zx + pg

Usage no npm install needed!

<script type="module">
  import pgfx from '';



google/zx with builtin support for postgres.js

Quick Start

# Run a migration script with full access to zx and sql globals
npx pgfx "$DATABASE_URL"
const [{ a, b }] = await sql`select 1 as a, 2 as b`

const files = await 

	npm:pgfx | Skypack
		ls -la`

console.log('Migration OK'))




Pass a postgres connection string (just like psql), you can instead specify host/user etc as flags, or omit it entirely and use the defaults


Not all ZX functionality is supported.  We can add things on request.  But for now we're just
importing the zx library and importing and executing the provided script ourselves.

--quiet                     Run zx commands quietly
--shell                     Override the shell used by $
--prefix                    Prefix shell commands with an other command


--begin                     Run entire script within a single transaction

Connection Options:

Note: We also support standard environment variables like PGUSER, PGHOST, PGPASSWORD

-h, --host=HOST             Specify hostname (defaut
-p, --port=PORT             Specify port (default 5432)
-U, --username=USERNAME     Specify username (default 'postgres')
-X, --no-connect            Do not establish a connection automatically

    | --ssl                 Enables ssl
    | --ssl-prefer          Prefers ssl
    | --ssl-require         Requires ssl
    | --ssl-reject          Reject unauthorized connections
    | --no-ssl-reject       Do not reject unauthorized connections
    | --ssl-heroku          --no-ssl-reject if the connection string has a .com in it
    For more detailed connection options, connect to postgres manually
    via -X

Note the following is lifted almost verbatim from google/zx's documentation with a few edits to adapt for usage with postgres, please checkout out google/zx repo for the latest documentation.

CLI Options


A brief explanatation of the many SSL flags and options. The short of it is, we would all really like to enforce ssl but many hosting providers do not support SSL connections out of the box. So if you are on heroku for example, you may want to use the special --ssl-heroku which sets ssl to rejectUnauthorized: false if the PGHOST is a .com. When the host is an ip address, a local hostname, or localhost ssl will be disabled.

At such a time when Heroku supports SSL, this flag will change behaviour to --ssl, so its a good default for heroku users.

For more information on SSL connection configuration in postgres checkout the postgres.js SSL documentation.

Script Usage


Checkout postgres.js' excellent documentation for a full walkthrough of what is possible with the sql and pg global

const [user] = await sql`select * from users where user_id = ${1}`

npm:pgfx | Skypack command`

Executes a given string using the spawn function from the child_process package and returns ProcessPromise<ProcessOutput>.

let count = parseInt(await 

	npm:pgfx | Skypack
		ls -1 | wc -l`)
console.log(`Files count: ${count}`)

For example, to upload files in parallel:

let hosts = [...]
await Promise.all( =>

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		rsync -azP ./src ${host}:/var/www`

If the executed program returns a non-zero exit code, ProcessOutput will be thrown.

try {

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		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:


	npm:pgfx | Skypack
		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.


	npm:pgfx | Skypack
		pwd` // outputs /tmp


A wrapper around the node-fetch package.

let resp = await fetch('')
if (resp.ok) {
  console.log(await resp.text())


A wrapper around the readline package.


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


await nothrow(

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		grep something from-file`)

// Inside a pipe():


	npm:pgfx | Skypack
		find ./examples -type f -print0`

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		xargs -0 grep something`))

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		wc -l`)

If only the exitCode is needed, you can use the next code instead:

if (await 

	npm:pgfx | Skypack
		[[ -d path ]]`.exitCode == 0) {

// Equivalent of:

if ((await nothrow(

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		[[ -d path ]]`)).exitCode == 0) {


Packages are available without importing inside scripts.

postgres package

The postgres package.

// Available globally as both pg and postgres
const sql = postgres(connectionOptions)

chalk package

The chalk package.

console.log('Hello world!'))

fs package

The fs-extra package.

let content = await fs.readFile('./package.json')

os package

The os package.


	npm:pgfx | Skypack
		cd ${os.homedir()} && mkdir example`

minimist package

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 pgzx prints all executed commands alongside with their outputs.

Or use a CLI argument --quiet to set $.verbose = false.


__filename & __dirname

In ESM modules, Node.js does not provide __filename and __dirname globals. As such globals are really handy in scripts, pgzx provides these for use in .mjs files (when using the pgzx executable).


In ESM modules, the require() function is not defined. The pgzx provides require() function, so it can be used with imports in .mjs files (when using pgzx executable).

let {version} = require('./package.json')


Passing env variables

process.env.FOO = 'bar'

	npm:pgfx | Skypack
		echo $FOO`

Passing array of values

If array of values passed as argument to $, items of the array will be escaped individually and concatenated via space.


let files = [...]

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		tar cz ${files}`

Importing from other scripts

It is possible to make use of $ and other functions via explicit imports:

#!/usr/bin/env node
import {$} from 'pgzx'

	npm:pgfx | Skypack

Unsupported ZX features

These features were ommited without prejudice. They simply weren't available as exports on the zx library and things are a lot simpler if script execution is managed by pgzx not zx. Will happily accept PRs to add these features back.

  • Scripts without extensions
  • Markdown scripts
  • TypeScript support
  • Stdin scripts


All non referenced documentation and new code uses the MIT Licence

All referenced code and documentation from google/zx and postgres.js use their original licences:


Infinite thanks to the authors of google/zx and porsager/postgres, this package is merely a thin abstraction on top of 2 incredible API surfaces.

I never thought anyone would pry me away from bash or psql scripts but zx and postgres together create a very compelling scripting environment for migrations and operations.

Without these two packages this package would never exist.