I have unattended-upgrade set up on my Ubuntu systems. Occasionally I will log in remotely to one of them and I'll see a message informing me that I need to reboot the system (in order to complete an upgrade). Is there a way to determine the specific package (or set of packages) which is triggering this notice?

4 Answers 4


Short version:

cat /var/run/reboot-required.pkgs


Looks like there is an easy way to automatically extract the requested information.

Inside .deb files there are control files for installation, including postinst (run after installation).

For example, in linux-image-2.6.35-25-generic_2.6.35-25.44_amd64.deb,
postinst includes

my $notifier          = "/usr/share/update-notifier/notify-reboot-required";

my $warn_reboot     = 'Yes';     # Warn that we are installing a version of
                                 # the kernel we are running


# Warn of a reboot
if (-x $notifier) {

The shell script /usr/share/update-notifier/notify-reboot-required updates
/var/run/reboot-required and /var/run/reboot-required.pkgs.

The latter file contains a list of packages requesting a reboot.

  • 2
    On my system the file /var/run/reboot-required was created a day before but there is no /var/run/reboot-required.pkgs file @ Ubuntu 16.04.5 LTS.
    – Lion
    Aug 9, 2018 at 10:51

Reboot is recommended by the unattended-upgrades when it sees that a /var/run/reboot-required exists. The file is created by postinst (post-installation) scripts in some packages, it looks something like this:

[ -x /usr/share/update-notifier/notify-reboot-required ] && \
/usr/share/update-notifier/notify-reboot-required || true

If you want to see which packages triggered this, you can have a look at the contents of the /var/run/reboot-required.pkgs file.

For more info also see this thread.


Based on Olli's earlier answer, I came up with a method to find all currently installed packages on your system that requires a reboot.

~$ mkdir debs
~$ cd debs
~/debs$ apt-get download $(dpkg -l | tail -n +7 | awk '{print $2}')

Wait for the download to complete, on my system it was around 900 MB so it might take a while depending on your connection. Then:

~/debs$ for x in $(ls); do y=$(dpkg-deb -I "$x" postinst 2>/dev/null | grep 'reboot-required'); if [ -n "$y" ]; then echo "$x" | grep -Poe '^.*?(?=_)'; fi; done

The output may look something like this:


Of course, this method is not foolproof. There might be packages that notifies about the required reboot through other means than 'notify-reboot-required', and while this shows which currently installed packages require or doesn't require a reboot, it is not certain the same will hold true for later versions of the same package.

  • 5
    You could acomplish the same without any tedious downloading with just grep -l reboot-required /var/lib/dpkg/info/*.postinst | sed -e 's,^.*/\(.*\)\.postinst,\1,'. Note however that it will only report which packages might require reboot at some time, not which package did require reboot this time Sep 1, 2017 at 15:40

I don't really know if there are other packages that require rebooting, but kernel updates always do. I'd say almost every time I've been "asked" to reboot, the kernel had been updated.

  • 1
    That's not good enough in my opinion. Bootloader updates also request rebooting, as well as init (upstart).
    – Olli
    Mar 1, 2011 at 8:59
  • 1
    Well, also some other packages, like DBus: ubuntu.com/usn/USN-799-1 . So compiling list of packages that require restart (DBus do not always require that) is foolish for complete solution.
    – Olli
    Mar 1, 2011 at 9:01
  • 1
    You're right... Mine is a partial knowledge :(. Thanks for the information. I hadn't realized other packages require restart, too.
    – luri
    Mar 1, 2011 at 11:19

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