#!/usr/bin/env zx
await $`cat package.json | grep name`
let branch = await $`git branch --show-current`
await $`dep deploy --branch=${branch}`
await Promise.all([
$`sleep 1; echo 1`,
$`sleep 2; echo 2`,
$`sleep 3; echo 3`,
])
let name = 'foo bar'
await $`mkdir /tmp/${name}`
Bash is great, but when it comes to writing scripts,
people usually choose a more convenient programming language.
JavaScript is a perfect choice, but standard Node.js library
requires additional hassle before using. The zx
package provides
useful wrappers around child_process
, escapes arguments and
gives sensible defaults.
npm i -g zx
Node.js >= 14.8.0
Write your scripts in a file with .mjs
extension in order to
be able to use await
on top level. If you prefer the .js
extension,
wrap your scripts in something like void async function () {...}()
.
Add the following shebang to the beginning of your zx
scripts:
#!/usr/bin/env zx
Now you will be able to run your script like so:
chmod +x ./script.mjs
./script.mjs
Or via the zx
executable:
zx ./script.mjs
All functions ($
, cd
, fetch
, etc) are available straight away
without any imports.
Executes a given string using the spawn
function from the
child_process
package and returns ProcessPromise<ProcessOutput>
.
let count = parseInt(await $`ls -1 | wc -l`)
console.log(`Files count: ${count}`)
For example, to upload files in parallel:
let hosts = [...]
await Promise.all(hosts.map(host =>
$`rsync -azP ./src ${host}:/var/www`
))
If the executed program returns a non-zero exit code,
ProcessOutput
will be thrown.
try {
await $`exit 1`
} catch (p) {
console.log(`Exit code: ${p.exitCode}`)
console.log(`Error: ${p.stderr}`)
}
class ProcessPromise<T> extends Promise<T> {
readonly stdin: Writable
readonly stdout: Readable
readonly stderr: Readable
readonly exitCode: Promise<number>
pipe(dest): ProcessPromise<T>
}
The pipe()
method can be used to redirect stdout:
await $`cat file.txt`.pipe(process.stdout)
Read more about pipelines.
class ProcessOutput {
readonly stdout: string
readonly stderr: string
readonly exitCode: number
toString(): string
}
Changes the current working directory.
cd('/tmp')
await $`pwd` // outputs /tmp
A wrapper around the node-fetch package.
let resp = await fetch('http://wttr.in')
if (resp.ok) {
console.log(await resp.text())
}
A wrapper around the readline package.
Usage:
let bear = await question('What kind of bear is best? ')
let token = await question('Choose env variable: ', {
choices: Object.keys(process.env)
})
In second argument, array of choices for Tab autocompletion can be specified.
function question(query?: string, options?: QuestionOptions): Promise<string>
type QuestionOptions = { choices: string[] }
A wrapper around the setTimeout
function.
await sleep(1000)
Changes behavior of $
to not throw an exception on non-zero exit codes.
function nothrow<P>(p: P): P
Usage:
await nothrow($`grep something from-file`)
// Inside a pipe():
await $`find ./examples -type f -print0`
.pipe(nothrow($`xargs -0 grep something`))
.pipe($`wc -l`)
If only the exitCode
is needed, you can use the next code instead:
if (await $`[[ -d path ]]`.exitCode == 0) {
...
}
// Equivalent of:
if ((await nothrow($`[[ -d path ]]`)).exitCode == 0) {
...
}
Next packages is available without importing inside scripts.
The chalk package.
console.log(chalk.blue('Hello world!'))
The fs-extra package.
let content = await fs.readFile('./package.json')
The globby package.
let packages = await globby(['package.json', 'packages/*/package.json'])
let pictures = globby.globbySync('content/*.(jpg|png)')
The os package.
await $`cd ${os.homedir()} && mkdir example`
The minimist package.
Available as global const argv
.
Specifies what shell is used. Default is which bash
.
$.shell = '/usr/bin/bash'
Or use a CLI argument: --shell=/bin/bash
Specifies the command that will be prefixed to all commands run.
Default is set -euo pipefail;
.
Or use a CLI argument: --prefix='set -e;'
Specifies a function for escaping special characters during command substitution.
Specifies verbosity. Default is true
.
In verbose mode, the zx
prints all executed commands alongside with their
outputs.
Or use a CLI argument --quiet
to set $.verbose = false
.
In ESM modules, Node.js does not provide
__filename
and __dirname
globals. As such globals are really handy in scripts,
zx
provides these for use in .mjs
files (when using the zx
executable).
In ESM
modules, the require()
function is not defined.
The zx
provides require()
function, so it can be used with imports in .mjs
files (when using zx
executable).
let {version} = require('./package.json')
process.env.FOO = 'bar'
await $`echo $FOO`
If array of values passed as argument to $
, items of the array will be escaped
individually and concatenated via space.
Example:
let files = [...]
await $`tar cz ${files}`
It is possible to make use of $
and other functions via explicit imports:
#!/usr/bin/env node
import {$} from 'zx'
await $`date`
If script does not have a file extension (like .git/hooks/pre-commit
), zx
assumes that it is an ESM
module.
The zx
can execute scripts written in markdown
(examples/markdown.md):
zx examples/markdown.md
The zx
can compile .ts
scripts to .mjs
and execute them.
zx script.ts
In TypeScript file include the zx
package to import types:
import 'zx'
Or reference the zx
package via:
/// <reference types="zx"/>
Example:
#!/usr/bin/env zx
import 'zx'
void async function () {
await $`ls -la`
}()
If the argument to the zx
executable starts with https://
, the file will be
downloaded and executed.
zx https://medv.io/example-script.mjs
Disclaimer: This is not an officially supported Google product.