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manual: add Deno.run example (#1811)

This commit is contained in:
Bartek Iwańczuk 2019-02-21 21:52:35 +01:00 committed by Ryan Dahl
parent 8c6d6b2832
commit 9d025facaa
2 changed files with 53 additions and 39 deletions

View file

@ -8,7 +8,7 @@ import { ReadCloser, WriteCloser } from "./io";
import { readAll } from "./buffer";
import { assert, unreachable } from "./util";
/** How to handle subsubprocess stdio.
/** How to handle subprocess stdio.
*
* "inherit" The default if unspecified. The child inherits from the
* corresponding parent descriptor.
@ -101,6 +101,18 @@ function stdioMap(s: ProcessStdio): msg.ProcessStdio {
}
}
/**
* Spawns new subprocess.
*
* Subprocess uses same working directory as parent process unless `opt.cwd`
* is specified.
*
* Environmental variables for subprocess can be specified using `opt.env`
* mapping.
*
* By default subprocess inherits stdio of parent process. To change that
* `opt.stdout`, `opt.stderr` and `opt.stdin` can be specified independently.
*/
export function run(opt: RunOptions): Process {
const builder = flatbuffers.createBuilder();
const argsOffset = msg.Run.createArgsVector(

View file

@ -312,68 +312,70 @@ file_server --reload
### Run subprocess
```
const p = Deno.run({
args: ["deno", "--allow-read", "https://deno.land/x/examples/cat.ts", "README.md"],
});
[API Reference](https://deno.land/typedoc/index.html#run)
// start subprocess
await p.status();
Example:
```ts
async function main() {
// create subprocess
const p = Deno.run({
args: ["echo", "hello"]
});
// await its completion
await p.status();
}
main();
```
When this program is started, the user is prompted for permission to run
subprocess:
Run it:
```
> deno https://deno.land/x/examples/subprocess_simple.ts
⚠️ Deno requests access to run a subprocess. Grant? [yN] y
```
For security reasons, deno does not allow programs to run subprocess without
explicit permission. To avoid the console prompt, use a command-line flag:
```
> deno https://deno.land/x/examples/subprocess_simple.ts --allow-run
> deno --allow-run ./subprocess_simple.ts
hello
```
By default when you use `deno.run()` subprocess inherits `stdin`, `stdout` and
`stdout` of parent process. If you want to communicate with started subprocess
you can use `"piped"` option.
```
const decoder = new TextDecoder();
```ts
async function main() {
const decoder = new TextDecoder();
const filesToCat = Deno.args.slice(1);
const subprocessArgs = ["deno", "--allow-read", "https://deno.land/x/examples/cat.ts", ...filesToCat];
const fileNames = Deno.args.slice(1);
const p = Deno.run({
subprocessArgs,
const p = Deno.run({
args: [
"deno",
"--allow-read",
"https://deno.land/x/examples/cat.ts",
...fileNames
],
stdout: "piped",
stderr: "piped",
});
stderr: "piped"
});
const { code } = await p.status();
const { code } = await p.status();
if (code === 0) {
const rawOutput = await Deno.readAll(p.stdout);
const output = decoder.decode(rawOutput);
console.log(output);
} else {
const rawErr = await Deno.readAll(p.stderr);
const err = decoder.decode(rawErr);
console.log(err);
const rawOutput = await p.output();
Deno.stdout.write(rawOutput);
Deno.exit(code);
}
Deno.exit(code);
main();
```
When you run it:
```
> deno https://deno.land/x/examples/subprocess.ts --allow-run <somefile>
> deno ./subprocess.ts --allow-run <somefile>
[file content]
> deno https://deno.land/x/examples/subprocess.ts --allow-run non_existent_file.md
> deno ./subprocess.ts --allow-run non_existent_file.md
Uncaught NotFound: No such file or directory (os error 2)
at DenoError (deno/js/errors.ts:19:5)