Add the following to your /etc/apt/apt.conf:
DPkg::Pre-Invoke{“mount -o remount,exec /tmp”;};
DPkg::Post-Invoke {“mount -o remount /tmp”;};

(This remounts /tmp exec before running dpkg, then re-remounts it noexec when it’s done.)

/usr/bin/mesg n

to root’s .bashrc that I was getting mysterious errors from non-interactive processes.

Namely, when I ran rsync via cron, I was getting emails from cron that looked like this:

stdin: is not a tty
stdin: is not a tty
stdin: is not a tty

It didn’t take long for me to put two and two together and realize that this was output from that mesg command: it couldn’t do its thing because it didn’t have a tty on account of the session being a non-interactive one.

In order to silence that particular lamb, I adjusted the mesg command in root’s .bashrc:

if [ ! -f $USER ]
    then /usr/bin/mesg n
fi

It’s sort of ugly, but it gets the job done: if you’re starting an interactive session and you’ve got a $USER variable, then you get your mesg sent to n. If you’re not, then you don’t. Easy-peasy.