async function run(ctx, argv) {
  if (argv.length < 2) {
    ctx.console.error('usage: sh [-eu] [-s | -c COMMAND | SCRIPT]')
    ctx.exitCode = 2
    return
  }
  if (typeof ctx.execLine !== 'function') {
    ctx.console.error('sh: execLine is not available (requires a Bare OS booter session)')
    ctx.exitCode = 1
    return
  }

  const vfsEnv =
    ctx.vfs?.env && typeof ctx.vfs.env === 'object' ? ctx.vfs.env : null
  let i = 1
  let sawFlags = false
  while (i < argv.length) {
    const a = argv[i]
    if (a === '--') {
      i++
      break
    }
    if (a === '-' || !a.startsWith('-')) break
    if (a === '-c' || a === '-s') break
    sawFlags = true
    for (const ch of a.slice(1)) {
      if (ch === 'e' && vfsEnv) vfsEnv.BARE_OS_SHELL_ERREXIT = '1'
      else if (ch === 'u' && vfsEnv) vfsEnv.BARE_OS_SHELL_NOUNSET = '1'
      else if (ch === 'v' && vfsEnv) vfsEnv.BARE_OS_SHELL_XTRACE = '1'
      else if (ch === 'x' && vfsEnv) vfsEnv.BARE_OS_SHELL_XTRACE = '1'
      else if (ch === 'C' && vfsEnv) vfsEnv.BARE_OS_SHELL_NOCLOBBER = '1'
    }
    i++
  }

  const mode = argv[i]
  if (mode == null && !sawFlags) {
    ctx.console.error('usage: sh [-eu] [-s | -c COMMAND | SCRIPT]')
    ctx.exitCode = 2
    return
  }

  if (mode === '-c') {
    const command = argv[i + 1]
    if (command == null) {
      ctx.console.error('sh: option requires an argument -- c')
      ctx.console.error('usage: sh -c COMMAND [NAME [ARG ...]] | sh SCRIPT')
      ctx.exitCode = 2
      return
    }
    const env = ctx.vfs?.env
    /** @type {Record<string, string | undefined> | null} */
    const saved = env && typeof env === 'object' ? {} : null
    if (saved && env) {
      for (const k of ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '#']) {
        saved[k] = env[k]
      }
      env['0'] = argv[i + 3] ?? 'sh'
      const args = argv.slice(i + 4)
      for (let j = 1; j <= 9; j++) env[String(j)] = args[j - 1] ?? ''
      env['#'] = String(args.length)
    }
    try {
      await ctx.execLine(command)
      const v = ctx.vfs?.env?.BARE_OS_EXIT_STATUS
      const n = Number.parseInt(String(v ?? ''), 10)
      if (Number.isFinite(n)) ctx.exitCode = n
    } finally {
      if (saved && env) {
        for (const [k, v] of Object.entries(saved)) {
          if (v == null) delete env[k]
          else env[k] = v
        }
      }
    }
    return
  }

  if (mode === '-s') {
    const stdinText =
      typeof ctx.shellStdin === 'string'
        ? ctx.shellStdin
        : typeof ctx.shellStdin === 'object' &&
            ctx.shellStdin &&
            'data' in ctx.shellStdin
          ? String(/** @type {{ data?: string }} */ (ctx.shellStdin).data ?? '')
          : ''
    await runShScriptText(ctx, stdinText, { label: 'stdin' })
    return
  }

  const script = mode
  let buf
  try {
    buf = await ctx.vfs.readFile(script)
  } catch (e) {
    ctx.console.error('sh: ' + ((e && e.message) || String(e)))
    ctx.exitCode = 1
    return
  }
  if (buf == null) {
    ctx.console.error('sh: ' + script + ': not found')
    ctx.exitCode = 127
    return
  }
  let text = ctx.b4a.toString(buf)
  if (text.charCodeAt(0) === 0xfeff) text = text.slice(1)
  text = text.replace(/^\ufeff/, '')
  if (text.startsWith('#!')) {
    const nl = text.indexOf('\n')
    text = nl === -1 ? '' : text.slice(nl + 1)
  }
  await runShScriptText(ctx, text, { label: script })
}

/**
 * @param {Record<string, unknown>} ctx
 * @param {string} text
 * @param {{ label: string }} meta
 */
async function runShScriptText(ctx, text, meta) {
  text = String(text || '').replace(/\\\r?\n/g, '')
  const lines = text.split(/\r?\n/)
  const blocks = []
  let cur = ''
  let depth = 0
  for (let i = 0; i < lines.length; i++) {
    const raw = lines[i]
    const trimmed = raw.trim()
    if (!trimmed || trimmed.startsWith('#')) continue
    cur += (cur ? '\n' : '') + raw
    const words = trimmed
      .replace(/[;(){}]/g, ' ')
      .split(/\s+/)
      .filter(Boolean)
    for (const w of words) {
      if (w === 'if' || w === 'for' || w === 'while' || w === 'until' || w === 'case')
        depth++
      else if (w === 'fi' || w === 'done' || w === 'esac') depth = Math.max(0, depth - 1)
    }
    if (depth === 0) {
      blocks.push(cur)
      cur = ''
    }
  }
  if (cur.trim()) blocks.push(cur)
  let lineNo = 1
  for (const block of blocks) {
    const env = ctx.vfs?.env
    if (env && typeof env === 'object') {
      env.BARE_OS_SH_SCRIPT_LABEL = meta.label
      env.BARE_OS_SH_SCRIPT_LINE = String(lineNo)
    }
    await ctx.execLine(block)
    lineNo += block.split(/\r?\n/).length
    if ((Number(ctx.exitCode) || 0) !== 0) return
  }
  ctx.exitCode = 0
}