Agent Skills: Modern CLI Tools

Modern CLI Tools

Use faster, ergonomic command-line tools installed on this system. Pick the tool by target, not habit. Habit is how grep -R survives.

Quick Reference

• Search code structure — ast-grep / sg (vs grep): AST-aware patterns, language constructs, safer refactor candidate search.
• Search text — rg (vs grep): fast literal/regex search, respects .gitignore.
• Find files — fd (vs find): simpler syntax, ignores .git.
• View files — bat (vs cat): syntax highlighting, line numbers.
• List files — eza (vs ls): icons, git status, tree view.
• Replace text — sd (vs sed): intuitive regex, preview mode.
• Disk usage — dust (vs du): visual tree, sorted by size.
• Processes — procs (vs ps): tree view, sortable columns.
• Diff files — delta (vs diff): syntax highlighting, side-by-side.

Search Decision Tree

1. Code shape or language construct? Use ast-grep / sg.
2. Exact text, docs, logs, comments, config keys? Use rg.
3. File or directory names? Use fd.
4. Legacy grep / find only if the modern tool is missing.

Examples

# Structural code search: ast-grep before rg
ast-grep run --pattern 'console.log($$$)' --lang javascript .
ast-grep run --pattern 'func $NAME($$$) { $$$ }' --lang go .
ast-grep scan --inline-rules 'id: await-in-func
language: javascript
rule:
  kind: function_declaration
  has:
    pattern: await $EXPR
    stopBy: end
' .

# Text search: rg instead of grep
rg "TODO" --type go           # Search Go files
rg -A 3 "error"               # 3 lines after match
rg -l "import"                # List files only

# Find files: fd instead of find
fd "\.go$"                    # Find Go files
fd -e json src/               # By extension in src/
fd -x wc -l {}                # Execute on matches

# View: bat instead of cat
bat main.go                   # With syntax highlighting
bat -n file.py                # Line numbers only

# List: eza instead of ls
eza -la --git                 # Long format with git status
eza --tree -L 2               # Tree view, 2 levels

# Replace: sd instead of sed
sd "old" "new" file.txt       # Simple replacement
sd -p "pattern" "new" file    # Preview changes first
sd -p 'colour' 'color' docs/**/*.md  # Preview only; do not apply without explicit ask

# Disk: dust instead of du
dust -d 2                     # 2 levels deep

# Processes: procs instead of ps
procs --tree                  # Process tree

Rules

• For code-structure searches, try ast-grep before rg. Examples: function declarations, call expressions, code inside methods, missing error handling, framework usage patterns.
• For plain text, docs, logs, and config keys, use rg; ast-grep is the wrong hammer.
• For file discovery, use fd before find.
• For preview-only replacement tasks, use sd -p and state it is preview-only. Do not emit a non-preview sd command unless the user explicitly asked to apply.
• If a modern tool is not on PATH, fall back to the legacy equivalent and note the fallback.
• Do not install missing tools silently; report what is missing and suggest the relevant install command.

Install Hints

brew install ast-grep ripgrep fd bat eza sd dust procs git-delta
npm install -g @ast-grep/cli
cargo install ast-grep

Productivity Tools

# Fuzzy finder
vim $(fd . | fzf)
rg "pattern" | fzf

# Benchmarking
hyperfine "rg pattern" "grep -r pattern"

# Code statistics
tokei .

# Markdown preview
glow README.md

# JSON/YAML processing
jq '.key' file.json
yq '.key' file.yaml