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VAR=value cmd is not cmd.exe syntax — npm scripts break on Windows

ci agents · case

bothhard-errorciscriptfirst-partyrepro: verifiedposix-inline-env
Affectsnode, cmd, windows
Fails asCOMMAND NOT RECOGNIZED
Mechanismposix inline env
Safe fixnode env wrapper

Symptom

Section titled “Symptom”

A package.json script like "test": "NODE_ENV=test node run.js" works for every contributor — until the first Windows contributor runs it: ‘NODE_ENV’ is not recognized as an internal or external command.

Repro

Section titled “Repro”
# cmd.exe (npm's default script shell on Windows):
NODE_ENV=test node run.js
# 'NODE_ENV' is not recognized as an internal or external command

Cause

Section titled “Cause”

VAR=value cmd is POSIX per-command environment syntax. cmd.exe has no such form — it tries to execute the literal token NODE_ENV=test as a program. npm runs scripts through cmd.exe on Windows, so the POSIX prefix silently platform-locks the script.

Workaround

Section titled “Workaround”
  • Route env-setting through a tiny Node wrapper (the referenced run-with-env.mjs pattern) or cross-env.
  • Or set variables inside the Node process; keep package.json scripts shell-neutral.

Refs

Section titled “Refs”