My Linux Practice

Setting the $LFS variable and mounting the partition

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by

Heidi
in

For some reason I found it difficult and confusing to write out the procedure for this before starting. (Yes, I make a written procedure for every session.) Google AI Mode got involved.

Exploring

First I checked out a variety of things to be used in the next sections.

I looked at startup files in ~ and /etc with ls -A, and then less.

I expected these files to not exist because they were not on my other Ubuntu machine, and they didn’t:
~/bash_profile
~/bash_login

These files exist:
Login shell session
~/.profile
/etc/profile
Non-login shell session
~/.bashrc
/etc/bash.bashrc

Here’s what’s in ~ :
Directories: .cache, .config, .fontconfig, .gnupg, .local, .pki, .ssh
Files: .bash_history, .bash_logout, .bashrc, .lesshst, .profile, .sudo_as_admin_successful

I copied the existing startup files (bash.bashrc, .bashrc, .profile, profile) into a new directory in my home called File_Backups. I know that’s not how to do it, but I just wanted a copy somewhere else that would have the exact text of the files.

Then I found the UUID of the LFS partition:

sudo blkid

Environment

For 2.6 Setting the $LFS variable and the umask.

  1. Set LFS variable
export LFS=mnt/lfs

2. Set file mode creation mask

umask 022

Do I need to add a 0 in Ubuntu? No, umask ignores the prefix digit.
This removes the group and world w. Directory default: 755, Files default: 644

3. Verify them

echo $LFS
umask

4. Now add the following lines:

# Set LFS variable and file mode creation mask for Linux From Scratch

export LFS=/mnt/lfs
umask 022

Into these startup files with nano:

sudo nano /etc/profile
nano ~/.profile
sudo nano /etc/bash.bashrc
nano ~/.bashrc

In /etc/bash.bashrc, must go before “if” test

5. Restart. To see if everything’s ok.

Mounting LFS (temporary)

  1. Create directory for LFS (apparently on the mount point). [parent, verbose]
mkdir -pv $LFS

2. Make sure I know the device name of the LFS partition. It should be sda3, but it could change on reboot, etc.

lsblk

3. Mount the LFS partition

sudo mount -v -t ext4 /dev/sda3 $LFS

4. Check if it is mounted at the right location

mount
    /dev/sda3 on /mnt/lfs type ext4 (rw,relatime)

5. Set owner and permission mode of $LFS directory, i.e. the root directory in the newly created file system for the system.

chown root:root $LFS
chmod 755 $LFS

Notes: Everyone can read, only owner can write. Group and world have permission to enter directly and list contents.
chown newowner:newgroup file
chmod mode directory
755: rwx r-x r-x or 111 101 101

6. Be sure it is not mounted with permissions that are too restrictive. If nosuid or nodev are set, the partition must be remounted.

Find this with

mount

Defaults: Use the default mount options (usually rw, suid, dev, exec, auto, nouser, async)