Each process on Linux has its own environment variable namespace. While normally isolated, there are scenarios where you might need to modify a running process’s environment—usually for debugging, testing, or dynamic configuration changes. The standard approach uses GDB’s ability to call functions within a running process. This works by attaching GDB to the target process…
Hyperledger Fabric is a modular, enterprise-grade consortium blockchain platform. While its official documentation is comprehensive, deploying a test network from scratch requires configuring multiple dependencies and tools—a process that’s time-consuming for new users. This guide covers both automated and manual setup approaches to get a working Fabric network running quickly. Prerequisites You’ll need: Ubuntu 24.04…
GCC applies sophisticated optimizations to recursive functions, and recursive inlining is one of the most dramatic. When the compiler can’t use simple tail-call optimization—because a function has side effects like printf that reference stack parameters—it often unrolls multiple recursion iterations into a single function body. Understanding this behavior matters for performance tuning, debugging, and predicting…
The built-in pdb module is Python’s equivalent to gdb — a command-line debugger that lets you step through code, set breakpoints, inspect variables, and control execution flow. It’s essential for server-side debugging and situations where IDE graphical debuggers aren’t available. Starting a pdb Session Run a script through pdb directly: python -m pdb prog.py arg1…
When managing packages on RHEL, CentOS, AlmaLinux, or Fedora, you sometimes need to prevent a package from being installed or updated from a particular repository. This is useful when multiple repos provide the same package and you want to control which version gets pulled in. Repository-specific exclusions with DNF Modern systems use DNF (which supersedes…
You can pause and resume any process on Linux using signals without stopping it completely. This is useful for managing resource-heavy jobs, debugging, or controlling execution flow without losing process state. Using SIGSTOP and SIGCONT The standard approach uses two signals: SIGSTOP: Pauses a process (cannot be caught or ignored) SIGCONT: Resumes a paused process…
To generate native assembly code (x86-64 asm, ARM64, etc.) from OCaml’s native compiler, use the -S flag along with other optimization-related options: ocamlopt -S -inline 20 -nodynlink not.ml -o not.opt This produces a .s file containing the generated assembly. The flags break down as: -S — Stop after assembly generation and keep the .s file…
The x86-64 architecture on Linux follows the System V AMD64 ABI calling convention. Understanding this is essential when writing assembly, optimizing code, debugging, or interfacing with C libraries. Register usage for arguments Integer and pointer arguments use these registers in order: RDI — first argument RSI — second argument RDX — third argument RCX —…
To enable debugging, configure your CMake build with CMAKE_BUILD_TYPE set to Debug. This tells CMake to invoke the compiler with the -g flag, generating debug symbols that tools like gdb and lldb need. From your project’s root directory: cmake -DCMAKE_BUILD_TYPE=Debug -B build cd build make The -B build flag creates a separate build directory, which…
Before writing code, get comfortable with fundamental Linux commands. You’ll use these daily: File operations: ls, cd, cat, less Text search: grep, ripgrep (rg) Remote access: ssh, scp, rsync Session management: tmux or screen for persistent terminal sessions Shell: bash (default on most distributions), though zsh and fish are popular alternatives Start with built-in documentation….
Static linking embeds all library code directly into your binary. On Linux, this sounds straightforward but glibc introduces complications that pure static binaries don’t truly exist — the C library still loads dynamic features at runtime like NSS (Name Service Switch), locale data, and character set converters. Understanding these constraints is essential before committing to…
cppreference.com is the authoritative resource for C++ language and standard library documentation. It covers all C++ standards from C++98 through C++26 with clear examples and cross-references. Bookmark it as your primary reference. The official C++ standard drafts are available through the C++ standards committee. While final standards require purchase, draft versions and proposals are freely…
Java eliminated pointers entirely in favor of automatic garbage collection. C++ gives you manual control through pointers and references, which provides performance benefits but introduces memory leak risks if misused. In Java, object references are automatically managed — you don’t allocate or free memory explicitly. The garbage collector runs periodically and reclaims unreachable objects. This…
Bash has no native floating point support. The (( )) and $(( )) arithmetic expansions only handle integers. For decimals, you need external tools — primarily bc, awk, or dc. bc: Arbitrary Precision Calculator bc is the standard choice for floating point math in shell scripts. It’s POSIX-compliant, available on every Unix-like system, and handles…
x86-64 (Intel 64, AMD64) is the dominant 64-bit instruction set architecture for consumer and enterprise computing. Whether you’re reverse-engineering binaries, writing performance-critical code, or understanding system internals, a solid grasp of x86-64 assembly is essential. Learning Foundations CMU’s Introduction to Computer Systems (15-213) course materials remain the gold standard for foundational machine-level programming. The accompanying…
GCC allows you to embed assembly code directly in C/C++ programs through inline assembly (asm and __asm__). This is useful when you need fine-grained control over processor execution—forcing variables into specific registers, reading CPU state efficiently, or hand-optimizing critical sections verified by profiling. Basic Syntax GCC uses AT&T syntax by default on x86/x86-64. The simplest…
GDB is the standard debugger for C/C++ development on Linux. This reference covers essential commands for breakpoints, execution control, inspection, and troubleshooting common debugging scenarios. Starting GDB gdb ./program gdb ./program core.dump # Debug with core file gdb -p <pid> # Attach to running process gdb –args ./program arg1 arg2 # Pass arguments to program…
cgdb is a curses-based frontend to gdb that keeps your source code visible while you debug. Unlike raw gdb, it splits the interface into two panes: source code on top, gdb command prompt below. If you’re already comfortable with Vim keybindings, cgdb feels natural—it uses the same navigation keys and modal editing paradigms you’re used…
When debugging and optimizing C/C++ programs, you need to see how the compiler translates your source code into assembly. A mixed source and assembly listing lets you trace exactly what machine instructions correspond to each line of your source. Using objdump (Recommended Modern Approach) The most straightforward method is to compile with debugging symbols and…
Use std::hex to format output as hexadecimal. This manipulator sets the basefield of the stream, affecting all subsequent integer output until you change it. #include <iostream> int main() { int x = 255; std::cout << “x in hexadecimal: ” << std::hex << x << std::endl; return 0; } Output: x in hexadecimal: ff By default,…