LargeFileViewer (Rust, Windows x64 friendly)

A terminal-based large file viewer implemented in Rust that uses a memory-mapped file so it can inspect huge files without loading them fully into process heap memory.

Why this design

• Uses memmap2 to map the file into virtual memory.
• Builds a compact line-offset index (Vec<usize>) once.
• Renders only the currently visible lines in the terminal viewport.
• Scrolling updates just the visible window.

This pattern is ideal for large logs, CSVs, and text dumps.

Opening a 1GB Xml file in realtime

Download

Download latest release

Build

cargo build --release --target x86_64-pc-windows-msvc

If you are already on Windows x64 with Rust MSVC toolchain installed, this generates:

target/x86_64-pc-windows-msvc/release/lfv.exe

Run

cargo run -- path/to/very_large_file.log

Useful options:

• --csv: align comma-separated fields into columns.
• --xml: enable rudimentary XML syntax highlighting.
• --format: pretty-prints --xml or --json input into indented lines.
• --json: enable rudimentary JSON syntax highlighting.
• --tab-width N: set visual tab width (default: 4).

Controls

• q: quit
• ↑ / ↓: scroll one line
• PageUp / PageDown: scroll by one terminal page
• Home / End: jump to start/end

Notes

• Best with text files (UTF-8 or ASCII-like content).
• Non-printable bytes are shown as ·.
• Tabs render as spaces (default width 4, configurable with --tab-width).