Alpine uses busybox for its shell and core utils. While closer to pure POSIX than bash or GNU, it has support for a few non-POSIX features (the shell supports t

Alpine uses busybox for its shell and core utils. While closer to pure POSIX than bash or GNU, it has support for a few non-POSIX features (the shell supports the source command and brace expansion, and iirc some of the utils support non-standard flags). It would be better to ensure POSIX shell script compliance by running the scripts with dash shell instead.