wait_on ☆

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Description:
Provides shell scripts with access to kqueue(3)

Type: Formula | Latest Version: 1.1@0 | Tracked Since: Oct 30, 2025

Links: Homepage | formulae.brew.sh

Category: System utilities

Tags: kqueue shell-scripting cli monitoring event-driven

Install: brew install wait_on

About:
wait_on is a command-line utility that leverages the kqueue(3) system call to monitor file descriptors for events. It allows shell scripts to efficiently wait for I/O readiness, process termination, or signal events without busy-waiting. This provides a lightweight and highly efficient alternative to polling-based methods for event-driven scripting.

Key Features:

Monitors file descriptors for read/write readiness using kqueue
Watches for process exit events
Supports signal event notification
Designed for use in shell scripts and command pipelines

Use Cases:

Building efficient, event-driven shell scripts
Monitoring multiple processes or network sockets concurrently
Creating responsive daemons or service supervisors

Alternatives:

inotifywait – Linux-specific, focused on filesystem events; wait_on is more general (I/O, processes, signals) and uses kqueue (BSD/macOS).
poll – Standard POSIX utility; less efficient and lacks integrated process/signal monitoring compared to wait_on's kqueue integration.

Version History

Detected	Version	Rev	Change	Commit
Oct 30, 2025 7:30pm		0	VERSION_BUMP	ba5a1e48