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child_process: support promisified `exec(File)`

Author: Benjamin Gruenbaum <inglor@gmail.com>
Author: Anna Henningsen <anna@addaleax.net>

PR-URL: #12442
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: William Kapke <william.kapke@gmail.com>
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
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addaleax committed Apr 16, 2017
1 parent fbcb4f5 commit fe5ca3ff27d3d94386edab0f9328df534da599aa
Showing with 74 additions and 1 deletion.
  1. +31 −0 doc/api/child_process.md
  2. +9 −1 lib/child_process.js
  3. +34 −0 test/parallel/test-child-process-promisified.js
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@@ -214,6 +214,23 @@ child runs longer than `timeout` milliseconds.
*Note: Unlike the exec(3) POSIX system call, `child_process.exec()` does not
replace the existing process and uses a shell to execute the command.*
If this method is invoked as its [`util.promisify()`][]ed version, it returns
a Promise for an object with `stdout` and `stderr` properties.
For example:
```js
const util = require('util');
const exec = util.promisify(require('child_process').exec);
async function lsExample() {
const {stdout, stderr} = await exec('ls');
console.log('stdout:', stdout);
console.log('stderr:', stderr);
}
lsExample();
```
### child_process.execFile(file[, args][, options][, callback])
<!-- YAML
added: v0.1.91
@@ -263,6 +280,19 @@ can be used to specify the character encoding used to decode the stdout and
stderr output. If `encoding` is `'buffer'`, or an unrecognized character
encoding, `Buffer` objects will be passed to the callback instead.
If this method is invoked as its [`util.promisify()`][]ed version, it returns
a Promise for an object with `stdout` and `stderr` properties.
```js
const util = require('util');
const execFile = util.promisify(require('child_process').execFile);
async function getVersion() {
const {stdout} = await execFile('node', ['--version']);
console.log(stdout);
}
getVersion();
```
### child_process.fork(modulePath[, args][, options])
<!-- YAML
added: v0.5.0
@@ -1269,4 +1299,5 @@ to `stdout` although there are only 4 characters.
[`process.on('message')`]: process.html#process_event_message
[`process.send()`]: process.html#process_process_send_message_sendhandle_options_callback
[`stdio`]: #child_process_options_stdio
[`util.promisify()`]: util.html#util_util_promisify_original
[synchronous counterparts]: #child_process_synchronous_process_creation
View
@@ -22,7 +22,9 @@
'use strict';
const util = require('util');
const { deprecate, convertToValidSignal } = require('internal/util');
const {
deprecate, convertToValidSignal, customPromisifyArgs
} = require('internal/util');
const debug = util.debuglog('child_process');
const uv = process.binding('uv');
@@ -138,6 +140,9 @@ exports.exec = function(command /*, options, callback*/) {
opts.callback);
};
Object.defineProperty(exports.exec, customPromisifyArgs,
{ value: ['stdout', 'stderr'], enumerable: false });
exports.execFile = function(file /*, args, options, callback*/) {
var args = [];
@@ -333,6 +338,9 @@ exports.execFile = function(file /*, args, options, callback*/) {
return child;
};
Object.defineProperty(exports.execFile, customPromisifyArgs,
{ value: ['stdout', 'stderr'], enumerable: false });
const _deprecatedCustomFds = deprecate(
function deprecateCustomFds(options) {
options.stdio = options.customFds.map(function mapCustomFds(fd) {
@@ -0,0 +1,34 @@
'use strict';
const common = require('../common');
const assert = require('assert');
const child_process = require('child_process');
const { promisify } = require('util');
common.crashOnUnhandledRejection();
const exec = promisify(child_process.exec);
const execFile = promisify(child_process.execFile);
{
exec(`${process.execPath} -p 42`).then(common.mustCall((obj) => {
assert.deepStrictEqual(obj, { stdout: '42\n', stderr: '' });
}));
}
{
execFile(process.execPath, ['-p', '42']).then(common.mustCall((obj) => {
assert.deepStrictEqual(obj, { stdout: '42\n', stderr: '' });
}));
}
{
exec('doesntexist').catch(common.mustCall((err) => {
assert(err.message.includes('doesntexist'));
}));
}
{
execFile('doesntexist', ['-p', '42']).catch(common.mustCall((err) => {
assert(err.message.includes('doesntexist'));
}));
}

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