Command reference

Usage

lampo [file.tex | directory] [options]

Without arguments, Lampo previews the current working directory. If the directory contains main.tex, that’s the default. Otherwise, if exactly one .tex file exists, it’s selected. For multiple files, Lampo can select the unique file containing \documentclass; if ambiguous, pass a specific filename.

Option	Default	Behavior
-p, --port NUMBER	Free port	Set a fixed HTTP port (0 means random)
--host ADDRESS	127.0.0.1	Bind to another network address
--engine NAME	pdflatex	Choose pdflatex, xelatex, or lualatex
--no-open	Off	Print the URL but don’t open a browser
--open	On	Open the browser when starting
-h, --help		Show help and usage examples
-v, --version		Display the current binary version

Options can be placed before or after the project path.

Examples

lampo
lampo /path/to/resume/main.tex
lampo ./research --port 4444
lampo paper.tex --engine lualatex --no-open

Watching and compilation

• Saves to .tex, .bib, .sty, .cls, figures and other source asset types trigger builds; new nested directories are watched automatically.
• Short, burst-coalescing delays prevent duplicate rebuilds during editor saves. Superseded builds are canceled.
• Only fully compiled PDFs appear in the browser. If a build fails, the previous PDF remains readable and the error log is available.
• Window resizing and zoom respond immediately by transforming existing layers. After interaction settles, PDF.js renders fresh, crisp text at the final scale and display’s pixel density, replacing one completed page at a time without blanking or moving the preview. Intermediate resize frames never trigger expensive redraws.
• Auxiliary build files live outside the source directory and are removed when the server stops.

The browser uses bundled Mozilla PDF.js; communication is over local HTTP and server-sent events. Lampo does not require Node.js at runtime and makes no requests to a cloud service.

Security

The default listener accepts local connections (127.0.0.1). --host 0.0.0.0 exposes the preview and PDF to anyone who can reach that port, so only use it on trusted networks. Lampo does not sandbox LaTeX itself; compile trusted sources.