analyze-log-files

majiayu000's avatarfrom majiayu000

Analyze log files by stripping ANSI escape sequences first. Use when asked to process, handle, read, or analyze log files that may contain terminal escape codes.

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[Debugging]

When & Why to Use This Skill

This Claude skill optimizes log file analysis by automatically stripping ANSI escape sequences, such as terminal colors and formatting codes. By converting garbled terminal output into clean, plain text, it ensures that logs are searchable, readable, and accurately interpretable by AI, significantly accelerating the debugging and troubleshooting process.

Use Cases

  • Cleaning terminal-captured logs: Removing ANSI color codes and cursor movement sequences from logs saved directly from a console session to make them human-readable.
  • Debugging build and test failures: Processing output from build tools (e.g., Cargo, Webpack) to isolate specific error messages from complex terminal formatting.
  • System log preprocessing: Preparing application or system logs for LLM analysis to prevent escape sequence artifacts from causing parsing errors or hallucinations.
  • Search optimization: Converting raw logs into clean text to enable efficient pattern matching and filtering using standard tools like grep or ripgrep.
nameanalyze-log-files
descriptionAnalyze log files by stripping ANSI escape sequences first. Use when asked to process, handle, read, or analyze log files that may contain terminal escape codes.

Analyze Log Files

When to Use

  • When user asks to "analyze log.txt", "read the log file", "process logs", "check the logs"
  • When dealing with any .log or log-related files that may contain ANSI escape sequences
  • When terminal output has been captured to a file and needs analysis
  • When log files appear garbled or contain escape sequence artifacts

Why This Matters

Log files captured from terminal sessions often contain ANSI escape sequences for:

  • Colors (e.g., \x1b[31m for red)
  • Cursor movements
  • Text formatting (bold, underline)
  • Screen clearing commands

These sequences make logs difficult to:

  1. Read in plain text editors
  2. Search with grep/ripgrep
  3. Process with text analysis tools
  4. Analyze accurately by LLMs

Instructions

Step 1: Strip ANSI Escape Sequences

Before analyzing any log file, first strip the ANSI sequences using ansifilter:

ansifilter -i log.txt -o /tmp/clean_log.txt

For other log file names, adjust accordingly:

ansifilter -i <input_file> -o /tmp/clean_log.txt

Step 2: Analyze the Clean Log

Read and analyze /tmp/clean_log.txt instead of the original file:

# Use the Read tool on /tmp/clean_log.txt

Step 3: Report Findings

When reporting findings to the user:

  • Reference line numbers from the clean log
  • Quote relevant sections
  • Summarize errors, warnings, or patterns found

Common Log File Locations

  • log.txt - General purpose log in project root
  • target/ - Cargo build logs
  • /tmp/*.log - Temporary logs

Example Workflow

User: "Can you analyze log.txt and tell me what's wrong?"

  1. Run: ansifilter -i log.txt -o /tmp/clean_log.txt
  2. Read: /tmp/clean_log.txt
  3. Analyze the content for errors, warnings, patterns
  4. Report findings to user

Troubleshooting

If ansifilter is not installed:

# Ubuntu/Debian
sudo apt-get install ansifilter

# macOS
brew install ansifilter

# Or run bootstrap.sh to install all dependencies
./bootstrap.sh
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