Package: bridge-utils Version: 1.5-13+deb9u1 Followup-For: Bug #873086 I've just ran into this same bug.
I believe the proble comes from line 63 of /lib/bridge-utils/bridge-utils.sh 63 dev="${port%.*}" because this runs in a function within the containing script, it alters the value of $dev. This bug can be fixed by simply adding the 'local' keyword; thus making the line local dev="${port%.*}" to localise the value to within that one function, stopping it breaking the containing code. I can send a patch if required. -- System Information: Debian Release: buster/sid APT prefers testing APT policy: (990, 'testing'), (500, 'unstable') Architecture: amd64 (x86_64) Kernel: Linux 4.15.0-2-amd64 (SMP w/4 CPU cores) Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8), LANGUAGE=en_GB:en (charmap=UTF-8) Shell: /bin/sh linked to /bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages bridge-utils depends on: ii libc6 2.27-2 bridge-utils recommends no packages. Versions of packages bridge-utils suggests: ii ifupdown 0.8.31