`[ "$1" -eq "$1" ]` accepts more than a natural number:
a leading `+`, and leading or trailing whitespace,
and in ksh it evaluates its operands as arithmetic expressions,
so words like `install` and expressions like `1+1` or `V=1` pass too.
Values with any non-digit character are now rejected before that test.
The sunos and aix branches of `nvm_get_make_jobs` count cores with `wc -l`,
which on those platforms pads the count with whitespace,
so that count is now stripped of whitespace before it is checked
Discovered by Anthropic's OSS Scanner, as bug ANT-2026-SYLQD6PZ; the scanner correctly classified it as not a vulnerability.
Jordan Harband
813b5f6dcc