bash-expert

Deep analysis of bash scripts for security, performance, portability, and best practices compliance

Optimize bash scripts for performance, reducing execution time and resource usage

Create, review, or optimize bash/shell scripts following 2025 best practices and cross-platform standards

Generate production-ready bash script templates with modern patterns, error handling, and configurable features

Expert bash/shell scripting for modern (2025-2026) cross-platform automation, security-first practices, and Bash 5.3+. PROACTIVELY activate for: ANY bash/shell scripting task; Bash 5.3 features (${|} REPLY, BASH_TRAPSIG, associative arrays, nameref, shopt, mapfile); security (input validation, command-injection prevention, unquoted-expansion review, safe temp files, HISTFILE protection); ShellCheck v0.11.0 (SC2327/SC2328/SC2294/SC2295, ShellCheck-clean code); debugging (strict mode set -euo pipefail, set -x, PS4 tracing, trap DEBUG, CI failures); parallel processing (xargs -P, GNU parallel, background jobs, retries); cross-platform (Linux/macOS/Windows/containers, Git Bash, MSYS/MINGW, MSYS_NO_PATHCONV, CRLF fixes, portable patterns); CI/CD scripting (GitHub Actions, Azure DevOps, Kubernetes, Docker); cloud helpers (AWS CLI, Azure CLI); deployment automation (blue-green, canary, rollbacks, deploy.sh); process substitution and FIFOs; Google Shell Style Guide; POSIX.1-2024. Provides production-ready scripts.

Advanced bash array patterns including indexed and associative arrays, mapfile/readarray, slicing, and array manipulation (2025). PROACTIVELY activate for: (1) using bash arrays effectively, (2) reading file contents into an array via mapfile/readarray, (3) authoring associative arrays (declare -A), (4) iterating arrays safely under set -u, (5) deleting/inserting array elements, (6) joining and splitting arrays, (7) passing arrays to functions via nameref (declare -n), (8) array slicing and parameter expansion, (9) sorting and deduplicating arrays in pure bash. Provides: indexed and associative array reference, mapfile and readarray recipes, nameref-based pass-by-reference, slicing/expansion patterns, and gotchas for unset variables and word splitting.

Bash 5.3 new features and modern patterns (2025). PROACTIVELY activate for: (1) Bash 5.3 specific features (BASH_TRAPSIG, in-shell command substitution, ${|} REPLY syntax), (2) checking bash version compatibility, (3) migrating scripts to take advantage of 5.3 additions, (4) C23 conformance changes in bash 5.3, (5) new shopt and bind options, (6) trap handling improvements, (7) wait -p enhancements, (8) READLINE_ARGUMENT and history expansion changes. Provides: complete 5.3 feature reference, version-detection snippets, compatibility shims for older bash, migration recipes, and POSIX.1-2024 alignment notes.

Expert bash/shell scripting across environments where Bash is available (Linux, macOS, Git Bash on Windows, WSL, containers). This is a Bash-focused skill - it does not provide PowerShell parity; on Windows the target is the Bash interpreter (Git Bash / WSL), not native PowerShell. PROACTIVELY activate for: (1) ANY bash/shell script task, (2) System automation, (3) DevOps/CI/CD scripts, (4) Build/deployment automation, (5) Script review/debugging, (6) Converting commands to scripts. Provides: Google Shell Style Guide compliance, ShellCheck validation, Bash portability across Linux/macOS/WSL/Git Bash/containers, POSIX compliance, security hardening, error handling, performance optimization, testing with BATS, and production-ready patterns. Ensures professional-grade, secure, portable Bash scripts every time.

Comprehensive bash script debugging and troubleshooting techniques for 2025. PROACTIVELY activate for: (1) debugging a misbehaving bash script, (2) using set -x, set -e, set -u, set -o pipefail (strict mode), (3) customizing PS4 for richer trace output, (4) trap DEBUG, ERR, and EXIT for diagnostics, (5) bashdb and other interactive debuggers, (6) profiling slow scripts (timing, BASH_REMATCH overhead), (7) reproducing CI-only failures locally, (8) resolving unbound variable or command not found errors, (9) understanding subshell vs current-shell variable scope. Provides: strict-mode template, PS4 patterns, trap recipes for instrumentation, profiling techniques, and a step-by-step debugging playbook.

Modern DevOps and CI/CD bash automation patterns with containers and cloud (2025). PROACTIVELY activate for: (1) writing CI/CD scripts (GitHub Actions, GitLab CI, Azure DevOps), (2) container-aware shell scripting (detecting containers, Kubernetes pods), (3) cloud provider helpers (AWS CLI, Azure CLI, gcloud), (4) blue-green and canary deployments via bash, (5) writing idempotent rollback scripts, (6) integrating with Docker/Compose from bash, (7) cross-environment variable management, (8) build matrix orchestration. Provides: copy-pasteable CI snippets, container detection helpers, cloud CLI wrappers, deployment orchestration patterns, and idempotent rollback templates.