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.

Purpose

Implement "Option 3" dual logging pattern:

• Print() - MT5 log files (human-readable via Experts pane)

• CSV files - Structured data (programmatic analysis)

Claude Code CLI 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.log

File 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_EOF

2. 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 matches

4. 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 2

Find compilation errors

Pattern: error|ERROR|warning|WARNING|failed to create Output mode: content Context: -A 3

Monitor specific indicator

Pattern: CCI Rising Test|PatternDetector|ArrowManager Output mode: content Context: -A 2

View initialization messages

Pattern: OnInit|initialization|Initialization complete|Phase \d+ Output mode: content

Examples

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 pane

Example 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 numbers

Example 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 timestamp

Security 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.yaml Phase 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