適性アップデートのためのUbuntu 12.04ボックスをどのように入手しますか？

その後、Ubuntu 12.04システムで実行して次のようにaptitude apt-getなりました。aptitude upgrade

root@li393-189:~# aptitude upgrade
Resolving dependencies...                
The following packages will be upgraded:
  accountsservice apache2 apache2-mpm-prefork apache2-utils apache2.2-bin 
  apache2.2-common apparmor apport apt-transport-https apt-utils bind9-host 
  dmsetup dnsutils icedtea-6-jre-cacao icedtea-6-jre-jamvm initramfs-tools 
  initramfs-tools-bin iptables isc-dhcp-client isc-dhcp-common 
  postfix-doc python-apport python-problem-report rsyslog sudo
  ubuntu-minimal udev upstart
The following partially installed packages will be configured:
  apt
The following packages are RECOMMENDED but will NOT be installed:
  firefox-locale-en libssl-doc
76 packages upgraded, 0 newly installed, 0 to remove and 9 not upgraded.
Need to get 4,168 kB/60.3 MB of archives. After unpacking 1,225 kB will be used.
Do you want to continue? [Y/n/?] Y
Get: 1 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libdevmapper1.02.1 i386 2:1.02.48-4ubuntu7.3 [67.4 kB]
Get: 2 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main dmsetup i386 2:1.02.48-4ubuntu7.3 [36.9 kB]
Get: 3 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libxml2 i386 2.7.8.dfsg-5.1ubuntu4.4 [662 kB]
Get: 4 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main rsyslog i386 5.8.6-1ubuntu8.1 [431 kB]
Get: 5 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main bind9-host i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [54.0 kB]
Get: 6 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main dnsutils i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [143 kB]
Get: 7 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libisc83 i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [161 kB]
Get: 8 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libdns81 i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [705 kB]
Get: 9 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libisccc80 i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [18.0 kB]
Get: 10 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libisccfg82 i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [40.3 kB]
Get: 11 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main liblwres80 i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [38.8 kB]
Get: 12 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libbind9-80 i386 1:9.8.1.dfsg.P1-4ubuntu0.6 [24.4 kB]
Get: 13 http://us.archive.ubuntu.com/ubuntu/ precise-updates/main libruby1.8 i386 1.8.7.352-2ubuntu1.2 [1,787 kB]
Fetched 4,168 kB in 0s (11.4 MB/s) 
Extracting templates from packages: 100%
Preconfiguring packages ...
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_create_maildirsize=yes
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_maildir_extended=yes
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_create_maildirsize=yes
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_maildir_extended=yes
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_create_maildirsize=yes
postconf: warning: /etc/postfix/main.cf: unused parameter: virtual_maildir_extended=yes
Setting up apt (0.8.16~exp12ubuntu10.10) ...
gpg: error while loading shared librariesgpg: error while loading shared libraries: libgdbm.so.2: cannot open shared object file: No such file or directory
: libgdbm.so.2: cannot open shared object file: No such file or directory
dpkg: error processing apt (--configure):
 subprocess installed post-installation script returned error exit status 127
No apport report written because MaxReports is reached already
                                                              Errors were encountered while processing:
 apt
E: Sub-process /usr/bin/dpkg returned an error code (1)
A package failed to install.  Trying to recover:
Setting up apt (0.8.16~exp12ubuntu10.10) ...
gpg: error while loading shared libraries: libgdbm.so.2: cannot open shared object file: No such file or directory
gpg: error while loading shared libraries: libgdbm.so.2: cannot open shared object file: No such file or directory
dpkg: error processing apt (--configure):
 subprocess installed post-installation script returned error exit status 127
Errors were encountered while processing:
 apt 

このエラーを解決し、最新のUbuntu 12.04バージョンにアップグレードしてから、distroを最新の12.10バージョンにアップグレードするにはどうすればよいですか？