@npmcli/promise-spawn

Spawn processes the way the npm cli likes to do. Give it some options,
it'll give you a Promise that resolves or rejects based on the results of
the execution.

USAGE

``js
const promiseSpawn = require('@npmcli/promise-spawn')

promiseSpawn('ls', [ '-laF', 'some/dir/*.js' ], {
cwd: '/tmp/some/path', // defaults to process.cwd()
stdioString: true, // stdout/stderr as strings rather than buffers
stdio: 'pipe', // any node spawn stdio arg is valid here
// any other arguments to node child_process.spawn can go here as well,
}, {
extra: 'things',
to: 'decorate',
the: 'result',
}).then(result => {
// {code === 0, signal === null, stdout, stderr, and all the extras}
console.log('ok!', result)
}).catch(er => {
// er has all the same properties as the result, set appropriately
console.error('failed!', er)
})
`

API

$3

Run the command, return a Promise that resolves/rejects based on the
process result.

Result or error will be decorated with the properties in the extra
object. You can use this to attach some helpful info about _why_ the
command is being run, if it makes sense for your use case.

If stdio is set to anything other than 'inherit', then the result/error
will be decorated with stdout and stderr values. If stdioString is
set to true, these will be strings. Otherwise they will be Buffer
objects.

Returned promise is decorated with the stdin stream if the process is set
to pipe from stdin. Writing to this stream writes to the stdin of the
spawned process.

#### Options

- stdioString Boolean, default true. Return stdout/stderr output as
strings rather than buffers.
- cwd String, default process.cwd(). Current working directory for
running the script. Also the argument to infer-owner to determine
effective uid/gid when run as root on Unix systems.
- shell Boolean or String. If false, no shell is used during spawn. If true,
the system default shell is used. If a String, that specific shell is used.
When a shell is used, the given command runs from within that shell by
concatenating the command and its escaped arguments and running the result.
This option is _not_ passed through to child_process.spawn.
- Any other options for child_process.spawn can be passed as well.

$3

Use the operating system to open arg with a default program. This is useful
for things like opening the user's default browser to a specific URL.

Depending on the platform in use this will use start (win32), open (darwin)
or xdg-open (everything else). In the case of Windows Subsystem for Linux we
use the default win32 behavior as it is much more predictable to open the arg
using the host operating system.

#### Options

Options are identical to promiseSpawn except for the following:

- command String, the command to use to open the file in question. Default is
one of start, open or xdg-open` depending on platform in use.