Files

SKILL.mdagentsreferencesscripts

Install

Install the containing plugin

/plugin install shared-skills@llm-skills

Invoke this skill after installation

/shared-skills:sed

Download sed-skill.zip

This skill is bundled inside shared-skills. Install the plugin once, then Claude Code can use any of its included skills. Browse the full plugin repository at github.com/alisonaquinas/llm-shared-skills.

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.

sed

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.