Context-Aware Operations Skill

This skill provides patterns and techniques for managing large files and command outputs efficiently, preventing context window exhaustion while maintaining effective problem-solving capabilities.

When to Use

• Before executing commands that might produce large output
• Before reading any file in the codebase
• When debugging issues that might involve large resources
• When searching through codebases
• When working with logs, build outputs, or data files

When Not to Use

• For trivially small, single-file edits where the overhead of checking file size slows down the workflow unnecessarily.
• When the user explicitly demands the full output of a specific file and context limits are known to be sufficient.
• For interactive terminal sessions where pagination tools (less, more) are natively handled by the user.

Common Pitfalls

• Blind Dumping: Running cat on a build log without checking its size, instantly blowing out the LLM's context window.
• Truncating Crucial Errors: Using head to sample a file when the actual error message resides at the very end of the stack trace (where tail was needed).
• Ignoring Binary Files: Attempting to read binary artifacts or minified JS without filtering, resulting in unreadable token noise.

Core Principle

Always check before you dump!

Never blindly dump large resources into your context. Always:

1. Check the size first
2. Use filtering if needed
3. Focus on relevant portions only

File Size Checking

Check Line Count

# Fast line count
wc -l filename.txt

# Line count without filename
wc -l < filename.txt

# Line count with human-readable file size
wc -l filename.txt && ls -lh filename.txt

Check File Size

# Human-readable size
ls -lh filename.txt

# Size in bytes (Linux)
stat -c%s filename.txt

# Size in bytes (macOS)
stat -f%z filename.txt

# Quick check if file is large
[ $(wc -l < filename.txt) -gt 500 ] && echo "Large file" || echo "Small file"

Filtered File Reading

Read Beginning and End

# First 50 lines
head -n 50 filename.txt

# Last 50 lines
tail -n 50 filename.txt

# Both ends with separator
head -n 30 filename.txt && echo "..." && tail -n 30 filename.txt

Read Specific Ranges

# Lines 100-200
sed -n '100,200p' filename.txt

# Around a specific line (line 150 ± 25 lines)
sed -n '125,175p' filename.txt

# Skip first N lines, show next M
tail -n +100 filename.txt | head -n 50

Search-Based Reading

# Find and show context
grep -n "pattern" filename.txt

# Show matching lines with 5 lines of context
grep -C 5 "pattern" filename.txt

# Show matching lines with line numbers
grep -n "pattern" filename.txt | head -20

# Count matches without showing content
grep -c "pattern" filename.txt

Command Output Filtering

Check Output Size First

# Count lines before showing
command | tee >(wc -l >&2) | head -20

# Or separately
output_lines=$(command | wc -l)
echo "Command produced $output_lines lines"
if [ $output_lines -gt 100 ]; then
  command | head -50
else
  command
fi

Filter Common Patterns

# Show only errors and warnings
command 2>&1 | grep -E "error|warn|fail" -i

# Show only specific log levels
command | grep -E "ERROR|WARN|FATAL"

# Exclude verbose/debug lines
command | grep -v -E "DEBUG|TRACE|INFO"

# Show unique errors only
command 2>&1 | grep -i error | sort -u

Paginate Large Output

# First page
command | head -n 50

# Show summary instead of full output
command | wc -l
command | head -20 && echo "... (showing first 20 lines)"
command | tail -20 && echo "... (showing last 20 lines)"

Smart File Viewing Strategy

Decision Tree

#!/bin/bash
FILE=$1

# Check if file exists
if [ ! -f "$FILE" ]; then
  echo "File not found: $FILE"
  exit 1
fi

# Get line count
LINES=$(wc -l < "$FILE")

# Decide how to show the file
if [ $LINES -le 100 ]; then
  # Small file - show all
  cat "$FILE"
elif [ $LINES -le 500 ]; then
  # Medium file - show with indicator
  cat "$FILE"
  echo "--- End of file ($LINES lines) ---"
elif [ $LINES -le 2000 ]; then
  # Large file - show beginning and end
  echo "--- First 50 lines of $LINES ---"
  head -n 50 "$FILE"
  echo "--- ... ---"
  echo "--- Last 50 lines ---"
  tail -n 50 "$FILE"
else
  # Very large file - show summary only
  echo "File has $LINES lines (too large to show)"
  echo "First 30 lines:"
  head -n 30 "$FILE"
  echo "---"
  echo "Last 30 lines:"
  tail -n 30 "$FILE"
  echo "---"
  echo "Use 'grep' to search for specific content"
fi

