Go CLI Process Control

Treat child-process lifecycle as correctness. Observe the terminal result, propagate cancellation, and clean up every process, pipe, and temporary resource.

Core Workflow

1. Define the child executable, argv, environment, directory, streams, and success contract.
2. Use an explicit shell only when shell semantics are actually required.
3. Inject a runner boundary and propagate the caller's context.
4. Observe startup and completion; preserve status and useful redacted stderr.
5. Bound captured output, cancellation, and shutdown time.
6. Account for descendants and wait for every pipeline stage.
7. Test missing tools, bad exits, malformed output, cancellation, signals, and cleanup.

Read Next

| Task | Load | |---|---| | Implement or repair process supervision | guidelines.md, workflows/supervise-external-command.md | | Apply modern execution and cancellation rules | references/process-control/rules.md | | Use runner, pipeline, signal, or cleanup patterns | references/process-control/patterns.md | | Start from focused code examples | references/process-control/examples.md | | Review a subprocess boundary | references/process-control/checklist.md | | Understand lifecycle and shell semantics | references/process-control/knowledge.md |

Guardrails

• Pass executable arguments separately; never assume exec.Command invokes a shell.
• Do not treat Start as success; inspect the terminal result.
• Do not assume context cancellation terminates an entire process tree.
• Close owned pipes and wait for every started process.
• Distinguish lookup, start, exit, timeout, cancellation, and cleanup failures.
• Treat Cmd.String() as diagnostic text, never shell-safe replay or secret-safe output.
• Avoid mutable package-level command hooks in concurrent tests.

Source Notes

Guidance is transformed and paraphrased from Ricardo Gerardi, Powerful Command-Line Applications in Go (Pragmatic Bookshelf, 2021), especially Chapter 6. Examples are original adaptations.

Book: https://pragprog.com/titles/rggo/powerful-command-line-applications-in-go/

Verify current behavior against https://pkg.go.dev/os/exec and https://pkg.go.dev/os/signal, including Cmd.Cancel, WaitDelay, and signal.NotifyContext.

Failure taxonomy, pipe ordering, and platform-adapter guidance also incorporates transformed material from Marian Montagnino, Building Modern CLI Applications in Go (Packt, 2023), especially Chapter 6.

In-process cancellation boundary guidance also incorporates transformed material from Inanc Gumus, Go by Example: Programmer's Guide to Idiomatic and Testable Programs (Manning, 2025), Chapters 6-7.