/** Shared helpers for drive-resident /bin scripts (prepended before each command). */
function bareStdin(ctx) {
  return typeof ctx.shellStdin === 'string' ? ctx.shellStdin : ''
}

async function run(ctx, argv) {
  const vfs = ctx.vfs
  let n = 10
  let start = 1
  if (argv[1] === '-n' && argv[2]) {
    n = parseInt(argv[2], 10) || 10
    start = 3
  }
  const files = argv.slice(start).filter((a) => a !== '--')
  const take = (s) => {
    let lines = s.split('\n')
    if (s.endsWith('\n') && lines[lines.length - 1] === '') lines.pop()
    const slice = lines.length <= n ? lines : lines.slice(-n)
    ctx.console.log(slice.join('\n'))
  }
  if (!files.length) {
    take(bareStdin(ctx))
    return
  }
  for (const f of files) {
    const buf = await vfs.readFile(f)
    if (!buf) {
      ctx.console.error('tail: ' + f + ': No such file')
      continue
    }
    if (files.length > 1) ctx.console.log('==> ' + f + ' <==')
    take(ctx.b4a.toString(buf))
  }
}