I put together an ubuntu 12.04 server a couple of weeks ago and everything seemed fine until this morning.

Suddenly, I'm having trouble installing new packages - at first I thought there was something wrong with tinyproxy and so I tried installing squid instead. However, I get similar results:

Starting tinyproxy: tinyproxy: Could not open config file "/etc/tinyproxy.conf".\
...
/var/lib/dpkg/info/squid3.postinst: 1: /var/lib/dpkg/info/squid3.postinst: cannot open /etc/squid3/squid.conf: No such file

It seems that apt-get is not creating the configuration files needed for these programs.

I haven't modified any configuration or user groups since the last successful update/install of packages.

/etc is present, and is populated with a nice healthy tree of configuration files. It is owned and grouped to root, and has the properties drwxr-xr-x - all the files and folders inside seem to be fine to, as far as I can tell. I've even been able to edit/save a couple as sudo.

Full output from installing tinyproxy:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following NEW packages will be installed:
 tinyproxy
0 upgraded, 1 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/61.6 kB of archives.
After this operation, 201 kB of additional disk space will be used.
Selecting previously unselected package tinyproxy.
(Reading database ... 58916 files and directories currently installed.)
Unpacking tinyproxy (from .../tinyproxy_1.8.3-1_amd64.deb) ...
Processing triggers for ureadahead ...
Processing triggers for man-db ...
Setting up tinyproxy (1.8.3-1) ...
Starting tinyproxy: tinyproxy: Could not open config file "/etc/tinyproxy.conf".
invoke-rc.d: initscript tinyproxy, action "start" failed.
dpkg: error processing tinyproxy (--configure):
 subprocess installed post-installation script returned error exit status 70
Errors were encountered while processing:
 tinyproxy
E: Sub-process /usr/bin/dpkg returned an error code (1)

Result of strace after installation:

18467 open("/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
18467 open("/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
18467 read(3, "\177ELF\2\1\1\0\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\200\30\2\0\0\0\0\0"..., 832) = 832
18467 open("/etc/tinyproxy.conf", O_RDONLY) = -1 ENOENT (No such file or directory)