Package: ifupdown-extra Version: 0.25 On systems with dash as the default shell, the 00check-network-cable script can exit with an error.
This error can cause some network configuration in /etc/network/interfaces to be left unprocessed. On my system, the IPv6 portion of a dual stack configuration remains unapplied. Example of the script having an error: # IFACE=eth0 dash 00check-network-cable 00check-network-cable: 72: local: detected:: bad variable name However, running the following produces no errors. # IFACE=eth0 bash 00check-network-cable The system boots correctly with full network configuration applied if the system’s default shell is changed to bash, or if the #!/bin/sh line is changed to #!/bin/bash Debian policy discourages undeclared bashisms - if this package requires bash, it should have the appropriate dependencies and specify #!/bin/bash as its shell. Alternatively, the script can be written in a dash-safe shell language subset.