clover's git

the-knife

1	---
2	title: Command
3	description: Alchemy's cloud-agnostic primitives for local processes in the deploy graph — memoized builds, one-off commands, and dev servers.
4	---
5
6	The Command provider puts local child processes into the Stack's
7	dependency graph: `Build` for a command that produces an output
8	asset, `Exec` for a command run purely for its side effects, and
9	`Dev` for a long-lived dev server. There is no setup — no
10	credentials, nothing to configure. `Command.providers()` is already
11	merged into both `AWS.providers()` and `Cloudflare.providers()`, so
12	big-hub users have it for free; a standalone Stack registers it with
13	`{ providers: Command.providers(), state: Alchemy.localState() }`.
14	Import from `alchemy/Command`.
15
16	## Resources
17
18	`Build` runs a command that must produce an output asset (`outdir`)
19	and tracks it in state:
20
21	```typescript
22	const build = yield* Command.Build("vite-build", {
23	command: "npm run build",
24	cwd: "./frontend",
25	outdir: "dist",
26	});
27	yield* Console.log(build.outdir); // path to the dist directory, relative to process.cwd()
28	yield* Console.log(build.hash.output); // hash of the output files (when memo is enabled)
29	```
30
31	Inputs are content-hashed by default, so an unchanged project skips
32	the rebuild entirely — see [Memoization](/command/memoization) for
33	how the hash is computed and how to scope it.
34
35	`Exec` runs a command purely for its side effects:
36
37	```typescript
38	yield* Command.Exec("codegen", {
39	command: "npm run codegen",
40	cwd: "./packages/api",
41	});
42
43	yield* Command.Exec("migrate", {
44	command: "npm run db:migrate",
45	env: {
46	DATABASE_URL: Redacted.make("postgres://..."),
47	},
48	});
49	```
50
51	There is no output contract: the resource succeeds iff the command
52	exits with code `0`, is skipped when its inputs are unchanged, and
53	re-runs when the `command`, `env`, or memoized files change — e.g. a
54	recreated database's connection URL with identical files. Deleting
55	an `Exec` never reverses its side effects.
56
57	`Dev` runs a long-lived process scoped to the stack instance:
58
59	```typescript
60	const dev = yield* Command.Dev("Frontend", {
61	command: "npm run dev",
62	});
63	yield* Console.log(dev.url); // e.g. "http://localhost:5173"
64	```
65
66	`Dev` only runs during `alchemy dev` — during `alchemy deploy` it is
67	a no-op. See [Dev servers](/command/dev-servers) for the process
68	lifecycle, restarts, and URL extraction.
69
70	:::caution
71	Command strings are whitespace-split into a binary and arguments —
72	there is no quoting support unless you set `shell`. `Build`'s delete
73	removes the output directory (`Exec`'s delete does nothing).
74	`Redacted` env values are unwrapped at spawn time and kept out of
75	logs and state.
76	:::
77
78	Pre-beta.58 `Build.Command` / `Build.DevServer` state converges
79	automatically to `Command.Build` / `Command.Dev` on the next deploy
80	([beta.58](/blog/2026-06-24-beta-58)).
81
82	## Compose with your cloud
83
84	The static-site guides for
85	[Cloudflare](/cloudflare/frontend/static-site) and
86	[AWS](/aws/frontend/static-site) create a `Command.Build` (and, in
87	dev mode, a `Command.Dev`) under the hood, and
88	[`alchemy dev`](/cli/dev) is the loop that hosts `Dev` processes.
89
90	## Reference
91
92	[Build](/providers/command/build) ·
93	[Dev](/providers/command/dev) ·
94	[Exec](/providers/command/exec)