dotfiles

Shell, editor and terminal configuration, the tools that go with them, and
szecret, an age-based secret manager whose store lives elsewhere.

History restarts here. What came before was not written to be read by
anyone else, and carried machine names, addresses and an encrypted secret
store; it is kept privately instead. What is left is meant to be safe on
any machine, including one whose owner is not me: see CLAUDE.md for the
rule it is written to.

1 files changed, 105 insertions, 0 deletions

diff --git a/bin/random-id.ts b/bin/random-id.ts
new file mode 100755
index 0000000..b8bf364
--- /dev/null
+++ b/bin/random-id.ts
@@ -0,0 +1,105 @@
+#!/usr/bin/env node --disable-warning=DEP0180  --no-warnings 
+
+const idChars = (function (): string[] {
+  const chars: string[] = [];
+
+  function code(x: string | number): number {
+    return typeof x === "string" ? x.charCodeAt(0) : x;
+  }
+
+  function add(from: string | number, to: string | number): void {
+    const fromCode = code(from);
+    const toCode = code(to);
+    for (let c = fromCode; c <= toCode; ++c) {
+      chars.push(String.fromCharCode(c));
+    }
+  }
+
+  add("0", "9");
+  add("a", "z");
+  add("A", "Z");
+  return chars;
+})();
+
+
+/*
+Alphabet size: 62 characters (A–Z, a–z, 0–9)
+Total possible IDs of length n: TOTAL_IDS = 62^n
+To compute the probability that two randomly generated IDs collide (i.e., are identical): P_COLLISION = 1 / TOTAL_IDS
+
+==========================================================
+ ID Length | ID space       |  P(Collision)  | Intuition
+-----------|----------------|----------------|------------
+     5     |   916,132,832  |  ~1.09 × 10⁻⁹  | ~1 in a billion (like lottery odds)
+     6     | 56,800,235,584 |  ~1.76 × 10⁻¹¹ | ~1 in 50 billion (world population × 6)
+    17     |   2.96 × 10³⁰  |  ~3.38 × 10⁻³¹ | ~1 in a nonillion (grains of sand × 10¹⁹)
+==========================================================
+
+Interpretation:
+- At **length 5**, collisions are rare but not implausible if generating millions of IDs.
+- At **length 6**, collisions are extremely rare - safe for most casual uses.
+- At **length 17**, collisions are cosmically unlikely—about as probable as picking the same atom out of all atoms in the solar system.
+
+==========================================================
+== Out of a pool of 100,000 ===
+
+Alphabet size: 62 characters (A–Z, a–z, 0–9)  
+Existing IDs: N = 100 000
+
+Formulas:
+  TOTAL_IDS(n)      = 62^n
+  P_match_one       = 1 / TOTAL_IDS(n)
+  P_collision_any   = 1 − (1 − P_match_one)^N
+
+--------------------------------------------------------------------------------
+ n | TOTAL_IDS(n)        | P_collision_any                | Intuition
+---+----------------------+--------------------------------+-------------------------------------------
+ 5 | 62^5 = 916 132 832   | 1 − (1 − 1/916 132 832)^100 000  
+    |                      | ≈ 1.09 × 10⁻⁴                  | ~0.01% → ~1 in 9 200  
+    |                      |                                | (about as rare as drawing the same  
+    |                      |                                | lottery number in ~9 200 draws)
+
+ 6 | 62^6 = 56 800 235 584| ≈ 1.76 × 10⁻⁶                  | ~0.000176% → ~1 in 568 000  
+    |                      |                                | (like finding a specific LEGO  
+    |                      |                                | brick in a pile of half a million)
+
+ 8 | 62^8 ≈ 2.18 × 10^14   | ≈ 4.58 × 10⁻¹⁰                 | ~4.6 × 10⁻⁸% → ~1 in 2.2 billion  
+    |                      |                                | (on par with winning a major lottery)
+
+17 | 62^17 ≈ 2.96 × 10^30  | ≈ 3.38 × 10⁻²⁶                 | ~3.4 × 10⁻²⁴% → ~1 in 3 × 10^25  
+    |                      |                                | (effectively zero—astronomically  
+    |                      |                                | unlikely, far beyond grains of sand  
+    |                      |                                | on every beach on Earth)
+--------------------------------------------------------------------------------
+
+Reasoning:
+- TOTAL_IDS(n) counts all possible length-n strings.  
+- P_match_one = chance it matches one given ID.  
+- With N existing, P_collision_any = 1 minus the chance it misses all N.  
+- For n=5 collisions are possible if you generate many IDs; for n≥8 they're vanishingly rare; for n=17 they're effectively impossible in any realistic system.
+
+ */
+
+// With 62 possible chars, a 17 char long ID has about 10^30 possible values,
+// the chance of finding any of 8 billion of them is about the same as the
+// chance of finding a single specific grain of sand in on earth.
+//
+const idLength = process.env.ID_LENGTH ? parseInt(process.env.ID_LENGTH) :17;
+
+function randomId(length: number = idLength): string {
+  const chars: string[] = [];
+  for (let i = 0; i < length; ++i) {
+    const c = Math.floor(Math.random() * idChars.length);
+    chars.push(idChars[c]!);
+  }
+  return chars.join("");
+}
+
+// take count from from first argument, default to 1
+const count = parseInt(process.argv[2] || "1");
+
+// execute and print
+for (let i = 0; i < count; ++i) {
+  console.log(randomId());
+}
+