pend – do now, wait later 🕒

pend is a tiny cross-platform job runner that lets you fire-and-forget processes now and deal with their output later – all while keeping logs tidy, exit statuses intact, and your shell scripts blissfully simple.

# Run two jobs in parallel …
pend do backend ./scripts/build_backend.sh
pend do frontend ./scripts/build_frontend.sh

# … wait for them whenever you want (combined coloured output!)
pend wait backend frontend

# Clean up once you are done
pend clean --all

Why wrestle with &, wait, and brittle tee pipelines when one binary does all the heavy lifting for you?

📦 Installation

cargo install pend      # Rust way – zero dependencies
# or grab a pre-built release asset from GitHub

The crate is 100 % Rust, no native libraries, so a static binary drops out on all tier-1 platforms (Windows / macOS / Linux – x86-64 & aarch64).

🧠 Mental model

That’s the entire user-facing surface – four deliberately boring verbs.

✨ What you get – out of the box

• Structured artifacts – every job yields predictable files: .out, .err, .log, .exit, .json, .signal (Unix) – all plain text or JSON.

• Crash-safe exit codes – the .exit marker is written before log pipes are closed so pend wait never hangs on a half-dead worker.

• Coloured multi-job output – pend wait a b c interleaves logs with deterministic colours and clear ✓ / ✗ status lines.

• Size-bounded log rotation – --max-log-size 10M keeps CI artifacts small yet complete. • Wall-clock timeout – pend do <job> --timeout 30 <cmd …> terminates runaway processes after 30 s and marks the job as failed. • Automatic retries – --retries 3 re-runs flaky commands up to three times until one attempt succeeds.

• Strong validation & security – path traversal is impossible, job names are capped at 100 characters, and an advisory .lock prevents concurrent duplicates.

• Platform quirks handled – symlink tmpdirs on macOS, MAX_PATH on Windows, signals on Unix – tested on all three major OSes in CI.

• Single static binary – integrates into any Bash / PowerShell / CMD script without pulling in a runtime.

🔍 Artifact layout

Jobs live in a single directory (defaults to $TMPDIR/pend, override via --dir or PEND_DIR). Files follow <job>.<ext>:

Everything is human-readable → cat, jq, or even Notepad work fine.

🚀 Example: parallel build & package

# Kick off long-running tasks
pend do backend docker build .
pend do frontend npm run build

# Meanwhile run unit tests …
pytest -q

# Stream & fail fast once the first build fails
pend wait backend frontend

# Ensure the linter finishes within 60 seconds and automatically retries once
# if it flaps due to I/O hiccups.
pend do lint --timeout 60 --retries 1 npm run lint
pend wait lint

# Package artifacts only if both succeeded
pend do package ./scripts/package.sh
pend wait package

# Upload artifacts, then clean workspace
pend clean package

🛠 Under the hood

• Worker process – spawns child cmd, merges pipes via channel fan-in, writes JSON, exits.
• File watcher – pend wait uses the cross-platform notify crate for instant .exit detection; falls back to exponential back-off polling if necessary.
• No async runtime – plain threads & channels keep the binary small (< 1 MiB on Linux/musl).

📚 Prior art

GNU parallel, xargs -P, make -j, ninja, taskwarrior, just, cargo-make … all wonderful – yet none hit the sweet spot of ad-hoc, nameable, parallel shell jobs with deterministic logs.

pend does.

Made with ❤️ & Rust – so you can do now, wait later.