https://jsokit.com/blog/tags/tutorial/ Recent content in Tutorial on JsonKit Blog Hugo en © 2025 JsonKit Fri, 08 May 2026 10:48:36 +0000 https://jsokit.com/blog/posts/unix-timestamp-pitfalls-a-complete-guide-to-timestamp-conversion/ Fri, 08 May 2026 10:48:36 +0000 https://jsokit.com/blog/posts/unix-timestamp-pitfalls-a-complete-guide-to-timestamp-conversion/ Unix Timestamp Pitfalls: A Complete Guide to Timestamp Conversion Last week, I was debugging a production issue. The logs were filled with numbers like 1745678901. Our new intern looked confused: “What are these?” I said, “Unix timestamps.” He asked, “How do I convert them to human-readable time?” That question made me realize timestamp conversion is trickier than I thought. What is a Unix Timestamp? A Unix timestamp is the number of seconds since January 1, 1970, 00:00:00 UTC. https://jsokit.com/blog/posts/from-manual-to-automated-systemd-service-unit-configuration-best-practices/ Mon, 04 May 2026 12:34:21 +0000 https://jsokit.com/blog/posts/from-manual-to-automated-systemd-service-unit-configuration-best-practices/ From Manual to Automated: Systemd Service Unit Configuration Best Practices Last week, while deploying a Node.js application to production, I hit another systemd pitfall. The service kept exiting silently with no error logs. After hours of debugging, I discovered the conflict between Type=simple and an incorrect ExecStop configuration. I decided to build a tool to codify all the lessons learned over the years. The Three-Section Structure of a Service Unit A standard . https://jsokit.com/blog/posts/redis-cheatsheet-implementation-from-data-structures-to-category-filtering/ Sun, 26 Apr 2026 16:29:59 +0000 https://jsokit.com/blog/posts/redis-cheatsheet-implementation-from-data-structures-to-category-filtering/ Redis Cheatsheet Implementation: From Data Structures to Category Filtering Our team recently added Redis to a new project. A few junior devs kept forgetting commands. The docs are too long, CLI help is too brief. So I built a cheatsheet tool and organized Redis data structures and command categories properly. Five Core Redis Data Structures Redis is fast not just because of in-memory storage, but because of its data structure design. https://jsokit.com/blog/posts/from-variable-extraction-to-smart-filling-building-a-prompt-template-manager/ Thu, 23 Apr 2026 11:37:47 +0000 https://jsokit.com/blog/posts/from-variable-extraction-to-smart-filling-building-a-prompt-template-manager/ From Variable Extraction to Smart Filling: Building a Prompt Template Manager Recently, while using AI tools like ChatGPT and Claude, I noticed many prompts are reusable. For scenarios like code review, bug fixing, and documentation generation, the prompt structure stays similar—only the parameters change. So I built a template management tool and documented the implementation approach. The Variable Extraction Algorithm The core question: how do we extract {{variable}} placeholders from text? https://jsokit.com/blog/posts/linux-xargs-command-deep-dive-bridging-pipes-and-command-arguments/ Sat, 11 Apr 2026 16:14:25 +0000 https://jsokit.com/blog/posts/linux-xargs-command-deep-dive-bridging-pipes-and-command-arguments/ Linux xargs Command Deep Dive: Bridging Pipes and Command Arguments If you’ve used Linux for a while, you’ve probably encountered this frustration: piping the output of one command to another, only to get an error. # Delete all .log files find . -name "*.log" | rm rm: missing operand The problem is that rm doesn’t accept standard input—it only takes command-line arguments. This is where xargs comes in. What xargs Actually Does xargs reads from standard input, converts it into command-line arguments, and passes them to another command. https://jsokit.com/blog/posts/linux-wc-command-more-than-just-counting-lines/ Thu, 09 Apr 2026 16:30:13 +0000 https://jsokit.com/blog/posts/linux-wc-command-more-than-just-counting-lines/ Linux wc Command: More Than Just Counting Lines When writing code, you often need to quickly check file stats. Counting lines, measuring code size, checking file sizes—wc handles all of this. Basic Usage wc stands for Word Count, but it does much more: # Count lines, words, and bytes wc file.txt # Output: 12 48 256 file.txt # lines words bytes # Individual counts wc -l file.txt # Lines only: 12 wc -w file. https://jsokit.com/blog/posts/linux-watch-command-deep-dive-from-real-time-monitoring-to-change-detection/ Thu, 09 Apr 2026 11:01:07 +0000 https://jsokit.com/blog/posts/linux-watch-command-deep-dive-from-real-time-monitoring-to-change-detection/ Linux watch Command Deep Dive: From Real-time Monitoring to Change Detection Time: 2026-05-11 16:57 Ever found yourself repeatedly running the same command—checking GPU usage, monitoring log file sizes, or waiting for a process to appear? Many developers manually execute commands over and over, unaware that Linux has a built-in gem: the watch command. Core Principles of watch At its core, watch is simple: loop execution + full-screen display. But the implementation details are worth exploring. https://jsokit.com/blog/posts/linux-vmstat-command-deep-dive-from-kernel-statistics-to-performance-bottleneck-diagnosis/ Wed, 08 Apr 2026 16:27:39 +0000 https://jsokit.com/blog/posts/linux-vmstat-command-deep-dive-from-kernel-statistics-to-performance-bottleneck-diagnosis/ Linux vmstat Command Deep Dive: From Kernel Statistics to Performance Bottleneck Diagnosis Published: May 11, 2026 10:08 When tuning Linux system performance, you’ve likely used top or htop. But when you need to dig into CPU scheduling, memory paging, and I/O wait times, vmstat is the real powerhouse. Born in 1983, this tool remains the go-to choice for sysadmins diagnosing performance bottlenecks. The Six Dimensions of vmstat Output Running vmstat directly gives you a table: https://jsokit.com/blog/posts/linux-uniq-command-from-adjacent-deduplication-to-count-statistics/ Tue, 07 Apr 2026 16:07:16 +0000 https://jsokit.com/blog/posts/linux-uniq-command-from-adjacent-deduplication-to-count-statistics/ Linux uniq Command: From Adjacent Deduplication to Count Statistics When processing log files or analyzing data, deduplication is a common task. The uniq command does exactly that—but with a catch: it only removes adjacent duplicate lines. Let’s dive deep into how uniq works and its practical applications. Core Algorithm: Adjacent Line Comparison The implementation of uniq is surprisingly simple—a state machine at its heart: // Simplified uniq core logic char *prev_line = NULL; while ((line = read_line()) ! https://jsokit.com/blog/posts/linux-tr-command-deep-dive-the-art-of-character-translation/ Mon, 06 Apr 2026 09:19:09 +0000 https://jsokit.com/blog/posts/linux-tr-command-deep-dive-the-art-of-character-translation/ Linux tr Command Deep Dive: The Art of Character Translation Exploring the most elegant character processing tool in Unix/Linux, from ASCII tables to stream processing internals Published: May 8, 2026 01:40 Introduction: The Philosophy of One Command tr is a perfect embodiment of the Unix philosophy—it does one thing, but does it exceptionally well. As the “character sculpting knife” in the Linux text processing toolkit, tr efficiently handles character translation, deletion, and squeezing operations.