In order for user root to be able to login and for the name “root” to be recognized, there must be relevant entries in the ${LFS}/etc/passwd and ${LFS}/etc/group files.

Create the ${LFS}/etc/passwd file by running the following command:

cat > ${LFS}/etc/passwd << "EOF"
root::0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/bin/false
daemon:x:2:2:daemon:/sbin:/bin/false
adm:x:3:4:adm:/var/adm:/bin/false
lp:x:10:18:lp:/var/spool/lp:/bin/false
mail:x:30:30:mail:/var/spool/mail:/bin/false
news:x:31:31:news:/var/spool/news:/bin/false
uucp:x:32:32:uucp:/var/spool/uucp:/bin/false
operator:x:50:0:operator:/root:/bin/bash
postmaster:x:51:30:postmaster:/var/spool/mail:/bin/false
nobody:x:65534:65534:nobody:/:/bin/false
EOF

The actual password for root (the “x” used here is just a placeholder) will be set later.

Create the ${LFS}/etc/group file by running the following command:

cat > ${LFS}/etc/group << "EOF"
root::0:root
bin::1:root,bin,daemon
daemon::2:root,bin,daemon
sys::3:root,bin,adm
adm::4:root,adm,daemon
kmem::5:
utmp::6:
tty::10:
video::11:root
console::12:
disk::13:root,adm
floppy::14:root
cdrom::15:
cdrw::16:
tape::17:root
lp::18:lp
usb::19:
audio::20:
dialout::21:root
mail::30:mail
news::31:news
uucp::32:uucp
users::100:
nogroup::65533:
nobody::65534:
EOF

The created groups are not part of any standard—they are groups decided on in part by the requirements of the Udev configuration in the final system, and in part by common convention employed by a number of existing Linux distributions. The Linux Standard Base (LSB, available at http://www.linuxbase.org) recommends only that, besides the group “root” with a Group ID (GID) of 0, a group “bin” with a GID of 1 be present. All other group names and GIDs can be chosen freely by the system administrator since well-written programs do not depend on GID numbers, but rather use the group's name.

The login, agetty, and init programs (and others) use a number of log files to record information such as who was logged into the system and when. However, these programs will not write to the log files if they do not already exist. Initialize the log files and give them proper permissions:

touch ${LFS}/var/run/utmp ${LFS}/var/log/{btmp,lastlog,wtmp}
chmod -v 664 ${LFS}/var/run/utmp ${LFS}/var/log/lastlog
chmod -v 600 ${LFS}/var/log/btmp

The ${LFS}/var/run/utmp file records the users that are currently logged in. The ${LFS}/var/log/wtmp file records all logins and logouts. The ${LFS}/var/log/lastlog file records when each user last logged in. The ${LFS}/var/log/btmp file records the bad login attempts.