Bug#991930: ifenslave: ifstate command does not exists

[debian-bug-ifenslave <debian-bug-ifenslave@protonmail.com>]

Package: ifenslave 
Version: 2.12

Problem while trying to bring up bond0 or any bonding interface.

ifup[933]: No iface stanza found for master bond0

The root cause is ifenslave shipped with a script, referring to ifstate command which is not present.

Script:/etc/network/if-pre-up.d/ifenslave 

...
setup_slave_device() {

    # Require the bond master to have an iface stanza
    if ! ifstate -l "$IF_BOND_MASTER" 2>/dev/null ; then
        echo "No iface stanza found for master $IF_BOND_MASTER" >&2
        exit 1
    fi
...

To fix switched to ip command that achieve the same goal

...
setup_slave_device() {
    # Require the bond master to have an iface stanza
    if ! ip link show dev "$IF_BOND_MASTER" 2>/dev/null; then
        echo "No iface stanza found for master $IF_BOND_MASTER" >&2
        exit 1
    fi
...

Debian 11.0 (5.10.0-8-amd64 #1 SMP Debian 5.10.46-3 (2021-07-28) x86_64 GNU/Linux)

Reference:

https://blog.rtsp.us/debian-11-bullseye-bonding-problem-9d8d8866117e