Se a sua distribuição for Ubuntu Lucid.
Teste isso:
Abra um terminal
Pressione Ctrl + Alt + T
Execute:
sudo -i
nano /etc/apt/sources.list
No arquivo aberto, exclua o conteúdo e cole isso:
## Uncomment the following two lines to fetch updated software from the network
deb http://old-releases.ubuntu.com/ubuntu lucid main restricted
deb-src http://old-releases.ubuntu.com/ubuntu lucid main restricted
## Uncomment the following two lines to fetch major bug fix updates produced
## after the final release of the distribution.
deb http://old-releases.ubuntu.com/ubuntu lucid-updates main restricted
deb-src http://old-releases.ubuntu.com/ubuntu lucid-updates main restricted
## Uncomment the following two lines to add software from the 'universe'
## repository.
## 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
## universe WILL NOT receive any review or updates from the Ubuntu security
## team.
deb http://old-releases.ubuntu.com/ubuntu lucid universe
deb-src http://old-releases.ubuntu.com/ubuntu lucid universe
deb http://old-releases.ubuntu.com/ubuntu lucid-security main restricted
deb-src http://old-releases.ubuntu.com/ubuntu lucid-security main restricted
deb http://old-releases.ubuntu.com/ubuntu lucid-security universe
deb-src http://old-releases.ubuntu.com/ubuntu lucid-security universe
deb http://old-releases.ubuntu.com/ubuntu lucid multiverse
deb-src http://old-releases.ubuntu.com/ubuntu lucid multiverse
deb http://old-releases.ubuntu.com/ubuntu lucid-backports main restricted universe multiverse
Ctrl + O , salve o arquivo. Ctrl + X , perto do nano.
Continue a execução em um terminal:
sudo -i
apt-get update
apt-get dist-upgrade
apt-get install flex bison
apt-get clean
Se a sua distribuição não for Ubuntu Lucid, altere o Lucid para o nome apropriado.
Se nada disso funcionar
Download de pacotes (Lucid):
link (32 bits) link (64 bits) link (32 bits) link (64 bits)
E instale-os com:
sudo -i
cd /home/user/Downloads
dpkg -i *.deb