# Emitting an Executable

> Building without a build.zig.

For a single file you do not need a build script at all:

```bash
zig build-exe main.zig          # an executable
zig build-lib  main.zig         # a static library
zig build-obj  main.zig         # an object file
zig run        main.zig         # build and run in one step
zig test       main.zig         # build and run its tests
```

## Useful flags

| Flag | Effect |
| --- | --- |
| `-O<Mode>` | optimisation mode |
| `-target <triple>` | cross-compile |
| `--name <n>` | output name |
| `-femit-bin=<path>` | where to write the binary |
| `-fstrip` | drop debug info |
| `-fsingle-threaded` | assume no threads |

## Targeting WebAssembly

This is how every snippet on this site is built:

```bash
zig build-exe main.zig -target wasm32-wasi -OReleaseSmall
```

For a freestanding wasm module with no WASI (the browser-canvas case), you
want `-target wasm32-freestanding` plus `-fno-entry` and explicit exports:

```bash
zig build-exe main.zig -target wasm32-freestanding \
  -OReleaseSmall -fno-entry --export=add
```

## When to graduate to `build.zig`

Once you have more than one artifact, dependencies, generated files, or a test
step worth naming, move to a build script. `zig build --help` then lists the
steps and options that script defines.