Log Inspector

A Windows desktop application for parsing, viewing, and analyzing large log files

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✨ Features

• 🎯 Template-based parsing using regular expressions
• 🎨 Conditional row coloring based on column values
• 🔍 Advanced filtering with multiple criteria types (equality, contains, regex, comparison)
• ⚡ High performance with UI virtualization for handling millions of log entries
• 📝 Multi-line support for stack traces and extended messages
• 📊 Live file monitoring with read-only mode and file sharing
• 💾 XML template storage for easy reuse and sharing
• 🎭 Detail pane for viewing full log entry content

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🚀 Quick Start

Prerequisites

• Windows 10 or later
• .NET Core 8.0+
• Visual Studio 2022 or later (for development)

Installation

1. Build from source:

   git clone https://github.com/valentynblaha/LogInspector.git
   cd loginspector
   # Open LogInspector.sln in Visual Studio
   # Build and run (F5)

2. Or download the release:

   • Download the latest release from the Releases page
   • Extract and run LogInspector.exe

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📖 User Guide

1. Create a Template

Templates define how your log files are parsed. Each template contains:

• A regex pattern with capture groups for each column
• Column definitions (name, data type, format)
• Color rules for conditional formatting

Example: Creating a Template for Java Logs

Sample Log:

2025-10-08 02:35:33,028 DEBUG no-user [com.yourapp.security.LoginManager] Connection established

Steps:

1. Go to Template → New Template
2. Enter template name: "Java Application Log"
3. Enter regex pattern:

   ^(\d{4}-\d{2}-\d{2} \d{2}:\d{2}:\d{2},\d{3})\s+(\w+)\s+(\S+)\s+\[([^\]]+)\]\s+(.*)$

4. Add columns:
   • Timestamp (Date) - Format: yyyy-MM-dd HH:mm:ss,fff
   • Level (Enum)
   • User (String)
   • Class (String)
   • Message (String)
5. Add color rules:
   • Level = ERROR → #FFCCCC (red)
   • Level = WARN → #FFF4CC (yellow)
   • Level = INFO → #E6F3FF (blue)
   • Level = DEBUG → #F0F0F0 (gray)
6. Click OK

2. Save and Load Templates

• Save: Template → Save Template (creates an XML file)
• Load: Template → Load Template (loads existing XML)
• Edit: Template → Edit Current Template

3. Open a Log File

1. Load a template first
2. Go to File → Open Log File
3. Select your log file
4. The application parses and displays the logs automatically

4. Filter Logs

Apply filters to focus on specific entries:

1. Go to Filter → Add Filter
2. Select a column (e.g., "Level")
3. Choose an operator:
   • Equals - Exact match
   • NotEquals - Exclude specific values
   • Contains - Substring search
   • NotContains - Exclude substring
   • GreaterThan / LessThan - Numeric/date comparison
   • Regex - Pattern matching
4. Enter the value
5. Click OK

Example Filters:

• Show only errors: Level = ERROR
• Show recent logs: Timestamp > 2025-10-08
• Find specific user: User contains batch
• Complex pattern: Message regex (?i)exception|error

Multiple filters work together (AND logic).

5. View Details

Click any row to see the full log entry in the detail pane. This is especially useful for:

• Multi-line stack traces
• Long error messages
• Wrapped text

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🎨 Template Examples

Apache Access Log

Pattern:

^(\S+) \S+ \S+ \[([^\]]+)\] "(\w+) ([^"]+)" (\d{3}) (\d+)$

Columns:

• IP (String)
• Timestamp (Date) - dd/MMM/yyyy:HH:mm:ss zzz
• Method (Enum)
• URL (String)
• Status (Number)
• Bytes (Number)

Windows Event Log Export

Pattern:

^(\d{1,2}/\d{1,2}/\d{4} \d{1,2}:\d{2}:\d{2} [AP]M)\s+(\w+)\s+(\w+)\s+(.+)$

Columns:

• Timestamp (Date) - M/d/yyyy h:mm:ss tt
• Level (Enum)
• Source (String)
• Message (String)

Syslog Format

Pattern:

^(\w{3}\s+\d{1,2} \d{2}:\d{2}:\d{2}) (\S+) (\S+)\[(\d+)\]: (.+)$

Columns:

• Timestamp (Date) - MMM d HH:mm:ss
• Host (String)
• Process (String)
• PID (Number)
• Message (String)

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⚙️ Technical Details

Performance Optimizations

• UI Virtualization: Only visible rows are rendered
• Background Threading: File parsing doesn't block the UI
• Filter Optimization: Filters execute in order of computational cost
• Shared File Access: Monitor logs while they're being written

Data Types

Type	Description	Examples
String	Plain text	"ERROR", "user123"
Number	Numeric values	42, 3.14, -10
Date	Timestamps	2025-10-08 14:30:00
Enum	Categorical	DEBUG, INFO, WARN, ERROR
Boolean	True/false	true, false

Filter Operators

Operator	Cost	Description
Equals	Low	Exact match
NotEquals	Low	Exclude exact match
GreaterThan/LessThan	Low	Numeric/date comparison
Contains	Medium	Substring search
NotContains	Medium	Exclude substring
Regex	High	Pattern matching

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🐛 Troubleshooting

Problem: "No Template" error when opening files

Solution: Load or create a template first via Template → New Template or Template → Load Template

Problem: Regex doesn't match log lines

Solution:

• Test your regex at regex101.com
• Ensure capture groups match the number of columns
• Check for escaped special characters

Problem: Dates not parsing correctly

Solution: Specify the exact date format in the column definition (e.g., yyyy-MM-dd HH:mm:ss,fff)

Problem: Colors not appearing

Solution:

• Verify color hex codes (e.g., #FFCCCC)
• Check that column names in color rules match exactly
• Ensure operator matches your data (case-sensitive)

Problem: Application freezes

Solution: The app uses background threading, but very large files may take time to parse initially. Check the progress bar.

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📝 Template XML Format

<?xml version="1.0" encoding="utf-8"?>
<LogTemplate>
  <Name>My Template</Name>
  <RegexPattern>^(\d{4}-\d{2}-\d{2})\s+(\w+)\s+(.+)$</RegexPattern>
  <Columns>
    <ColumnDefinition>
      <HeaderName>Date</HeaderName>
      <DataType>Date</DataType>
      <DateFormat>yyyy-MM-dd</DateFormat>
    </ColumnDefinition>
    <ColumnDefinition>
      <HeaderName>Level</HeaderName>
      <DataType>Enum</DataType>
    </ColumnDefinition>
    <ColumnDefinition>
      <HeaderName>Message</HeaderName>
      <DataType>String</DataType>
    </ColumnDefinition>
  </Columns>
  <ColorRules>
    <ColorRule>
      <ColumnName>Level</ColumnName>
      <Operator>=</Operator>
      <Value>ERROR</Value>
      <ColorHex>#FFCCCC</ColorHex>
    </ColorRule>
  </ColorRules>
</LogTemplate>

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🤝 Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

1. Fork the repository
2. Create your feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

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📄 License

This project is licensed under the GNU GPLv3 License - see the LICENSE file for details.

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🙏 Acknowledgments

• Built with WPF (Windows Presentation Foundation)
• Inspired by the need for better log analysis tools
• Thanks to all contributors and users

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📧 Contact

For questions, suggestions, or issues, please open an issue on GitHub.

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Made with ❤️ for developers who love clean logs