Não foi possível localizar o pacote pkgconfig

Eu tento instalar o Ruby no Ubuntu 12. Há um dos comandos que me dá um erro

E: Não foi possível localizar o pacote pkgconfig

sudo apt-get install build-essential openssl libreadline6 libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison subversion pkgconfig
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Note, selecting 'libxslt1-dev' instead of 'libxslt-dev'
Note, selecting 'libncurses5-dev' instead of 'ncurses-dev'
E: Unable to locate package pkgconfig

Eu até fiz

sudo apt-get update && sudo apt-get install pkgconfig

mas não ajudou.

Como instalo o pkgconfig?

Se isso ajuda você de alguma forma

alex@ubuntu:~$ cat /etc/apt/sources.list
# deb cdrom:[Kubuntu 12.10 _Quantal Quetzal_ - Release amd64 (20121017.1)]/ quantal main multiverse restricted universe

# See http://help.ubuntu.com/community/UpgradeNotes for how to upgrade to
# newer versions of the distribution.
deb http://archive.ubuntu.com/ubuntu quantal main restricted
deb-src http://archive.ubuntu.com/ubuntu quantal main restricted

## Major bug fix updates produced after the final release of the
## distribution.
deb http://archive.ubuntu.com/ubuntu quantal-updates main restricted
deb-src http://archive.ubuntu.com/ubuntu quantal-updates main restricted

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu
## team. Also, please note that software in universe WILL NOT receive any
## review or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu quantal universe
deb-src http://archive.ubuntu.com/ubuntu quantal universe
deb http://archive.ubuntu.com/ubuntu quantal-updates universe
deb-src http://archive.ubuntu.com/ubuntu quantal-updates universe

## N.B. software from this repository is ENTIRELY UNSUPPORTED by the Ubuntu 
## team, and may not be under a free licence. Please satisfy yourself as to 
## your rights to use the software. Also, please note that software in 
## multiverse WILL NOT receive any review or updates from the Ubuntu
## security team.
deb http://archive.ubuntu.com/ubuntu quantal multiverse
deb-src http://archive.ubuntu.com/ubuntu quantal multiverse
deb http://archive.ubuntu.com/ubuntu quantal-updates multiverse
deb-src http://archive.ubuntu.com/ubuntu quantal-updates multiverse

## N.B. software from this repository may not have been tested as
## extensively as that contained in the main release, although it includes
## newer versions of some applications which may provide useful features.
## Also, please note that software in backports WILL NOT receive any review
## or updates from the Ubuntu security team.
deb http://archive.ubuntu.com/ubuntu quantal-backports main restricted universe multiverse
deb-src http://archive.ubuntu.com/ubuntu quantal-backports main restricted universe multiverse

deb http://archive.ubuntu.com/ubuntu quantal-security main restricted
deb-src http://archive.ubuntu.com/ubuntu quantal-security main restricted
deb http://archive.ubuntu.com/ubuntu quantal-security universe
deb-src http://archive.ubuntu.com/ubuntu quantal-security universe
deb http://archive.ubuntu.com/ubuntu quantal-security multiverse
deb-src http://archive.ubuntu.com/ubuntu quantal-security multiverse

## Uncomment the following two lines to add software from Canonical's
## 'partner' repository.
## This software is not part of Ubuntu, but is offered by Canonical and the
## respective vendors as a service to Ubuntu users.
# deb http://archive.canonical.com/ubuntu quantal partner
# deb-src http://archive.canonical.com/ubuntu quantal partner

## Uncomment the following two lines to add software from Ubuntu's
## 'extras' repository.
## This software is not part of Ubuntu, but is offered by third-party
## developers who want to ship their latest software.
# deb http://extras.ubuntu.com/ubuntu quantal main
# deb-src http://extras.ubuntu.com/ubuntu quantal main

Eu acho que você está procurando pkg-config(com o traço), veja dpkg -l | grep pkg-config.