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 /etc/passwd and /etc/group files.
Create the /etc/passwd file by running
the following command:
cat > /etc/passwd << "EOF"
root:x:0:0:root:/root:/bin/bash
EOF
The actual password for root (the
“x” used here is just a
placeholder) will be set later.
Additional users you may want to add:
bin:x:1:1:bin:/bin:/bin/false
Can be useful for compatibility with legacy applications.
daemon:x:2:6:daemon:/sbin:/bin/false
It is often recommended to use an unprivileged User ID/Group ID for daemons to run as, in order to limit their access to the system.
adm:x:3:16:adm:/var/adm:/bin/false
Was used for programs that performed administrative tasks.
lp:x:10:9:lp:/var/spool/lp:/bin/false
Used by programs for printing
mail:x:30:30:mail:/var/mail:/bin/false
Often used by email programs
news:x:31:31:news:/var/spool/news:/bin/false
Often used for network news servers
operator:x:50:0:operator:/root:/bin/bash
Often used to allow system operators to access the system
postmaster:x:51:30:postmaster:/var/spool/mail:/bin/false
Generally used as an account that receives all the information of troubles with the mail server
nobody:x:65534:65534:nobody:/:/bin/false
Used by NFS
Create the /etc/group file by running
the following command:
cat > /etc/group << "EOF"
root:x:0:
bin:x:1:
sys:x:2:
kmem:x:3:
tty:x:4:
tape:x:5:
daemon:x:6:
floppy:x:7:
disk:x:8:
lp:x:9:
dialout:x:10:
audio:x:11:
video:x:12:
utmp:x:13:
usb:x:14:
cdrom:x:15:
EOF
Additional groups you may want to add
adm:x:16:root,adm,daemon
All users in this group are allowed to do administrative tasks
console:x:17:
This group has direct access to the console
cdrw:x:18:
This group is allowed to use the CDRW drive
mail:x:30:mail
Used by MTAs (Mail Transport Agents)
news:x:31:news
Used by Network News Servers
users:x:1000:
The default GID used by shadow for new users
nogroup:x:65533:
This is a default group used by some programs that do not require a group
nobody:x:65534:
This is used by NFS
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.
To remove the “I have no
name!” prompt, start a new shell. Since a full Glibc was
installed in Constructing
Cross-Compile Tools and the /etc/passwd and /etc/group files have been created, user name and
group name resolution will now work.
exec /tools/bin/bash --login +h
Note the use of the +h
directive. This tells bash not to use its internal path
hashing. Without this directive, bash would remember the paths to
binaries it has executed. To ensure the use of the newly compiled
binaries as soon as they are installed, the +h directive will be used for the
duration of the next chapters.
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 /var/run/utmp /var/log/{btmp,lastlog,wtmp}
chgrp -v utmp /var/run/utmp /var/log/lastlog
chmod -v 664 /var/run/utmp /var/log/lastlog
chmod -v 600 /var/log/btmp
The /var/run/utmp file records the
users that are currently logged in. The /var/log/wtmp file records all logins and logouts.
The /var/log/lastlog file records when
each user last logged in. The /var/log/btmp file records the bad login attempts.