Grep and Read Skill

Purpose: Search for pattern and read all matching files in a single coordinated operation, eliminating sequential round-trips.

Performance: 50-70% time savings, 4000-8000 token savings compared to sequential Grep -> Read -> Read -> Read pattern.

When to Use:

• Exploring codebase for specific functionality
• Finding all files containing a pattern
• Researching implementation approaches
• Investigating errors or bugs across multiple files

Anti-Pattern This Skill Replaces

INEFFICIENT PATTERN (4 messages, 9-12 seconds):

Message 1: Grep "FormattingRule" -> returns 5 files
  [Wait for response ~2.5s]

Message 2: Read src/main/java/.../FormattingRule.java
  [Wait for response ~2.5s]

Message 3: Read src/test/java/.../FormattingRuleTest.java
  [Wait for response ~2.5s]

Message 4: Read docs/architecture.md
  [Wait for response ~2.5s]

-> Impact: 4 round-trips = ~10 seconds, ~12,000 tokens
-> Wasted: 3 avoidable round-trips

EFFICIENT PATTERN (1 message, 3-4 seconds):

Message 1: Skill grep-and-read pattern="FormattingRule" max_files=5
  - Grep finds matches
  - Read all matching files in parallel
  - Return consolidated output
  [Wait for response ~3.5s]

-> Impact: 1 round-trip = ~3.5 seconds, ~4,000 tokens
-> Saved: 3 round-trips = 6.5 seconds (65% faster), 8,000 tokens

Skill Parameters

Skill Workflow

Step 1: Search for Pattern

Use Grep tool to find all files containing the pattern:

# Search for pattern with optional filters
Grep: pattern="{pattern}"
  path="{path}"
  glob="{glob}"
  output_mode="files_with_matches"
  -i={!case_sensitive}

Example:

Grep: pattern="FormattingRule"
  path="/path/to/project"
  glob="*.java"
  output_mode="files_with_matches"

Output: List of file paths

src/main/java/io/github/cowwoc/styler/formatter/FormattingRule.java
src/main/java/io/github/cowwoc/styler/formatter/FormattingRuleImpl.java
src/test/java/io/github/cowwoc/styler/formatter/FormattingRuleTest.java

Step 2: Read All Matching Files (Parallel)

Read all found files in a single message using multiple Read tool calls:

# Parallel read invocations in one message
Read: /path/to/project/src/main/java/.../FormattingRule.java
Read: /path/to/project/src/main/java/.../FormattingRuleImpl.java
Read: /path/to/project/src/test/java/.../FormattingRuleTest.java

If max_files exceeded: Show first N files, report total found If context_lines limited: Read first N lines of each file

Step 3: Consolidate and Report

Provide summary and consolidated output:

===============================================================
GREP AND READ SUMMARY
===============================================================
Pattern:        FormattingRule
Files Found:    3
Files Read:     3
Total Size:     ~15KB
Time Saved:     ~6.5 seconds (vs sequential)
Tokens Saved:   ~8,000 tokens
===============================================================

FILES READ:

---------------------------------------------------------------
FILE 1: src/main/java/.../FormattingRule.java
---------------------------------------------------------------
[file contents...]

---------------------------------------------------------------
FILE 2: src/main/java/.../FormattingRuleImpl.java
---------------------------------------------------------------
[file contents...]

---------------------------------------------------------------
FILE 3: src/test/java/.../FormattingRuleTest.java
---------------------------------------------------------------
[file contents...]

Usage Examples

Example 1: Explore API Implementation

Goal: Understand how "FormattingRule" is implemented

Command:

Skill: grep-and-read
  pattern="FormattingRule"
  path="/path/to/project"
  glob="*.java"
  max_files=5

Benefit: Get complete picture of implementation in one round-trip

Example 2: Research Error Handling

Goal: Find all files handling "ValidationException"

Command:

Skill: grep-and-read
  pattern="ValidationException"
  path="/path/to/project/src"
  max_files=10
  context_lines=50

Benefit: See all error handling patterns without multiple reads

Example 3: Documentation Research

Goal: Find all documentation mentioning "error handling"

Command:

Skill: grep-and-read
  pattern="error handling"
  path="/path/to/project/docs"
  glob="*.md"
  case_sensitive=false
  context_lines=0

Benefit: Read all relevant docs in one operation

Example 4: Test Coverage Analysis

Goal: Find all tests for "Formatter" classes

Command:

Skill: grep-and-read
  pattern="class.*Formatter.*Test"
  path="/path/to/project/src/test"
  glob="*Test.java"
  max_files=8

Benefit: See complete test coverage at once

Edge Cases

Too Many Matches

Problem: Pattern matches 50+ files

Solution:

1. Report total matches found
2. Read first max_files only
3. Suggest more specific pattern or glob filter

Output:

Warning: Pattern matched 53 files
Reading first 5 files (use max_files parameter to adjust)
Suggestion: Refine pattern or add glob filter for more targeted search

Large Files

Problem: Files exceed context window

Solution:

1. Use context_lines parameter to limit output
2. Read first N lines of each file
3. Report truncation with file statistics

Output:

File: FormattingRule.java
   Total lines: 1500
   Read lines: 100 (first 100)
   [... file contents ...]
   [... truncated: showing 100 of 1500 lines ...]

No Matches

Problem: Pattern doesn't match any files

Solution:

1. Report no matches found
2. Suggest alternative search strategies
3. Verify search path and pattern

Output:

No files found matching pattern: "FooBar"
Search path: /path/to/project
Suggestions:
   - Try case-insensitive search (case_sensitive=false)
   - Broaden pattern (use wildcards)
   - Check search path is correct

Performance Comparison

Scenario: Finding and reading 5 files

Scenario: Finding and reading 3 files

When to Use This Skill

Use Grep alone when:

• You need only file paths (use output_mode="files_with_matches")
• You need specific line context (use output_mode="content" and -C flag)
• Files are too large (> 1000 lines each) and you need to see matches before committing to full reads
• Pattern is exploratory and you want to evaluate matches first

Use this skill when:

• You know you'll read the matching files
• Files are reasonably sized (< 1000 lines each)
• You want comprehensive view of pattern usage
• Exploring codebase for implementation understanding

Integration with Existing Tools

Complements batch-read Skill

batch-read: Use when you KNOW which files to read

# You already know the files
batch-read: "error-handling" --type md --max-files 5

grep-and-read: Use when you need to FIND files first

# You need to discover the files
grep-and-read: pattern="error handling" glob="*.md"

Complements Grep Tool

Grep (content mode): Use for seeing match context

# See lines around matches
Grep: pattern="FormattingRule" output_mode="content" -C=3

grep-and-read: Use for reading entire matching files

# Read complete files
grep-and-read: pattern="FormattingRule" max_files=5

Related Skills:

• batch-read - Read known files in batch

Related Tools:

• Grep tool - Pattern search
• Read tool - File reading