tomevault-io Log Analyzer
Overview
Parse, filter, and analyze system and application logs to find relevant entries, correlate events, and identify root causes. Handles multiple log formats across platforms.
Process
Step 1: Identify Log Sources
Determine what logs are relevant based on the user's issue:
System logs:
| Platform | Location | Command to read |
|---|---|---|
| Windows | Event Log | Get-EventLog -LogName [System|Application|Security] -Newest [N] |
| Windows | Modern | Get-WinEvent -LogName [name] -MaxEvents [N] |
| Linux | journald | journalctl [flags] |
| Linux | syslog | /var/log/syslog or /var/log/messages |
| macOS | Unified log | log show [flags] |
Application logs (common locations):
| Application | Typical Location |
|---|---|
| Nginx | /var/log/nginx/error.log, /var/log/nginx/access.log |
| Apache | /var/log/apache2/error.log, /var/log/httpd/error_log |
| Docker | docker logs [container] |
| Node.js | pm2 logs or custom path |
| PostgreSQL | /var/log/postgresql/ |
| MySQL | /var/log/mysql/error.log |
| IIS | C:\inetpub\logs\LogFiles\ |
Step 2: Define Search Parameters
Establish the investigation window:
- Time range: When did the issue start? Default to last 1 hour if unknown.
- Severity: errors only, warnings+errors, or all
- Keywords: error messages, service names, user IDs
- Correlation ID: trace IDs, request IDs, session IDs
Step 3: Extract and Filter
Use appropriate commands to pull relevant entries:
Time-based filtering:
| Platform | Command |
|---|---|
| Windows | Get-EventLog -LogName System -After (Get-Date).AddHours(-1) -EntryType Error |
| Linux | journalctl --since "1 hour ago" -p err --no-pager |
| macOS | log show --last 1h --predicate 'messageType == error' |
Keyword search in log files:
| Platform | Command |
|---|---|
| All | grep -i "[keyword]" [logfile] | tail -50 |
| Windows | Select-String -Path [file] -Pattern "[keyword]" -Context 2 |
Structured log parsing (JSON):
| Tool | Command |
|---|---|
| jq | cat [file] | jq 'select(.level == "error")' |
| grep+jq | grep "error" [file] | jq . |
Step 4: Analyze Patterns
Look for these common patterns:
| Pattern | Indicator | Likely Cause |
|---|---|---|
| Repeated error same timestamp | Burst of identical errors | Triggered by single event |
| Gradual increase in errors | Error count growing over time | Resource exhaustion |
| Periodic errors | Errors at regular intervals | Cron job or scheduled task |
| Error after deploy/update | Errors start at specific time | Code or config change |
| Cascading services | Multiple services error sequentially | Dependency failure |
| OOM / memory errors | "killed", "out of memory" | Memory leak or under-provisioned |
| Connection refused | "ECONNREFUSED", "connection reset" | Service down or port blocked |
| Permission denied | "EACCES", "403", "permission denied" | Permissions or auth issue |
Step 5: Correlate Events
Build a timeline of events:
### Event Timeline
| Time | Source | Event | Severity |
|------|--------|-------|----------|
| HH:MM:SS | [source] | [event] | [sev] |
| HH:MM:SS | [source] | [event] | [sev] |
### Correlation
- First error: [timestamp] in [source]
- Likely trigger: [what happened just before]
- Affected components: [list]
- Pattern: [burst/gradual/periodic]
Step 6: Present Findings
## Log Analysis Report
### Summary
- **Time window:** [start] to [end]
- **Total errors found:** [N]
- **Unique error types:** [N]
- **Most frequent:** [error message] ([count] occurrences)
### Root Cause Analysis
[What the logs indicate happened]
### Key Log Entries
[Show the 3-5 most relevant entries with context]
### Recommendations
1. [Immediate action]
2. [Preventive measure]
3. [Monitoring suggestion]
Rules
- NEVER read logs that might contain secrets (avoid printing full auth tokens, passwords)
- Truncate long log entries to relevant portions
- If log files are very large, use
tailor time filters first - ALWAYS show the user which files/sources you're reading
- If no relevant logs found, suggest where else to look
- Redact sensitive data (IPs, emails, tokens) in report output when sharing
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