Core modules: path, os, and process

Reference for three Node core modules: node:path (string path manipulation), node:os (live host reporting), and node:process (the running process, also the global process). Lists exactly which functions, properties, and lifecycle events are implemented and which are not.

This page is the reference for three focused-tier core modules. All three are substantially implemented and safe to rely on for the surfaces listed here: node:path is pure string manipulation (POSIX-canonical, with a partial win32 namespace); node:os reports the live host; node:process (also the global process) reports and controls the running process, including the lifecycle events. Anything not listed in the tables below is not present.

Import forms

const path = require("node:path");      // or "path"
import path from "node:path";
const os = require("node:os");          // or "os"
import os from "node:os";
const process = require("node:process"); // rarely needed: `process` is a global

node:path

String-only path manipulation; no filesystem is touched. The top-level module is the POSIX implementation.

Example:

$ cruft -e 'const p = require("node:path");
console.log(p.join("a", "b", "..", "c"));
console.log(p.resolve("/foo", "bar"));
console.log(p.relative("/a/b", "/a/c"));
console.log(p.dirname("/a/b/c.txt"));
console.log(p.basename("/a/b/c.txt"));
console.log(p.extname("/a/b/c.txt"));'
a/c
/foo/bar
../c
/a/b
c.txt
.txt

path.win32 caveat

path.win32 exists and exposes the Windows sep (\), and win32.join now emits backslash-separated paths. It is still backed by POSIX logic underneath, so do not rely on full drive-letter / UNC normalization semantics:

$ cruft -e 'const p = require("node:path");
console.log(p.win32.sep);
console.log(p.win32.join("C:\\a", "b"));'
\
C:\a\b

Treat path.win32 as POSIX logic exposing a Windows sep. It is not a faithful Windows path engine.

node:os

Host reporting. Note the Node convention: os.platform()/os.arch() are functions, while process.platform/process.arch are string properties.

Example:

$ cruft -e 'const os = require("node:os");
console.log(os.platform());
console.log(os.arch());
console.log(os.tmpdir());
console.log(os.homedir());'
linux
x64
/tmp
/home/jaredef

node:process (and the global process)

process is a global, no import needed.

Identity and environment

$ cruft -e 'console.log(process.platform);
console.log(process.arch);
console.log(process.version);
console.log(process.cwd());'
linux
x64
v20.10.0
/home/jaredef/Developer/cruftless-r8

argv, running a script file:

$ cat /tmp/argvtest.mjs
console.log(process.argv.slice(2).join(","));

$ cruft /tmp/argvtest.mjs alpha beta
alpha,beta

Methods

process.exit example:

$ cruft -e 'process.exit(3); console.log("after");'; echo "exit: $?"
exit: 3

stdout / stderr

process.stdout and process.stderr are minimal writable shapes: .write(str) (capability-gated per stream), .isTTY (false), .fd, .columns, .rows, and a no-op .on. They are enough for the module-load isTTY color probes real libraries do; they are not full streams. process.stdin is a real Readable EventEmitter.

Lifecycle events

process is a real EventEmitter for non-signal events. These listener methods are all functional:

Not implemented / gaps

• path.win32 is POSIX-backed (see caveat); no drive-letter or UNC semantics.
• process.memoryUsage() reports real rss, heapTotal, and heapUsed; external and arrayBuffers are still 0.
• process.stdout/stderr are minimal shapes, not full Writable streams (no cork, pipe, backpressure, or 'drain').
• 'uncaughtException' handlers fire for both synchronous and async throws, but do not resume the event loop afterward the way Node's do.
• Signal listeners cannot be removed (process.off on a signal is not wired).
• Anything not listed above (e.g. process.send, process.channel, os.setPriority beyond the basic form, worker-related process surface) is not present.