LogFish (VS Code Extension)

Open massive log files in a custom editor with streaming + regex filtering + per-line highlighting.

Usage

• Run LogFish: Open Log File from the Command Palette.
• Or use explorer context menu and Open in LogFish.
• Or open a file matching logFish.fileAssociations (defaults to *.log).

Filter

Use the filter input at the top of the view. The extension will try rg (ripgrep) first, then grep, and only fall back to the built-in JavaScript regex engine if neither command is available.

Highlight Rules

Highlight rules can come from either:

1. VS Code settings: logFish.highlightRules
2. Workspace override file: .vscode/logfish.rules.json

The .vscode/logfish.rules.json file can be either an array or an object with a rules key. Rules can be plain per-line rules or grouped by file path regex. Standalone rules are global and always apply. Grouped rules use the first matching filePattern only, so order matters.

Rule fields:

• pattern: Regex applied to each line.
• patternIgnoreCase: Optional boolean to ignore case for pattern.

Group fields:

• filePattern: Regex applied to the full file path.
• filePatternIgnoreCase: Optional boolean to ignore case for filePattern.
• rules: Array of per-line rules.

[
  {
    "pattern": "ERROR",
    "patternIgnoreCase": true,
    "color": "#fff",
    "background": "#c62828",
    "fontWeight": "bold"
  }
]

Grouped rules example:

[
  {
    "filePattern": "/var/log/nginx/.*\\.log$",
    "filePatternIgnoreCase": true,
    "rules": [
      { "pattern": "404", "color": "#ffffff", "background": "#ef6c00" }
    ]
  },
  {
    "filePattern": "/var/log/app/.*\\.log$",
    "rules": [
      { "pattern": "ERROR", "color": "#ffffff", "background": "#c62828", "fontWeight": "bold" }
    ]
  }
]

Settings

• logFish.fileAssociations: Glob patterns to associate with the LogFish custom editor.
• logFish.highlightRules: Array of per-line highlight rules or grouped rules with filePattern (first matching group wins).
• logFish.maxDisplayedLines: Limit for lines kept in the UI (default 1000000).
• logFish.filterDelayMs: Debounce time for the filter input.