MT5 Log Reader
Read MetaTrader 5 log files directly to access Print() output from indicators, scripts, and expert advisors without requiring manual Experts pane inspection.
Self-Evolving Skill: This skill improves through use. If instructions are wrong, parameters drifted, or a workaround was needed — fix this file immediately, don't defer. Only update for real, reproducible issues.
Purpose
Implement "Option 3" dual logging pattern:
- Print() - MT5 log files (human-readable via Experts pane)
- CSV files - Structured data (programmatic analysis)
Claude Code can autonomously read both outputs without user intervention.
When to Use This Skill
Use this skill when:
- Validating MT5 indicator/script execution
- Checking compilation or runtime errors
- Analyzing Print() debug output
- Verifying unit test results (Test_PatternDetector, Test_ArrowManager)
- User mentions checking "Experts pane" manually
Log File Location
MT5 logs are stored at:
$MQL5_ROOT/Program Files/MetaTrader 5/MQL5/Logs/YYYYMMDD.logFile Format:
- Encoding: UTF-16LE (Little Endian)
- Structure: Tab-separated fields (timestamp, source, message)
- Size: Grows throughout day (typically 10-100KB)
Instructions
1. Construct today's log path
/usr/bin/env bash << 'SKILL_SCRIPT_EOF'
# Determine current date
TODAY=$(date +"%Y%m%d")
# Build absolute path
LOG_FILE="$MQL5_ROOT/Program Files/MetaTrader 5/MQL5/Logs/${TODAY}.log"
SKILL_SCRIPT_EOF2. Read the entire log file
Use Read tool:
- File path: Absolute path from step 1
- The file contains all Print() statements from MT5 indicators/scripts
- UTF-16LE encoding is automatically handled by Read tool
3. Search for specific content (optional)
Use Grep to filter entries:
Pattern: indicator name, "error", "test.*passed", etc.
Path: Log file path from step 1
Output mode: "content" with -n (line numbers)
Context: -A 5 for 5 lines after matches4. Analyze recent entries (optional)
Use Bash with tail for latest output:
tail -n 50 "$LOG_FILE"Common Validation Patterns
Check unit test results
Search for test pass/fail indicators:
Pattern: test.*passed|test.*failed|Tests Passed|Tests Failed|ALL TESTS PASSED
Output mode: content
Context: -B 2 -A 2Find compilation errors
Pattern: error|ERROR|warning|WARNING|failed to create
Output mode: content
Context: -A 3Monitor specific indicator
Pattern: CCI Rising Test|PatternDetector|ArrowManager
Output mode: content
Context: -A 2View initialization messages
Pattern: OnInit|initialization|Initialization complete|Phase \d+
Output mode: contentExamples
Example 1: Validate unit test completion
Input: User compiled Test_PatternDetector.mq5
Action:
1. Read today's log file
2. Grep for "Test.*PatternDetector|Tests Passed|Tests Failed"
3. Report results (e.g., "17 tests passed, 0 failed")
Output: Test status without user checking Experts paneExample 2: Check for runtime errors
Input: User reports indicator not working
Action:
1. Read today's log file
2. Grep for "ERROR|error|failed" with -A 3 context
3. Analyze error messages
Output: Specific error details and line numbersExample 3: Verify Phase 2 arrow creation
Input: User asks "did the test arrow get created?"
Action:
1. Read today's log file
2. Grep for "Phase 2|Test arrow created|Failed to create"
3. Check for success/failure messages
Output: Arrow creation status with timestampSecurity Considerations
- Log files may contain sensitive trading data (symbol names, account info)
- Restricted to Read, Bash, Grep tools only (no network access via WebFetch)
- Do not expose absolute paths unnecessarily in user-facing output
- Filter sensitive information when reporting results
- No file modification operations allowed
Integration with Dual Logging
This skill enables programmatic access to one half of the dual logging pattern:
- MT5 Log Files (this skill) - Human-readable Print() output
- CSV Files (CSVLogger.mqh) - Structured audit trails for validation
Both are accessible without user intervention:
- MT5 logs: Read via this skill
- CSV files: Read directly via Read tool or validate_export.py
Validation Checklist
When using this skill:
- Log file exists for today's date
- File size > 0 (not empty)
- Contains expected indicator/script output
- Timestamps match execution time
- Error messages (if any) are actionable
- Test results (if applicable) show pass/fail counts
References
- MT5 file locations:
docs/guides/MT5_FILE_LOCATIONS.md - Dual logging implementation:
docs/plans/cci-rising-pattern-marker.yamlPhase 3-4 - CSVLogger library:
Program Files/MetaTrader 5/MQL5/Indicators/Custom/Development/CCINeutrality/lib/CSVLogger.mqh
Troubleshooting
| Issue | Cause | Solution |
|---|---|---|
| Log file not found | Wrong date or path | Verify YYYYMMDD.log format and MQL5_ROOT env var |
| Empty log file | MT5 not running or no output | Ensure MT5 is running and Print() is being called |
| Encoding errors | UTF-16LE not handled | Read tool handles encoding automatically |
| Missing test results | Test not executed | Compile and run test script in MT5 first |
| Grep finds nothing | Wrong pattern | Use case-insensitive (-i) or broader pattern |
| Old log data | Log rotation | Each day creates new YYYYMMDD.log file |
| Path contains spaces | Unquoted path variable | Quote paths: "$LOG_FILE" |
| Sensitive data exposed | Trading info in logs | Filter sensitive fields when reporting to user |
Post-Execution Reflection
After this skill completes, check before closing:
- Did the command succeed? — If not, fix the instruction or error table that caused the failure.
- Did parameters or output change? — If the underlying tool's interface drifted, update Usage examples and Parameters table to match.
- Was a workaround needed? — If you had to improvise (different flags, extra steps), update this SKILL.md so the next invocation doesn't need the same workaround.
Only update if the issue is real and reproducible — not speculative.