1

I updated a server from 14.04 to 16.04. Now apt-get update does not work anymore. I get the following errors:

0% [2 InRelease gpgv 11.5 kB] [Connecting to archive.ubuntu.com (91.189.91.26)]
dpkg: warning: failed to open configuration file '/root/.dpkg.cfg' for reading: Permission denied
/usr/bin/apt-key: 316: /usr/bin/apt-key: cannot create /dev/null: Permission denied
gpgv: Signature made Thu Apr 28 20:16:42 2016 CEST using DSA key ID 437D05B5
gpgv: Can't check signature: public key not found

I can see that some child-processes of apt-get are running as user _apt, but I don’t know how to check apt-key and dpkg.

scp from a remote host also doesn’t work anymore with a similar error message:

Couldn't open /dev/null: Permission denied

Currently ls -alh /dev/null gives

crw------- 1 root root 1, 3 Apr 26 12:51 /dev/null

How can I fix the permissions? Maybe somebody with a fresh 16.04 install can give a comparison.

2

/dev/null should have 0666 permissions and that is what /etc/udev/rules.d/device-permissions.rules says:

KERNEL=="null|zero|full|random|urandom", MODE="0666"

But unfortunately this is a virtual server. So the kernel has not been updated:

# uname -a
Linux memocamp 2.6.32-042stab063.2 #1 SMP Tue Oct 23 16:24:09 MSK 2012 x86_64 x86_64 x86_64 GNU/Linux

A temporary fix is to manually set the permissions:

chmod go+rw /dev/null

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