write – write to a file descriptor Synopsis#include <unistd.h> ssize_t write(int fd, const void *buf, size_t count); Descriptionwrite() writes up to count bytes from the buffer starting at buf to the file referred to by the file descriptor fd. The number of bytes written may be less than count if, for example, there is insufficient…
read – read from a file descriptor Synopsis#include <unistd.h> ssize_t read(int fd, void *buf, size_t count);Descriptionread() attempts to read up to count bytes from file descriptor fd into the buffer starting at buf. On files that support seeking, the read operation commences at the file offset, and the file offset is incremented by the number…
cat – concatenate files and print on the standard output Synopsiscat [,OPTION/]… [,FILE/]… DescriptionConcatenate FILE(s) to standard output. With no FILE, or when FILE is -, read standard input. -A, –show-all equivalent to -vET -b, –number-nonblank number nonempty output lines, overrides -n -e equivalent to -vE -E, –show-ends display $ at end of each line…
stat, fstat, lstat, fstatat – get file status Synopsis#include <sys/types.h> #include <sys/stat.h> #include <unistd.h> int stat(const char *pathname, struct stat *statbuf); int fstat(int fd, struct stat *statbuf); int lstat(const char *pathname, struct stat *statbuf); #include <fcntl.h> /* Definition of AT_* constants */ #include <sys/stat.h> int fstatat(int dirfd, const char *pathname, struct stat *statbuf, int flags);Feature…
grep, egrep, fgrep, rgrep – print lines that match patterns Synopsisgrep [OPTION…] PATTERNS [FILE…] grep [OPTION…] -e PATTERNS … [FILE…] grep [OPTION…] -f PATTERN_FILE … [FILE…] Descriptiongrep searches for PATTERNS in each FILE. PATTERNS is one or more patterns separated by newline characters, and grep prints each line that matches a pattern. Typically PATTERNS should…
malloc, free, calloc, realloc, reallocarray – allocate and free dynamic memory Synopsis#include <stdlib.h> void *malloc(size_t size); void free(void *ptr); void *calloc(size_t nmemb, size_t size); void *realloc(void *ptr, size_t size); void *reallocarray(void *ptr, size_t nmemb, size_t size);Feature Test Macro Requirements for glibc (see feature_test_macros(7)): reallocarray(): Since glibc 2.29: _DEFAULT_SOURCE Glibc 2.28 and earlier: _GNU_SOURCE DescriptionThe malloc()…
printf, fprintf, dprintf, sprintf, snprintf, vprintf, vfprintf, vdprintf, vsprintf, vsnprintf – formatted output conversion Synopsis#include <stdio.h> int printf(const char *format, …); int fprintf(FILE *stream, const char *format, …); int dprintf(int fd, const char *format, …); int sprintf(char *str, const char *format, …); int snprintf(char *str, size_t size, const char *format, …); #include <stdarg.h> int vprintf(const…
open, openat, creat – open and possibly create a file Synopsis#include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> int open(const char *pathname, int flags); int open(const char *pathname, int flags, mode_t mode); int creat(const char *pathname, mode_t mode); int openat(int dirfd, const char *pathname, int flags); int openat(int dirfd, const char *pathname, int flags, mode_t mode); /*…
ls – list directory contents Synopsisls [,OPTION/]… [,FILE/]… DescriptionList information about the FILEs (the current directory by default). Sort entries alphabetically if none of -cftuvSUX nor –sort is specified. Mandatory arguments to long options are mandatory for short options too. -a, –all do not ignore entries starting with . -A, –almost-all do not list implied…
Managing a large technical blog with over 1,300 posts presents real challenges. I want to share my experience using OpenClaw and Large Language Models (LLMs) to transform systutorials.com from a chaotic archive into a well-organized learning platform. The Problem I Faced Systutorials.com had accumulated 1,383 posts over years, but the organization was a mess. Visitors…
When running multiple OpenClaw agents on the same Telegram group, you can use Telegram’s topic feature to enable agent isolation. This guide explains the actual setup used for Eric’s OpenClaw group with multi-agent support. The Setup The configuration uses Telegram topics to isolate different agents so they don’t interfere with each other. Each agent works…
Running a blog for over a decade means accumulating a lot of technical debt. Commands change, tools get deprecated, Python 2 becomes Python 3, and posts that were accurate in 2013 start quietly misleading readers in 2026. For systutorials.com, that meant roughly 1,375 posts needed attention — some desperately. Doing that manually would take months….
For months, I’ve been running OpenClaw — a personal AI assistant integrated with Telegram that monitors my crypto portfolio and handles daily tasks. Initially, I used Anthropic’s Claude Sonnet, but the recurring costs add up fast for a 24/7 agent. OpenRouter’s free tier provides access to capable open-source models like Qwen and Llama at zero…
A crypto option gives you the right — but not the obligation — to buy or sell a cryptocurrency at a fixed price before a set date. Unlike a futures contract, where you’re locked in, an option lets you walk away if the trade goes against you. Your downside is capped at the premium you…
Crypto futures are contracts to buy or sell an asset at a predetermined price on a specific expiry date. They function similarly to traditional financial futures but operate within crypto markets. Key characteristics: Expiry dates: Set end dates, typically weekly, quarterly, or annual contracts Price convergence: As expiry approaches, the futures price converges with the…
Trading across decentralized exchanges requires navigating fragmented liquidity spread across dozens of protocols and blockchains. DEX aggregators and routers are the essential infrastructure that finds optimal execution paths, minimizes slippage, and protects against MEV extraction. Routers vs. Aggregators The distinction matters operationally: Routers are smart contracts that execute the actual trade logic. They determine the…
Cryptocurrency is a digital currency secured through cryptography and typically operating on decentralized blockchain networks. Unlike government-issued fiat currencies, cryptocurrencies derive their security and validation from distributed consensus mechanisms rather than central authorities. From Speculation to Real-World Infrastructure Early cryptocurrency adoption was primarily speculative. By 2026, the market has matured into genuine utility across multiple…
In decentralized networks like Bitcoin and Ethereum, temporary forks are an inevitable part of consensus. They happen when two miners or validators produce valid blocks at nearly the same time. The sequence looks like this: Simultaneous Discovery: Miner A and Miner B both find a valid Block 100 independently Network Propagation: Some nodes receive Miner…
The Trusted Platform Module (TPM) 2.0 is a cryptographic coprocessor—either as discrete hardware or firmware—that provides hardware-rooted security. It’s the foundation for features like Windows Hello, BitLocker, macOS FileVault, and Linux dm-crypt integration with hardware key binding. On modern systems, TPM 2.0 is nearly universal: integrated into recent Intel (PTT), AMD (fTPM), and ARM processors,…
Private key sharding splits a private key into multiple parts called “shards” that must be combined to reconstruct the original key. This eliminates the single point of failure inherent in traditional seed phrase storage while maintaining on-chain simplicity. The most common implementation uses Shamir’s Secret Sharing (SSS), a cryptographic scheme that guarantees security even if…