quota-tools
To really activate quotas, you’ll need to add usrquota to the appropriate partitions as listed in /etc/fstab. Here’s an example:
/dev/hda2 /home ext2 defaults,usrquota 1 1
When you want quota support for a given partition, some special files have to be created boot-time. This is not done by default. To do so, you need to
# touch /var/lib/quota/new
then, reboot to create those files.
To edit user quotas, use edquota. See man edquota.