Bash

Find + Replace Across Many Files

Use `find` + `sed -i` to do project-wide refactors. Always test the regex first with a dry run.

6h ago 0

Rust

Parse Strings to Typed Values

`str::parse::<T>()` works for every type that implements `FromStr` — every numeric type, `bool`, `IpAddr`, `Uuid` (with the crate), etc. Returns `Result` so you can chain with `?`.

6h ago 0

Python

functools.cache Memoization

Wrap any pure function with @cache (Python 3.9+) and get an unbounded memoization layer for free. Use @lru_cache(maxsize=N) when you need a bounded cache.

6h ago 0

Bash

cURL GET with Timeout + Retry

A sensible default cURL invocation: short connect timeout, total timeout, retry on transient failures with backoff, fail-on-error.

6h ago 0

Bash

OS / Distro Detection

Read /etc/os-release for distro info — it's the standard on every modern Linux. Branch deploy scripts on distro to pick apt vs. dnf vs. apk.

6h ago 0

Rust

Slice Pattern: Borrow Without Copy

A slice (`&[T]`) is a borrowed view into a contiguous sequence. Pass `&v[..]` or just `&v` instead of `v.clone()` when the function only needs to read.

6h ago 0

Rust

Unit Tests with #[test] and assert_eq!

Tests live alongside the code they test. `cargo test` runs every `#[test]` function. Use `#[cfg(test)] mod tests` so the test code is compiled out of release builds.

6h ago 0

HTML

Progress and Meter Elements

`<progress>` shows how much of a task is done (downloads, multi-step forms). `<meter>` shows a value within a known range (disk usage, password strength). Both render as native UI in every browser.

6h ago 0

TypeScript

uniqueBy — Dedupe by Callback

Deduplicate an array using a derived key (object id, lowercased email, etc.). First occurrence wins. Backed by a Map for O(n) performance.

6h ago 0

Go

os.Getenv with Defaults

`os.Getenv` returns "" when unset — easy to miss. Wrap it with a typed helper that supplies defaults and parses numerics. Saves boilerplate at every config-read site.

6h ago 0

Python

ProcessPoolExecutor for CPU-Bound Work

Use processes (not threads) for CPU-bound work to sidestep the GIL. Functions must be picklable — define them at module level, not as locals or lambdas.

6h ago 0

Go

Struct Embedding (Composition over Inheritance)

Go has no inheritance. Embed a type to "promote" its fields and methods as if they were on the outer type. Same effect as inheritance for most purposes, but explicit.

6h ago 0

PHP

Safe Path Join

Concatenate path segments and produce a normalized canonical path that resists "../" escape attempts. Throws if the result would land outside the given base directory.

6h ago 0

Python

textwrap dedent + fill (Multi-line Strings)

`textwrap.dedent` strips common leading whitespace from a triple-quoted string — finally, you can indent multiline strings inside functions without breaking the formatting. `fill` wraps to a max width.

6h ago 0

PHP

TOTP Code Generate + Verify

Generate and verify a 6-digit time-based one-time password (RFC 6238) compatible with Google Authenticator / Authy. Uses a base32-encoded secret and 30-second time steps.

6h ago 0

PHP

Generate Secure API Key

Mint an API key with a recognizable prefix ("sk_live_…") and 32 bytes of crypto-random entropy encoded as URL-safe base64. Stripe-style readable IDs.

6h ago 0

Bash

Generate UUID

Several portable ways to mint a v4 UUID from the shell — useful for request IDs, idempotency keys, temporary filenames.

6h ago 0

PHP

RGB ↔ Hex Conversion

Two-way conversion between #RRGGBB hex strings and [R, G, B] arrays. Handy when working with theme colors that come from both sources (CSS strings vs. RGB sliders).

6h ago 0

Bash

Atomic File Write (write then rename)

Write to a temp file in the SAME directory, then `mv` to the final name. mv on the same filesystem is atomic — readers never see a half-written file.

6h ago 0

Bash

Read File Line-By-Line (the safe way)

The classic `for line in $(cat file)` is wrong — it word-splits and globbing fires on filenames. Use `while IFS= read -r line` with input redirection.

6h ago 0

Python

Safe JSON Read/Write

Idiomatic helpers for reading + writing JSON to disk, with atomic writes and pretty-printed output. Catches the common "edit and save → corrupt file on crash" failure mode.

6h ago 0

Rust

String vs &str — The Cheat Sheet

`String` is an owned, growable heap allocation; `&str` is a borrowed view into a UTF-8 buffer. Function params should usually take `&str`; return types use `String` when ownership is needed.

6h ago 0

Go

CSV Read/Write with encoding/csv

`encoding/csv` parses RFC 4180 CSVs. Read row-by-row with `Read()` or all at once with `ReadAll()`. Same for writing — flush with `Writer.Flush()` before closing.

6h ago 0

Rust

Atomic File Write (tempfile + persist)

Write to a temp file in the SAME directory, then atomically `persist` (rename). The `tempfile` crate handles cleanup if you crash before persisting.

6h ago 0

Go

JSON API Endpoint

Decode an incoming JSON body into a typed struct, do work, encode a JSON response. The whole roundtrip is ~20 lines of standard library.

6h ago 0

PHP

Atomic File Write

Write a file in a way that other processes never see a half-written state. Write to a temp file in the same directory, then rename — rename is atomic on POSIX filesystems.

6h ago 0

Bash

Associative Array (hash map)

Bash 4+ supports key-value associative arrays. Must `declare -A` first — Bash won't infer it. Iterate keys with !arr[@].

6h ago 0

Bash

SSH to Multiple Hosts in Parallel

Run the same command on a fleet of hosts. Three patterns: serial loop (simplest), GNU parallel (fastest), pssh (purpose-built).

6h ago 0

Rust

axum with Shared State + Extractors

Use `State` to inject shared application state (DB pool, config, etc.) into every handler. `Path` and `Json` extractors deserialize URL params and request bodies for you.

6h ago 0

JavaScript

Memoize Function

Caches the result of a pure function keyed by its serialised arguments. On repeated calls with the same inputs the cached value is returned instantly, skipping expensive computation. Supports single and multi-argument functions via JSON key serialisation.

6h ago 0