go-process-cli

Go Process-Management CLIs

Make Go command-line tools that spawn, supervise, and shut down processes correctly — the part the stdlib makes easy to get subtly wrong.

When to Apply

Reach for this skill when building or reviewing a Go CLI whose job is to control other processes or concurrent workloads: a daemon, a process supervisor, a job/worker runner, a deploy or migration tool, a test harness that shells out, or any program that must stop cleanly when an orchestrator says so. It targets Go 1.22+ on Unix-like systems (Linux, macOS); a few rules note where Windows differs. It assumes you already know Go — it only corrects the specific defaults that go wrong in this domain.

Categories

Quick Reference

The defaults this skill exists to correct:

• signal.NotifyContext(ctx, SIGINT, SIGTERM) — not a channel that only watches Ctrl-C. Orchestrators send SIGTERM.
• exec.CommandContext + cmd.Cancel/cmd.WaitDelay — plain CommandContext SIGKILLs children with no cleanup.
• Setpgid + kill(-pgid) — signalling the direct child orphans grandchildren (sh -c, make, npm).
• cmd.Output() for capture — reading a pipe after Wait() deadlocks.
• errgroup.WithContext + SetLimit(n) — a goroutine per task means a process per task: PID/FD exhaustion.
• ctx as an argument — never a struct field; defer cancel() on every derived context.
• select { case <-ticker.C: case <-ctx.Done(): } — time.Sleep makes shutdown wait out the interval.
• main → run() error → os.Exit(1) — log.Fatal/os.Exit deep in code skip every defer.
• proc.Signal(syscall.Signal(0)) — os.FindProcess always succeeds on Unix; it never proves liveness.
• os.OpenFile(O_CREATE|O_EXCL) for PID files — check-then-create is a race; cmd.Wait() every child or it zombifies.