When your system slows to a crawl, top and htop show you exactly who's responsible—which processes are devouring CPU, hoarding memory, and waiting on stuck I/O.
Every Linux system keeps a detailed diary of everything that happens—kernel panics, login attempts, service crashes. Here's how to read it.
Logs are time frozen into text. The -f flag unfreezes them—turning static files into live streams of system activity as it happens.
grep turns thousands of log lines into answers. Learn to interrogate logs with patterns, context, and the detective mindset that transforms noise into signal.
Grep finds lines. Awk understands them—splitting each into fields, counting patterns across millions of entries, and answering questions grep can't even ask.
When something breaks, you need to find the relevant log entry among millions. journalctl turns that haystack into a database you can query by time, service, and severity.
When your system slows down, vmstat tells you where time is going while iostat reveals what the disks are doing. Together they triangulate bottlenecks that neither tool can find alone.
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