POSTIN

/bin/sh

if [ ! -f /etc/shells ]; then
        echo "/usr/bin/ksh" > /etc/shells
else
        if ! grep -q '^/usr/bin/ksh$' /etc/shells ; then
                echo "/usr/bin/ksh" >> /etc/shells
        fi
fi

/bin/systemctl try-restart systemd-binfmt.service >/dev/null 2>&1 || :

POSTUN

/bin/sh

if [ ! -f /bin/ksh ]; then
        sed -i '/^\/usr\/bin\/ksh$/ d' /etc/shells
fi