It is time to create some structure in the LFS file system. Create a directory tree. Issuing the following commands will create a standard tree:

install -d /{bin,boot,dev,etc/opt,home,lib,mnt}
install -d /{sbin,srv,usr/local,var,opt}
install -d /root -m 0750
install -d /tmp /var/tmp -m 1777
install -d /media/{floppy,cdrom}
install -d /usr/{bin,include,lib,sbin,share,src}
ln -s share/{man,doc,info} /usr
install -d /usr/share/{doc,info,locale,man}
install -d /usr/share/{misc,terminfo,zoneinfo}
install -d /usr/share/man/man{1,2,3,4,5,6,7,8}
install -d /usr/local/{bin,etc,include,lib,sbin,share,src}
ln -s share/{man,doc,info} /usr/local
install -d /usr/local/share/{doc,info,locale,man}
install -d /usr/local/share/{misc,terminfo,zoneinfo}
install -d /usr/local/share/man/man{1,2,3,4,5,6,7,8}
install -d /var/{lock,log,mail,run,spool}
install -d /var/{opt,cache,lib/{misc,locate},local}
install -d /opt/{bin,doc,include,info}
install -d /opt/{lib,man/man{1,2,3,4,5,6,7,8}}

Directories are, by default, created with permission mode 755, but this is not desirable for all directories. In the commands above, two changes are made—one to the home directory of user root, and another to the directories for temporary files.

The first mode change ensures that not just anybody can enter the /root directory—the same as a normal user would do with his or her home directory. The second mode change makes sure that any user can write to the /tmp and /var/tmp directories, but cannot remove other users' files from them. The latter is prohibited by the so-called “sticky bit,” the highest bit (1) in the 1777 bit mask.