shell-mastery

name

shell-mastery

description

Expert shell configuration, optimization, and automation for Bash, Zsh, and PowerShell. Use when optimizing shell startup times, profiling performance bottlenecks, implementing defensive scripting patterns, configuring modern CLI tools (fzf, tmux, Atuin), writing portable POSIX scripts, engineering Zsh interactive environments, implementing PowerShell parallel execution, or troubleshooting shell performance issues. Applies to shell configuration files (.bashrc, .zshrc, PowerShell profiles), automation scripts, and terminal productivity workflows.

Optimize shell configurations and scripts to meet strict performance and defensive targets.

Shell Selection & Performance

Use Case	Shell	Key Choice Reason
System Automation	Bash	Universal container/VM compatibility
Interactive Dev	Zsh	Native macOS shell, rich completions
Windows/Cloud	PowerShell	Object pipeline, native .NET APIs

• Interactive Startup Target: 0.1s - 0.5s. Profile slow shells with Zsh zprof or PowerShell Measure-Command.
• Fuzzy Search Latency: <50ms using fzf or Atuin.

## Core Scripting & Config Snippets

1. Defensive Bash (Fail-Fast)

#!/bin/bash
set -euo pipefail
trap cleanup EXIT INT TERM
cleanup() { rm -f "$TEMP_FILE"; }

2. Portable Argument Parsing (POSIX)

while [ $# -gt 0 ]; do
    case "$1" in
        -h|--help) show_help; exit 0 ;;
        -v|--verbose) VERBOSE=1 ;;
        *) echo "Unknown option: $1" >&2; exit 1 ;;
    esac
    shift
done

3. Zsh Lazy-Loading & Async Plugins

# Lazy-load NVM
nvm() { unset -f nvm node npm; [ -s "$NVM_DIR/nvm.sh" ] && . "$NVM_DIR/nvm.sh"; nvm "$@"; }

# Async plugins via Zinit
zinit ice wait lucid
zinit light zsh-users/zsh-autosuggestions

4. PowerShell Parallelism

1..100 | ForEach-Object -Parallel { # Parallel work } -ThrottleLimit 10

## Deep-Dive Reference Manuals

• Read performance-optimization.md to diagnose slow shells, lazy-load SDKs, or profile startup latency.
• Read defensive-scripting.md when writing production scripts requiring signal traps, file locking, or strict error checking.
• Read portability.md to rewrite Bashisms into POSIX-compliant syntax for Alpine/minimal containers.
• Read modern-toolkit.md to configure fzf, tmux, Atuin, ripgrep, bat, or eza aliases.
• Read zsh-optimization.md to customize ZLE widgets, completion styles, or advanced glob qualifiers.
• Read powershell-patterns.md for object-oriented pipelines, ThreadJobs, and secure credential handling.

- Scripts MUST use defensive patterns (`set -euo pipefail`) to fail fast. - Non-critical plugins and SDK initializers (e.g. NVM, Conda) SHOULD be lazy-loaded. - Always verify shell compatibility (POSIX vs Bash/Zsh specific features) before execution.