Final preparations

I've created the simple file system on my target partition with that script:

#!/bin/bash
export LFS=/mnt/lfs

mkdir -pv $LFS/{etc,var} $LFS/usr/{bin,lib,sbin}
for i in bin lib sbin; do
  ln -sv usr/$i $LFS/$i
done
case $(uname -m) in
  x86_64) mkdir -pv $LFS/lib64 ;;
esac

mkdir -pv $LFS/tools

[!tip] mkdir -v

I didn't know mkdir can be verbose. The same goes with mv (as I'll learn pretty soon).

Then I've added the lfs user to my Manjaro installation to reduce risk of destroying my host:

$ sudo groupadd lfs # create `lfs` group
$ sudo useradd -s /bin/bash -g lfs -m -k /dev/null lfs # create `lfs` user
$ sudo passwd lfs # set password for `lfs`

$ chown -v lfs $LFS/{usr{,/*},lib,lib64,var,etc,bin,sbin,tools} # set `/mnt/lfs` ownership to `lfs`

su - lfs # login as `lfs` (`-` stands for `login shell`, check `bash(1) manpage`)

I've cleaned up the environmental variables for lfs user with this .bash_profile and .bashrc configs:

# .bash_profile
exec env -i HOME=$HOME TERM=$TERM PS1='\u:\w\$ ' /bin/bash`

# .bashrc
set +h # make bash to always lookup $PATH when a program is about to run (disable bash's hash function)
umask 022  # ensure that created files are only writable by their owner, but are readable and executable by anyone
LFS=/mnt/lfs
LC_ALL=POSIX
LFS_TGT=$(uname -m)-lfs-linux-gnu
PATH=/usr/bin
if [ ! -L /bin ]; then PATH=/bin:$PATH; fi
PATH=$LFS/tools/bin:$PATH CONFIG_SITE=$LFS/usr/share/config.site
export LFS LC_ALL LFS_TGT PATH CONFIG_SITE

[!tip] Emptying the environment

When logging in the initial shell is usually a login shell which reads the /etc/profile of the host (probably containing some settings and environment variables) and then .bash_profile. The exec env -i [...] /bin/bash command replaces the running shell with a new one with a completely empty environment, except for what was set with that command.

The new instance of the shell is a non-login shell, which does not read, and execute, the contents of /etc/profile/.bash_profile, but rather reads, and executes, the .bashrc.

I've also renamed /etc/bashrc to /etc/bashrc.NOUSE to avoid preconfiguring bash with stuff that may interfere with the lfs (user) environment.

[!tip] /etc/bash.bashrc

Some distros add a non-documented instantiation of /etc/bash.bashrc to the initialization of bash. Manjaro does that for sure.