diff --git a/README.md b/README.md
index a7ea02c..09314e2 100644
--- a/README.md
+++ b/README.md
@@ -27,10 +27,6 @@ npx gitarist setup
   - comment on issues
 - Run cron job using `Github Action`
 
-## Contribution
-
-[Contribution guide](./CONTRIBUTING.md)
-
 ## Contributing
 
 1. [Fork it](https://help.github.com/articles/fork-a-repo/)
diff --git a/src/cli.ts b/src/cli.ts
index ca3f707..159778b 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -11,12 +11,15 @@ import {
   StartCommandOptions,
   branchPrefixes,
 } from './github';
+import { CreateEnvExampleOptions, createEnvExample } from './libs';
 
 const program = new Command().name(name).description(description).version(version);
 
 program
   .command('setup')
-  .description('setup')
+  .description(
+    'It sets up gitarist suite. It will create a new GitHub workflow file and `.env` file, adds environment variables to .env file, and opens a browser to create a new GitHub token.',
+  )
   .addOption(new Option('--remote <string>', 'the name of remote').default(DEFAULT.remote))
   .action(async (options: SetupCommandOptions) => {
     await Gitarist.setup({ remote: options.remote });
@@ -24,7 +27,9 @@ program
 
 program
   .command('start')
-  .description('start gitarist suite')
+  .description(
+    'It starts gitarist suite. It simulates an active user on a GitHub repository to create issues, commits, create a pull request, and merge it.',
+  )
   .addOption(new Option('-o,--owner <string>', 'Repository owner').env('GITHUB_OWNER'))
   .addOption(new Option('-r,--repo <string>', 'GitHub repository').env('GITHUB_REPO'))
   .addOption(
@@ -66,7 +71,9 @@ program
     new Option('--stale <days>', 'A number of days before closing an issue').default(DEFAULT.stale),
   )
   .action(async (options: Partial<StartCommandOptions>) => {
-    dotenv.config({ path: '.env' });
+    ['.env'].forEach((file) => {
+      dotenv.config({ path: file });
+    });
 
     options = {
       ...options,
@@ -106,7 +113,6 @@ program
       repo: validOptions.repo,
       token: validOptions.token,
     });
-
     await gitarist.simulateActiveUser({
       mainBranch: validOptions.mainBranch,
       maxCommits: validOptions.maxCommits,
@@ -119,4 +125,31 @@ program
     });
   });
 
