Hi,

not all flavours of shutdown(8) support a time argument; for example, runit's only supports 'now' or no time.

When unattended-upgrades tries to schedule a reboot on runit systems, shutdown(8) prints an error, causing unattended-upgrades to become sad.

I'd like to provide my own mechanism for scheduling reboots (e.g. via at(1)). Please add a config tunable for this.

Thanks!

András