System Calls Fundamentals Questions

Core OS-level concepts covering system call interfaces and conventions, examples such as fork, exec, opendir, and stat, kernel-user space interactions, process lifecycle, file I/O, memory management primitives, and basic concurrency primitives in systems programming.

MediumTechnical

52 practiced

Explain how inotify(7) can be used to watch configuration files and directories for changes and trigger reloads in a service. Describe the resource limits (inotify max_user_watches), race conditions (e.g., moved/renamed files), and alternatives such as fanotify or eBPF-based watchers for large-scale monitoring with lower overhead.

MediumTechnical

103 practiced

Explain the semantics of O_APPEND on Linux. Is write(2) atomic for multiple processes appending to the same file? Under what conditions does the kernel guarantee atomicity for appends, and what are the implications for multi-process logging? Provide recommendations for safe concurrent appends.

MediumTechnical

63 practiced

Describe differences between fork(2), vfork(2), and clone(2) on Linux. Explain copy-on-write semantics after fork, behavioral/performance differences for vfork, and how clone allows thread-like or namespace behavior. For each primitive, give SRE-relevant use cases and hazards (e.g., memory doubling, deadlocks, container namespace creation).

HardSystem Design

61 practiced

Design a kernel/user-space cooperative backpressure mechanism for a high-throughput message queue that can suffer syscall storms and resource exhaustion. Describe how to apply backpressure early (e.g., accept/recv throttling), use cgroups to limit CPU/IO, and how user-space components should surface health signals for orchestrators to scale or throttle. Discuss fairness, per-client limits, and metrics to monitor.

EasyTechnical

57 practiced

Explain differences between stat(2), fstat(2), and lstat(2). Provide examples of when each should be used, how they behave with symbolic links, and how to robustly detect whether a path refers to a regular file, directory, or symlink. Include SRE considerations around TOCTOU when relying on stat information.

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