Function updateDotEnv

packages/cli/src/utils/dotenv.ts:92–139

(filePath: string, updates: Record<string, string>)

 * @param updates - Object mapping variable names to their new values
 */
export async function updateDotEnv(filePath: string, updates: Record<string, string>): Promise<void> {
  let content = ''

  try {
    content = await fs.readFile(filePath, 'utf-8')
  } catch (error) {
    if (!isErrnoENOENT(error)) {
      throw error
    }
    // File doesn't exist, we'll create it
  }

  const pendingUpdates = new Set(Object.keys(updates))

  // Replace existing variables using regex
  for (const key of Object.keys(updates)) {
    // Match KEY=... until end of line (handles quoted and unquoted values)
    const regex = new RegExp(`^(${escapeRegex(key)})=.*$`, 'm')
    if (regex.test(content)) {
      content = content.replace(regex, `${key}=${formatValue(updates[key])}`)
      pendingUpdates.delete(key)
    }
  }

  // Append new variables at the end
  for (const key of pendingUpdates) {
    const formattedLine = `${key}=${formatValue(updates[key])}`

    if (content === '') {
      content = formattedLine
    } else if (content.endsWith('\n')) {
      content += formattedLine
    } else {
      content += `\n${formattedLine}`
    }
  }

  // Ensure trailing newline
  if (content !== '' && !content.endsWith('\n')) {
    content += '\n'
  }

  // Ensure parent directory exists
  const dir = path.dirname(filePath)
  await fs.mkdir(dir, { recursive: true })

  await fs.writeFile(filePath, content, 'utf-8')
}

/**
 * Escape special regex characters in a string.