The Debian/Ubuntu decision to forbid non-POSIX shell features was not likely made for scripts that "rely" on strict POSIX conformance, as most shells implement

The Debian/Ubuntu decision to forbid non-POSIX shell features was not likely made for scripts that "rely" on strict POSIX conformance, as most shells implement it (bash has a POSIXLY_CORRECT mode). I think that portability and speed were greater concerns. There were many support tickets asking for bash to be restored as /bin/sh. https://bugs.launchpad.net/ubuntu/+source/dash/+bug/141481 https://bugs.launchpad.net/ubuntu/+source/dash/+bug/141481