The previous SIGNUM variable was required (${SIGNUM:?...}), which
broke for users with their own OS accounts who shouldn't need to set
anything manually. Replace with ${SIGNUM:-${USER}} so:
- Own-account mode: leave SIGNUM unset in .env — project name and
container name default to devbox-$USER automatically. Each OS
user gets isolated volumes with zero configuration.
- Shared-account mode: set SIGNUM=<id> in .env as before.
Both container_name and the top-level name: field use the same
fallback, so volumes and container names stay consistent.
Updated .env.shared.example to document both modes with the SIGNUM
line commented out by default (own-account is the common case).
For machines where multiple users share one OS account. Each user gets
isolated containers, config, and named volumes by running docker compose
from their own directory with a unique SIGNUM in .env.
joakimp