOctDigit(umask[0]) || !isOctDigit(umask[1]) || !isOctDigit(umask[2])) {
+    return ['Invalid umask'];
+  }
+  const { changeUmask } = useUmaskStore();
+  changeUmask(umaskFromOct(umask as any));
+  return [
+    'Change umask successfully',
+  ];
+};
+
+function isOctDigit(c: string): boolean {
+  const n = Number.parseInt(c);
+  return c.length === 1 && 0 <= n && n <= 7;
+}
+
+function umaskToOct(umask: string): string {
+  const ownerRead = Number.parseInt(umask[3]);
+  const ownerWrite = Number.parseInt(umask[4]);
+  const ownerExecute = Number.parseInt(umask[5]);
+  const ownerOct = ownerRead * 4 + ownerWrite * 2 + ownerExecute;
+  const groupRead = Number.parseInt(umask[6]);
+  const groupWrite = Number.parseInt(umask[7]);
+  const groupExecute = Number.parseInt(umask[8]);
+  const groupOct = groupRead * 4 + groupWrite * 2 + groupExecute;
+  const otherRead = Number.parseInt(umask[9]);
+  const otherWrite = Number.parseInt(umask[10]);
+  const otherExecute = Number.parseInt(umask[11]);
+  const otherOct = otherRead * 4 + otherWrite * 2 + otherExecute;
+  return `${ownerOct}${groupOct}${otherOct}`;
+}
+
+function umaskFromOct(octs: string): string {
+  const ownerOct = octs[0];
+  const groupOct = octs[1];
+  const otherOct = octs[2];
+  return `000${ownerOct.toString(2).padStart(3, '0')}${groupOct.toString(2).padStart(3, '0')}${otherOct.toString(2).padStart(3, '0')}`;
+}
diff --git a/lib/command/index.ts b/lib/command/index.ts
index 3c19ea9..50c5fcb 100644
--- a/lib/command/index.ts
+++ b/lib/command/index.ts
@@ -8,6 +8,9 @@ import { cd } from './impls/cd';
 import { su } from './impls/su';
 import { ls } from './impls/ls';
 import { useradd } from './impls/useradd';
+import { touch } from './impls/touch';
+import { mkdir } from './impls/mkdir';
+import { umask } from './impls/umask';
 
 export async function execute(command: string): Promise<ColoredContent> {
   const args = parse(command);
@@ -37,6 +40,15 @@ export async function execute(command: string): Promise<ColoredContent> {
   case Command.USERADD:
     res = await useradd(...args as any);
     break;
+  case Command.TOUCH:
+    res = await touch(...args as any);
+    break;
+  case Command.MKDIR:
+    res = await mkdir(...args as any);
+    break;
+  case Command.UMASK:
+    res = await umask(...args as any);
+    break;
   default:
     res = echo('echo', ' ', `Unknown command:\\u001b[31m ${args[0]}`);
     break;
diff --git a/services/files.ts b/services/files.ts
index 0716744..25fb861 100644
--- a/services/files.ts
+++ b/services/files.ts
@@ -69,6 +69,8 @@ export const fileService = {
   },
   async createFile(filename: string): Promise<Result<null, Diagnostic>> {
   },
+  async createFolder(filename: string): Promise<Result<null, Diagnostic>> {
+  },
   async changeDirectory(filename: string): Promise<Result<null, Diagnostic>> {
     try {
       const { cwd, switchCwd } = useCwdStore();