+program
+  .command('env-example')
+  .description('Create an example of .env file based on the current .env file(s)')
+  .addOption(
+    new Option(
+      '-f,--filename <string>',
+      'Read given env file such as .env.local, .env.test etc.',
+    ).default('.env'),
+  )
+  .addOption(new Option('-c,--comments', 'Preserve comments').default(true))
+  .addOption(new Option('-m,--merge', 'Merge all env files into one').default(true))
+  .action(async (options: CreateEnvExampleOptions) => {
+    const validOptions = z
+      .object({
+        comments: z.boolean(),
+        filename: z
+          .string()
+          .min(1)
+          .refine((arg) => arg !== '.env.example', {
+            message: 'filename should not be .env.example',
+          }),
+        merge: z.boolean(),
+      })
+      .parse(options);
+    await createEnvExample(validOptions);
+  });
+
 program.parse();
diff --git a/src/libs/env-example.spec.ts b/src/libs/env-example.spec.ts
new file mode 100644
index 0000000..96c48d7
--- /dev/null
+++ b/src/libs/env-example.spec.ts
@@ -0,0 +1,75 @@
+describe('env-example', () => {
+  it('should create an example .env file', async () => {
+    //     // Arrange
+    //     const filename = '.env.sample';
+    //     const comments = true;
+    //     const merge = true;
+    //     const expectedOutput = `# GITHUB_OWNER=
+    // GITHUB_REPO=
+    // GITHUB_TOKEN=
+    // `;
+    //     const fs = {
+    //       readFileSync: jest.fn().mockReturnValue(`GITHUB_OWNER=
+    // GITHUB_REPO
+    // GITHUB_TOKEN
+    // `),
+    //       writeFileSync: jest.fn(),
+    //     };
+    //     const path = {
+    //       join: jest.fn().mockReturnValue('.env'),
+    //     };
+    //     const process = {
+    //       cwd: jest.fn().mockReturnValue('/path/to/cwd'),
+    //     };
+    //     await createEnvExample({ filename, comments, merge });
+    //     expect(fs.readFileSync).toHaveBeenCalledWith('/path/to/cwd/.env', 'utf8');
+    //     expect(fs.writeFileSync).toHaveBeenCalledWith('/path/to/cwd/.env.example', expectedOutput, {
+    //       encoding: 'utf-8',
+    //       flag: 'w+',
+    //     });
+  });
+
+  afterAll(async () => {
+    // execSync('rm -f .env.invalid');
+    // execSync('rm -f .env.valid');
+  });
+
+  it('should throw an error if a line does not have a valid config', async () => {
+    const envContent = `GITHUB_OWNER="foo"
+GITHUB_REPO="bar"
+GITHUB_REPO="bar"
+GITHUB_REPO="bar"
+GITHUB_REPO="bar"
+GITHUB_TOKEN="baz"
+
+########################################################
+
+GITLAB_HOST="foo"
+GITLAB_HOST="foo"
+GITLAB_HOST="foo"
+GITLAB_HOST="foo"
+GITLAB_HOST="foo"
+GITLAB_TOKEN="bar"
+# project token
+GITLAB_TOKEN="baz" 
+GITLAB_PROJECT_ID="1234"
+
+########################################################
+
+# Profile > Personal Access Tokens > Create API Token
+JIRA_TOKEN="foo"
+JIRA_PROJECT_KEY="bar"
+JIRA_HOST="baz"
+JIRA_HOST="baz"
+JIRA_HOST="baz"
+JIRA_HOST="baz"
+`;
+    // execSync(`echo ${envContent} > .env.valid`);
+
+    // createEnvExample({
+    //   filename: ' .env.valid',
+    //   comments: true,
+    //   merge: true,
+    // });
+  });
+});
diff --git a/src/libs/env-example.ts b/src/libs/env-example.ts
new file mode 100644
index 0000000..08edff3
--- /dev/null
+++ b/src/libs/env-example.ts
@@ -0,0 +1,44 @@
+import fs from 'fs';
+import path from 'path';
+
+export type CreateEnvExampleOptions = {
+  filename: string;
+  comments: boolean;
+  merge: boolean;
+};
+
+export async function createEnvExample(options: CreateEnvExampleOptions) {
+  const keySet = new Set<string>();
+  const output = fs
+    .readFileSync(path.join(process.cwd(), options.filename), 'utf8')
+    .split('\r')
+    .join('')
+    .split('\n')
+    .map((line) => line.trim())
+    .map((line, index) => {
+      if (line === '') {
+        return '';
+      }
+      if (line.startsWith('#')) {
+        return options.comments ? line : null;
+      }
+      if (line.indexOf('=') === -1) {
+        throw new Error(`Line ${index} does not have a valid config (i.e. no equals sign).`);
+      }
+      const key = line.split('=')[0];
+      if (options.merge && keySet.has(key)) {
+        return null;
+      } else {
+        keySet.add(key);
+        return key + '=';
+      }
+    })
+    .filter((line) => line !== null)
+    .join('\n');
+
+  fs.writeFileSync(path.join(process.cwd(), '.env.example'), output, {
+    encoding: 'utf-8',
+    flag: 'w+',
+  });
+  console.log('✨ .env.example successfully generated.');
+}
diff --git a/src/libs/index.ts b/src/libs/index.ts
new file mode 100644
index 0000000..6af2fd0
--- /dev/null
+++ b/src/libs/index.ts
@@ -0,0 +1 @@
+export * from './env-example';