await-shell

await-shell

A simple utility for using child_process.spawn inside of a Promise wrapper.

Allows for the await shell(...) pattern, initially developed to play nice with the ora package, i.e.:

const ora = require('ora');
const shell = require('await-shell');

async function test() {
  const spinner = ora('Starting...').start();

  try {
    await shell('do-task arg1 arg2');
  } catch (e) {
    return spinner.fail('Something went wrong!');
  }

  spinner.succeed('All done!');
}

Examples

Will call bash (non-blocking) and run the spinner for 1 second, then exit:

const spinner = ora('Waiting...').start();
await shell('sleep 1');
spinner.succeed('All done!');

Running sequential commands:

const spinner = ora('Waiting...').start();
await shell(
  'echo "Hello"',
  'echo "World"'
);
spinner.succeed('All done!');

Output:

"Hello"
"World"
✔ All done!

Source

The package simply wraps the child_process.spawn call in a Promise which is resolved on exit and rejected on error. Multiple commands may be passed in, and they will be executed in sequential order.

index.js

const shell = async (...cmds) => {
  for (let cmd of cmds) {
    cmd = cmd.split(' ');
    await new Promise((resolve, reject) => {
      spawn(cmd.shift(), cmd, global.SHELL_OPTIONS || DEFAULTS)
      .on(
        'exit',
        (code) => {
          if (code === 0) resolve();
          else {
            if (global.SHELL_STRICT) {
              process.exit(1);
            } else {
              reject(new Error('Exited with code: ' + code));
            }
          }
        }
      );
    });
  }
}

Footnotes and global options

The options { stdio: 'inherit', shell: true } are passed to spawn by default, and stdout will be visible. For the sake of simplicity, the only arguments shell takes are commands, but you can override this setting with global.SHELL_OPTIONS if necessary.

Use global.SHELL_LOG = true to enable the printing of each command as it is executed.

Flag	Description
global.SHELL_LOG	Set to true to print commands to stdout.
global.SHELL_OPTIONS	Override arguments to child_process.spawn. Defaults to { stdio: 'inherit', shell: true }.
global.SHELL_STRICT	Instead of rejecting the Promise, call process.exit(1).