Working with Logs

Efficient Log Analysis

# Find errors in log
grep -i error logfile.log | head -20

# Show recent errors
tail -1000 logfile.log | grep -i error

# Count error types
grep -i error logfile.log | awk '{print $NF}' | sort | uniq -c | sort -rn

# Show errors with timestamps
grep -i error logfile.log | awk '{print $1, $2, $NF}' | head -20

# Find exceptions with context
grep -B 3 -A 10 "Exception" logfile.log | head -50

Log Sampling

# Show every Nth line (sample large log)
awk 'NR % 10 == 0' large.log | head -100

# Show random sample
shuf -n 50 large.log

# Show first occurrence of each unique error
grep -i error large.log | awk '!seen[$0]++' | head -20

Working with Code

Search Code Efficiently

# Find function definitions (Python example)
grep -n "^def " *.py

# Find class definitions with context
grep -A 5 "^class " *.py | head -50

# Find TODO/FIXME comments
grep -rn "TODO\|FIXME" --include="*.py" | head -20

# Count occurrences per file
grep -rc "pattern" . | grep -v ":0$" | sort -t: -k2 -rn

Browse Large Codebases

# List all Python files with line counts
find . -name "*.py" -exec wc -l {} + | sort -rn | head -20

# Find files containing pattern with size check
for f in $(grep -l "pattern" *.py); do
  lines=$(wc -l < "$f")
  echo "$f: $lines lines"
done

# Show structure without dumping content
find . -type f -name "*.py" | head -30
tree -L 3 --filesfirst 2>/dev/null || find . -type d | head -20

Context Window Budget Management

Track Usage Mentally

• Small files (<100 lines): ~100 tokens per file
• Medium files (100-500 lines): ~500 tokens per file
• Large files (500-2000 lines): Consider partial reading
• Very large files (>2000 lines): Never dump completely

Prioritization Strategy

1. Critical: Files directly related to the bug/feature
2. Important: Dependencies and related modules
3. Nice-to-have: Context and documentation
4. Skip: Tangentially related or very large files

When Context is Running Low

# Instead of full file, show:
# 1. File summary
wc -l filename && head -20 filename

# 2. Function/class list
grep -E "^(def|class|function|export)" filename

# 3. Specific section only
sed -n '/start_marker/,/end_marker/p' filename

# 4. Just the relevant function
awk '/^def target_function/,/^def [^t]/' filename.py

Advanced Techniques

Pipe Chains for Efficiency

# Find, filter, and limit in one go
find . -name "*.log" -exec grep -l "ERROR" {} \; | head -10

# Search multiple files, show unique results
grep -rh "pattern" . | sort -u | head -20

# Complex filtering in stages
cat large.txt | \
  grep -i "keyword" | \
  grep -v "noise" | \
  sort -u | \
  head -30

Binary Search for Large Files

# Find approximate location of pattern
total_lines=$(wc -l < large.txt)
middle=$((total_lines / 2))

# Check first half
head -n $middle large.txt | grep -q "pattern" && echo "In first half" || echo "In second half"

# Then narrow down further

Incremental Reading

# Read file in chunks
chunk_size=100
current=0
total=$(wc -l < file.txt)

# Read first chunk
sed -n "1,${chunk_size}p" file.txt

# If needed, read next chunk
current=$((current + chunk_size))
sed -n "${current},$((current + chunk_size))p" file.txt

What to Avoid

1. Don't: cat huge_file.log Do: head -100 huge_file.log && echo "... (showing first 100 of $(wc -l < huge_file.log) lines)"
2. Don't: npm install --verbose Do: npm install 2>&1 | grep -E "error|warn" -i || echo "Install successful"
3. Don't: git log Do: git log --oneline -20 or git log --oneline | head -20
4. Don't: docker logs container Do: docker logs --tail 100 container or docker logs container 2>&1 | grep -i error
5. Don't: ./run_tests.sh Do: ./run_tests.sh 2>&1 | tee >(wc -l >&2) | grep -E "fail|error|pass" -i | head -50

Remember

• Size matters: Always check before you dump
• Filter first: Use grep, head, tail, sed, awk
• Focus: Only show what's relevant to the current task
• Summarize: When in doubt, show a summary rather than everything
• Iterate: You can always come back for more details if needed

Related Skills

• shell: You MUST load this skill when handling shell commands with performance monitoring or timeouts.

Your context window is precious - use it wisely!