Linux From Scratch - Version arm64-r12.2-119-systemd

Chapter 7. Entering Chroot and Building Additional Temporary Tools

7.13. Cleaning up and Saving the Temporary System

7.13.1. Cleaning

First, remove the currently installed documentation files to prevent them from ending up in the final system, and to save about 35 MB: 

rm -rf /usr/share/{info,man,doc}/*

Second, on a modern Linux system, the libtool .la files are only useful for libltdl. No libraries in LFS are loaded by libltdl, and it's known that some .la files can cause BLFS package failures. Remove those files now: 

find /usr/{lib,libexec} -name \*.la -delete

The current system size is now about 3 GB, however the /tools directory is no longer needed. It uses about 1 GB of disk space. Delete it now: 

rm -rf /tools

7.13.2. Backup

At this point the essential programs and libraries have been created and your current LFS system is in a good state. Your system can now be backed up for later reuse. In case of fatal failures in the subsequent chapters, it often turns out that removing everything and starting over (more carefully) is the best way to recover. Unfortunately, all the temporary files will be removed, too. To avoid spending extra time to redo something which has been done successfully, creating a backup of the current LFS system may prove useful.

[Note]

Note

All the remaining steps in this section are optional. Nevertheless, as soon as you begin installing packages in Chapter 8, the temporary files will be overwritten. So it may be a good idea to do a backup of the current system as described below.

The following steps are performed from outside the chroot environment. That means you have to leave the chroot environment first before continuing. The reason for that is to get access to file system locations outside of the chroot environment to store/read the backup archive, which ought not be placed within the $LFS hierarchy.

If you have decided to make a backup, leave the chroot environment: 

exit
[Important]

Important

All of the following instructions are executed by root on your host system. Take extra care about the commands you're going to run as mistakes made here can modify your host system. Be aware that the environment variable LFS is set for user lfs by default but may not be set for root.

Whenever commands are to be executed by root, make sure you have set LFS.

This has been discussed in Section 2.6, “Setting The $LFS Variable.”

Before making a backup, unmount the virtual file systems: 

mountpoint -q $LFS/dev/shm && umount $LFS/dev/shm
umount $LFS/dev/pts
umount $LFS/{sys,proc,run,dev}

Make sure you have at least 1 GB free disk space (the source tarballs will be included in the backup archive) on the file system containing the directory where you create the backup archive.

Note that the instructions below specify the home directory of the host system's root user, which is typically found on the root file system. Replace $HOME by a directory of your choice if you do not want to have the backup stored in root's home directory.

Create the backup archive by running the following command:

[Note]

Note

Because the backup archive is compressed, it takes a relatively long time (over 10 minutes) even on a reasonably fast system. 

cd $LFS
tar -cJpf $HOME/lfs-temp-tools-arm64-r12.2-119-systemd.tar.xz .
[Note]

Note

If continuing to chapter 8, don't forget to reenter the chroot environment as explained in the “Important” box below.

7.13.3. Restore

In case some mistakes have been made and you need to start over, you can use this backup to restore the system and save some recovery time. Since the sources are located under $LFS, they are included in the backup archive as well, so they do not need to be downloaded again. After checking that $LFS is set properly, you can restore the backup by executing the following commands:

[Warning]

Warning

The following commands are extremely dangerous. If you run rm -rf ./* as the root user and you do not change to the $LFS directory or the LFS environment variable is not set for the root user, it will destroy your entire host system. YOU ARE WARNED. 

cd $LFS
rm -rf ./*
tar -xpf $HOME/lfs-temp-tools-arm64-r12.2-119-systemd.tar.xz

Again, double check that the environment has been set up properly and continue building the rest of the system.

[Important]

Important

If you left the chroot environment to create a backup or restart building using a restore, remember to check that the virtual file systems are still mounted (findmnt | grep $LFS). If they are not mounted, remount them now as described in Section 7.3, “Preparing Virtual Kernel File Systems” and re-enter the chroot environment (see Section 7.4, “Entering the Chroot Environment”) before continuing.