Once the partition is created, we have to create a new file system on that partition. The standard file system used these days is the ext2 file system, but the so-called journaling file systems are becoming increasingly popular too. We'll assume that you wish to create an ext2 file system. However, build instructions for other file systems may be found at http://beyond.linuxfromscratch.org/view/cvs/postlfs/filesystems.html.
To create an ext2 file system, use the mke2fs command. The LFS partition is used as the only option to the command and the file system is created.
mke2fs /dev/xxx |
Replace "xxx" by the partition's designation (like hda11).