os has no getpid

import os
print(os.getpid())   # error: undefined variable (os)

The diagnostic is the same misleading one [[bug-n-os-has-no-rmdir]] documents: an absent MEMBER of a module that resolves fine is reported as the module being an undefined variable, so the reader looks at the import.

Why this is not a five-line fix

compiler/builtin/pypal.pas holds six NR_* blocks, one per target (grep -c 'NR_' answers 153 constants across them). rmdir needed none of them — PyPalRmdir reuses NR_UNLINKAT with PYPAL_AT_REMOVEDIR = 512, and the comment beside that constant says so in its own words: "this reuses NR_UNLINKAT rather than adding a syscall number to all six tables."

getpid has no such shortcut. It needs six correct numbers (x86-64 39, i386 20, aarch64 172, arm32 20, riscv 172, wasm32 -1/unsupported — those are from memory and must be re-derived from the kernel headers, not copied from this ticket, per the rule that an assertion written from a report pins the report).

Cross-target hazard worth knowing before starting

Six hand-written numbers is exactly the shape where x86-64 is right and a 32-bit target is silently wrong, and the dev loop only runs x86-64 — so assert a RELATION, not a constant, or add a row per target. PyPalSupported already gives the wasm32 arm somewhere honest to land.

Residual this ticket does NOT cover

shutil.rmtree is still absent (no member rmtree came of the qualifier shutil), and tempfile.TemporaryDirectory cannot be written without it. That belongs to track B / lib/rtl, not here.