scrolex

It's like a ⌚ Rolex, except it has nothing to do with Rolexes and executes commands instead.

Scrolex executes commands, captures & scrolls back the output, optionally prefixing and overwriting each last line with the next. Here, a demo works better:

Demo

Install

yarn add scrolex || npm install scrolex --save

Use

First, require scrolex:

const scrolex = require('scrolex')

Execute a shell command:

scrolex.exe('ls -al', { }, (err, stdout) => {
  const lsOutput = stdout
})

Execute without a shell:

scrolex.exe(['/bin/sh', 'ls', '-al'], { }, (err, stdout) => {
  const lsOutput = stdout
})

Do not copy the command's output to the terminal:

scrolex.exe('ls -al', { mode: 'silent' }, (err, stdout) => {
  const lsOutput = stdout
})

Overrule environment

scrolex.exe('ls -al', { env: { YOUR_SECRET: 'not-safe-with-me' } }, (err, stdout) => {
  const lsOutput = stdout
})

Announce the command you are executing:

scrolex.exe('ls -al', { announce: true }, (err, stdout) => {
  const lsOutput = stdout
})

// Announce also leaves a sticky line: `Successfully executed: ls -al` or `Failed to execute: ls -al`

Prefix output with ✔ myapp ❯ prepare ❯:

scrolex.exe('ls -al', { components: 'myapp>prepare' }, (err, stdout) => {
  const lsOutput = stdout
})

Add some ephemeral output, respecting the currently set prefix:

scrolex.scroll('i will be overwritten by anything with the same prefix')

Add some sticky output, respecting the currently set prefix:

scrolex.stick('i will stick around, no matter what')

Use async/await for shell-scripting super-powers ⚡

const serialExecution = async () => {
  try {
    const cores = await scrolex.exe('getconf _NPROCESSORS_ONLN')
    if (cores > 10) {
      await scrolex.stick(`You have ${cores} cpu cores. Amazing!`)
    }
    const processTree = await scrolex.exe('ps auxf', { silent: true })
  } catch (err) {
    throw new Error(err)
  }  
}
serialExecution()

Use Promises for ... yeah why would you. But the important thing is you can!:

scrolex.exe('ls -al')
  .then((stdout) => {
    const lsOutput = stdout
  })
  .catch((err) => {
    throw new Error(err)
  })

Options

fatal

If set to true, whenever exe yields a non-zero exit code, the whole process stops with a dump of the combined stderr & stdout on-screen. Useful for shell-scripting tasks. Default: false.

env

Allows to specify the executed program's environment. If you want to add environment on top of the current environment use something like:

env: Object.assign({}, process.env, {
  YOUR_SECRET: 'not-safe-with-me',
}),

Default: process.env.

Global State (?!?!!!?‼️❓)

Yes, by default Scrolex uses global state (global.scrolex) within a Node process to keep track of output and so that options can be re-used across instances if you set them with persistOpts. This makes it so that consequent calls can be lightweight, as well as the output consistent looking.

If you'd rather ditch convenience in favor of strictness, or this causes a hard time testing, you are welcome to pass in your own state object, and Scrolex will happily use that instead:

const myLocalStateObject = {}
scrolex.exe('ls -al', { state: myLocalStateObject })

You can even pass a new state object each time to avoid any kind of magic inheritance:

scrolex.exe('ls -al', { state: {} })

Here's how to make all subsequent scrolex.exe() calls add their currently executing command to the prefix:

scrolex.persistOpts({
  addCommandAsComponent: true
})

You can also persist upon requiring:

const scrolex = require('./Scrolex').persistOpts({
  mode: 'silent',
})
scrolex.exe('ls -al', (err, out) => {
  
})

Todo

See CHANGELOG.md

Changelog

See CHANGELOG.md

Authors

• Kevin van Zonneveld

Related Projects

• listr: Nicer I'd say, but it does impose its structure on your code

License

Copyright (c) 2017 Kevin van Zonneveld. Licenses under MIT.