# TexLive Compilers

**LaTeX has several compilers**, each with different capabilities and output. The most common are `pdflatex`, `xelatex`, and `lualatex`. They all read `.tex` files and produce output (PDF by default).

**pdflatex** is the standard compiler. It's fast, stable, and widely supported. It directly produces PDF output and is best for most documents.

```bash
pdflatex document.tex
```

pdflatex uses traditional TeX fonts (Computer Modern) and font encoding (8-bit). Non-Latin characters and modern font formats require extra setup. It's the most conservative but most portable choice.

**xelatex** uses Unicode natively and supports modern system fonts (TrueType, OpenType). Better for non-Latin scripts, custom fonts, and internationalization.

```bash
xelatex document.tex
```

The `.tex` file remains the same; just compile with `xelatex` instead. You can use any font installed on your system:

```latex
\usepackage{fontspec}
\setmainfont{DejaVu Serif}
\setsansfont{DejaVu Sans}
```

xelatex is slower than pdflatex but handles modern fonts and Unicode naturally.

**lualatex** is like xelatex but uses Lua scripting for extensibility. It's newer and less widely used but powerful for complex document generation.

```bash
lualatex document.tex
```

**Comparison:**

| Feature | pdflatex | xelatex | lualatex |
|---------|----------|---------|----------|
| Speed | Fast | Slow | Slow |
| Unicode | Limited | Yes | Yes |
| System fonts | No | Yes | Yes |
| Stability | Very stable | Stable | Newer |
| Use case | General | International, custom fonts | Advanced scripting |

**When to use each:** Start with `pdflatex` for simple documents. If you need custom fonts or non-Latin scripts, switch to `xelatex`. Use `lualatex` only if you need Lua scripting.

**Output format:** All three produce PDF by default. To generate DVI (device-independent format) instead, use `pdftex -output-format=dvi document.tex` (rare nowadays). PostScript output (`dvips`) is mostly obsolete.

**Compilation chain with BibTeX:**

```bash
pdflatex main.tex      # first pass
bibtex main            # extract citations
pdflatex main.tex      # second pass
pdflatex main.tex      # third pass (resolve references)
```

The same process works for all three compilers. BibTeX works the same way regardless.

**Font caching:** xelatex and lualatex cache fonts. Clear the cache if you install new fonts: `rm -rf ~/.cache/fontconfig` (Linux), then recompile.