Update man to add the manual guide

kernel/bin/tr

@@ -0,0 +1,95 @@
+/** Shared helpers for drive-resident /bin scripts (prepended before each command). */
+function bareStdin(ctx) {
+  return typeof ctx.shellStdin === 'string' ? ctx.shellStdin : ''
+}
+
+/** @param {number} mode @param {'file' | 'directory' | 'symlink'} type */
+function bareFormatModeString(mode, type) {
+  const typeChar =
+    type === 'directory' ? 'd' : type === 'symlink' ? 'l' : '-'
+  const perm = mode & 0o777
+  const r = (bit) => (perm & bit ? 'r' : '-')
+  const w = (bit) => (perm & bit ? 'w' : '-')
+  const x = (bit) => (perm & bit ? 'x' : '-')
+  return (
+    typeChar +
+    r(0o400) +
+    w(0o200) +
+    x(0o100) +
+    r(0o040) +
+    w(0o020) +
+    x(0o010) +
+    r(0o004) +
+    w(0o002) +
+    x(0o001)
+  )
+}
+
+/** @param {number} mtimeMs @param {number} [nowMs] */
+function bareFormatLsMtime(mtimeMs, nowMs) {
+  const now = nowMs != null ? nowMs : Date.now()
+  const d = new Date(mtimeMs)
+  const months = [
+    'Jan',
+    'Feb',
+    'Mar',
+    'Apr',
+    'May',
+    'Jun',
+    'Jul',
+    'Aug',
+    'Sep',
+    'Oct',
+    'Nov',
+    'Dec'
+  ]
+  const mon = months[d.getMonth()]
+  const day = String(d.getDate()).padStart(2, ' ')
+  const sixMo = 180 * 24 * 3600 * 1000
+  if (Math.abs(now - mtimeMs) > sixMo) {
+    const yr = String(d.getFullYear()).padStart(4, ' ')
+    return mon + ' ' + day + '  ' + yr
+  }
+  const hh = String(d.getHours()).padStart(2, '0')
+  const mm = String(d.getMinutes()).padStart(2, '0')
+  return mon + ' ' + day + ' ' + hh + ':' + mm
+}
+
+/** @param {number} size */
+function barePosixBlocks(size) {
+  return Math.ceil(Number(size) / 512) || 0
+}
+
+async function run(ctx, argv) {
+  let del = false
+  const sets = []
+  for (let i = 1; i < argv.length; i++) {
+    if (argv[i] === '-d' || argv[i] === '--delete') del = true
+    else if (argv[i] !== '--') sets.push(argv[i])
+  }
+  if (!sets.length || (!del && sets.length < 2)) {
+    ctx.console.error('usage: tr [-d] SET1 [SET2]')
+    ctx.exitCode = 1
+    return
+  }
+  const s = bareStdin(ctx)
+  if (del) {
+    const kill = new Set(sets[0].split(''))
+    let o = ''
+    for (const ch of s) if (!kill.has(ch)) o += ch
+    ctx.console.log(o)
+    return
+  }
+  const from = sets[0]
+  const to = sets[1]
+  const map = Object.create(null)
+  const n = Math.max(from.length, to.length)
+  for (let i = 0; i < n; i++) {
+    const fc = from[i] || from[from.length - 1]
+    const tc = to[i] != null ? to[i] : to[to.length - 1] || ''
+    map[fc] = tc
+  }
+  let o = ''
+  for (const ch of s) o += map[ch] != null ? map[ch] : ch
+  ctx.console.log(o)
+}