unix
8 minpipefail, Signals, and Unix Process Management
Unix is full of tiny control primitives. Learn how `set -o pipefail`, process signals, and clean lifecycle management keep shell pipelines reliable and debuggable.
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unix
7 minUnix Signals and Child Processes: What Your Service Must Clean Up
Follow signals from a container stop through shell wrappers and child processes, and build shutdown behavior that preserves work.
devops
5 minDevOps Foundations: Safe Changes, Health Signals, and Rollback Boundaries
Design a release as a controlled change to code, configuration, and data, with explicit health checks and a recovery plan that matches what can actually be reversed.
devops
8 minProduction Observability: Signals, Service Objectives, and Useful Alerts
Build an operational view around user-visible latency, traffic, errors, and saturation instead of dashboards full of disconnected metrics.
Q&A
Q&AWhy use exec in a container entrypoint script?
Replacing the shell with the service improves signal delivery and exit-code propagation.
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Without exec, the shell can remain as the parent process and may not forward termination signals as intended. `exec service ...` replaces the shell, making the service the main process so it receives the container stop signal directly and its exit status is reported. A wrapper supervising multiple children must explicitly forward signals and reap them.
distributed systems
8 minCausal order: what a logical clock can and cannot tell you
Distinguish event causality from wall-clock order with Lamport and vector clocks.
Q&A
Q&AWhy can a Linux filesystem be full when du shows free space?
Inodes may be exhausted, or deleted files may still be held open by running processes.
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Compare df -h with df -i. If block usage and directory totals disagree, inspect open-but-deleted files with lsof +L1. A process retains allocated blocks until it closes the file; restart or signal the owning service through its safe lifecycle after confirming the file is disposable.
Q&A
Q&AWhy does Spring throw BeanCurrentlyInCreationException for a circular dependency?
The container cannot construct a dependency cycle safely, especially when both beans require constructor injection.
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Bean A needs B while B needs A, so neither constructor can complete first. Treat the exception as an ownership/design signal: extract the shared responsibility, invert a dependency, or communicate through an event. Lazy lookup can defer resolution but does not remove the cycle or its coupling.