sed

Files

SKILL.mdagentsreferencesscripts

Install

Install only this skill with npx skills

npx skills add alisonaquinas/llm-shared-skills --skill 'sed' -g -y

Install the containing skill bundle

/plugin install shared-skills@llm-skills

Download sed-skill.zip

This skill is bundled inside shared-skills. Use npx skills when you only want this skill, or install the bundle once to make every included skill available through the plugin marketplace flow. Browse the full skill bundle repository at github.com/alisonaquinas/llm-shared-skills.

Invoke

Invoke this skill after installation

/shared-skills:sed

SKILL.md

name: sed description: Transform text streams with sed for line filtering, global substitutions, and in-place file edits. Use when the agent needs to search-and-replace with regex, filter specific line ranges, delete patterns, or apply repeatable text transformations.

Stream editor for deterministic, line-oriented text transformation and filtering.

Quick Start

Verify sed is available: sed --version or man sed
Establish the command surface: man sed or sed --help
Start with a read-only probe: sed 's/old/new/' file.txt

Intent Router

Load only the reference file needed for the active request.

references/install-and-setup.md — Installing sed (GNU, BSD) on macOS, Linux, Windows
references/cheatsheet.md — Common flags, substitution, line selection, deletion, extended regex
references/advanced-usage.md — Multi-line patterns, address ranges, branching, hold space, GNU vs BSD differences
references/troubleshooting.md — Regex escaping, in-place edit failures, performance, encoding issues

Core Workflow

Verify sed variant (GNU vs BSD): sed --version or man sed
Test on sample data first (never on production): sed 's/old/new/' sample.txt
Use -n (quiet) with explicit p commands to prevent double-printing
Use -i.bak (with backup suffix) for in-place edits to allow rollback
Quote scripts carefully to avoid shell interpretation

Quick Command Reference

sed --version                           # Check version (GNU vs BSD)
sed 's/old/new/' file.txt              # Replace first match per line
sed 's/old/new/g' file.txt             # Replace all matches per line
sed -n '10,20p' file.txt               # Print lines 10-20 only
sed -n '/pattern/p' file.txt           # Print lines matching pattern
sed '/pattern/d' file.txt              # Delete lines matching pattern
sed -i.bak 's/old/new/g' file.txt      # In-place edit with backup
sed -e 's/a/b/' -e 's/c/d/' file.txt   # Multiple scripts
sed 'N;s/\n/ /' file.txt               # Join consecutive lines
man sed                                 # Full manual and options

Safety Notes

Area	Guardrail
Regex escaping	Special characters (/, , &, $) in patterns/replacements require careful escaping. Use -E for extended regex. Test on sample data.
In-place edits	Always use `-i.bak` (with backup suffix), never `-i` alone. Allows easy rollback if command is incorrect.
Double-printing	With `-n` flag, only requested lines print. Without `-n`, all lines print by default (may duplicate matches).
GNU vs BSD	Flag syntax differs (`-i.bak` vs `-i.bak` spacing, -E vs -r for extended regex). Test cross-platform or specify variant.
Performance	Complex multi-line patterns using hold space can be slow on large files. Use line-oriented tools (grep, awk) when possible.
Encoding	sed may corrupt multi-byte UTF-8 if patterns split characters. Test with actual data; consider iconv preprocessing.

Source Policy

Treat the installed sed behavior and man sed as runtime truth.
Use GNU sed documentation (gnu.org/software/sed) for GNU-specific extensions.
Use BSD sed manual for BSD variant behavior differences.

Resource Index

scripts/install.sh — Install sed (GNU sed or BSD sed) on macOS or Linux.
scripts/install.ps1 — Install sed on Windows or any platform via PowerShell.