Creating a Live CD: Difference between revisions
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This page guides you through the steps required to create a Live CD of your | This page guides you through the steps required to create a Live CD of your | ||
system. The ability to create a Live CD is one of the core | system. The ability to create a Live CD is one of the core features of | ||
LFScript. | LFScript. | ||
'''All commands presented here should be executed from the LFScript directory''' | |||
== Compile your system == | == Compile your system == | ||
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== Create a system image == | == Create a system image == | ||
<pre>dd if=/dev/zero of=sources/rootfs-$(uname -m).img bs=1G | <pre>dd if=/dev/zero of=sources/rootfs-$(uname -m).img bs=1G seek=10 count=0</pre> | ||
This command should instantly create a 10GB sparse file. The file will not | This command should instantly create a 10GB sparse file. The file will not | ||
| Line 21: | Line 24: | ||
needed (up to 10GB). This means that the actual size of the file will never be | needed (up to 10GB). This means that the actual size of the file will never be | ||
greater than the minimum size needed to contain your system. | greater than the minimum size needed to contain your system. | ||
'''''Some filesystems do not support sparse files. On those systems, the above command will create a true 10GB file. For example, if you are using Ubuntu and you have your home folder encrypted (ecryptfs), you can not have sparse files anywhere in your home tree.''''' | |||
The file will be created in the <code>sources</code> directory, because the | The file will be created in the <code>sources</code> directory, because the | ||
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== Create temporary installation directories == | == Create temporary installation directories == | ||
<pre>mkdir -v | <pre>mkdir -v install_root</pre> | ||
And if you would like to keep the overhead of <code>sources</code> and | And if you would like to keep the overhead of <code>sources</code> and | ||
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size, not the ISO size): | size, not the ISO size): | ||
<pre>mkdir -v | <pre>mkdir -v install_overhead</pre> | ||
== Mount the system image == | == Mount the system image == | ||
If you installed an <code>ext4</code> fle system on the system image: | If you installed an <code>ext4</code> fle system on the system image: | ||
<pre>mount -o loop sources/rootfs-$(uname -m).img | <pre>mount -o loop sources/rootfs-$(uname -m).img install_root</pre> | ||
Or if you used <code>btrfs</code>: | Or if you used <code>btrfs</code>: | ||
<pre>mount -o loop,compress sources/rootfs-$(uname -m).img | <pre>mount -o loop,compress sources/rootfs-$(uname -m).img install_root</pre> | ||
== Install your system to the image == | == Install your system to the image == | ||
< | This installation command takes the form of <code>./lfscript [your_system_options] -i install_root -I install_overhead</code>. If you did not create the overhead directory, leave out <code>-I install_overhead</code>. | ||
For example: | |||
<pre>./lfscript -Bux fsos -i install_root -I install_overhead</pre> | |||
== Security == | |||
It is a bad idea to keep SSH keys on your Live CD, so remove them: | |||
<pre>rm -rvf install_root/etc/ssh/ssh_host_*_key</pre> | |||
< | If you have installed OpenSSH (and the OpenSSH bootscript), these keys need to be regenerated using a custom boot script. If you are not installing <code>fsos</code>, take a look at the page '[[FsOS_without_X11]]' for an example of the boot script. | ||
== Unmount the system image == | == Unmount the system image == | ||
<pre>umount | <pre>umount install_root</pre> | ||
== Build the ISO image == | == Build the ISO image == | ||
| Line 87: | Line 95: | ||
The script that builds the ISO image could just as well be designed for use | The script that builds the ISO image could just as well be designed for use | ||
outside of LFScript (and in fact, with LFScript 3 it was). However, by | outside of LFScript (and in fact, with LFScript 3 it was). However, by | ||
executing | executing [[BuildISO]] through LFScript the ISO is created by your own | ||
system, which removes the need to have the utilities required to run | system, which removes the need to have the utilities required to run | ||
[[BuildISO]] (like <code>SquashFS</code> and <code>cdrtools</code> for | |||
example) installed on your host system. This reduces the risk of build failures | example) installed on your host system. This reduces the risk of build failures | ||
considerably. | considerably. | ||
| Line 100: | Line 108: | ||
original system image which you probably don't need anymore: | original system image which you probably don't need anymore: | ||
<pre>rm -rv | <pre>rm -rvf install_root install_overhead sources/rootfs-$(uname -m).img</pre> | ||
Latest revision as of 20:22, 15 April 2017
This page guides you through the steps required to create a Live CD of your system. The ability to create a Live CD is one of the core features of LFScript.
All commands presented here should be executed from the LFScript directory
Compile your system
Although it is not required, it is highly recommended that you compile your system into packages beforehand. For example:
./lfscript -Bux fsos
This command builds all packages (except those that are only for the 32-bit version) of fsOS.
Create a system image
dd if=/dev/zero of=sources/rootfs-$(uname -m).img bs=1G seek=10 count=0
This command should instantly create a 10GB sparse file. The file will not actually take up 10GB of your precious free disk space. It's actual size will initially be zero. Once it has a file system, has been mounted and starts to contain actual files it will automatically grow and use real disk space as needed (up to 10GB). This means that the actual size of the file will never be greater than the minimum size needed to contain your system.
Some filesystems do not support sparse files. On those systems, the above command will create a true 10GB file. For example, if you are using Ubuntu and you have your home folder encrypted (ecryptfs), you can not have sparse files anywhere in your home tree.
The file will be created in the sources directory, because the
buildiso script will need to be able to find the image.
The $(uname -m) part will automatically resolve to your host
system CPU architecture (i686, x86_64, or something
else), giving the image a name like rootfs-i686.img. Using
$(uname -m) in these commands makes them suitable for copy-pasting
on any machine.
Create a file system on the image
This command should work on any machine with a recent kernel:
mkfs.ext4 -F sources/rootfs-$(uname -m).img
However, if you want to optimize for size at this stage (this does NOT affect
the size of the final ISO image) and have btrfs available you
could issue this one in stead:
mkfs.btrfs sources/rootfs-$(uname -m).img
A compressed btrfs system image will take up about 500MB of space
if you just install a basic LFS system on it, compared to 1.3GB for an
uncompressed ext4 image.
Any file system for Linux should work just fine, and it does not even matter if
the OS you will install in it has support for the file system you have
selected. Later on, the image will be converted to SquashFS
anyway.
Create temporary installation directories
mkdir -v install_root
And if you would like to keep the overhead of sources and
tools directories out of the image (only affects the system image
size, not the ISO size):
mkdir -v install_overhead
Mount the system image
If you installed an ext4 fle system on the system image:
mount -o loop sources/rootfs-$(uname -m).img install_root
Or if you used btrfs:
mount -o loop,compress sources/rootfs-$(uname -m).img install_root
Install your system to the image
This installation command takes the form of ./lfscript [your_system_options] -i install_root -I install_overhead. If you did not create the overhead directory, leave out -I install_overhead.
For example:
./lfscript -Bux fsos -i install_root -I install_overhead
Security
It is a bad idea to keep SSH keys on your Live CD, so remove them:
rm -rvf install_root/etc/ssh/ssh_host_*_key
If you have installed OpenSSH (and the OpenSSH bootscript), these keys need to be regenerated using a custom boot script. If you are not installing fsos, take a look at the page 'FsOS_without_X11' for an example of the boot script.
Unmount the system image
umount install_root
Build the ISO image
./lfscript -Bux buildiso
The script that builds the ISO image could just as well be designed for use
outside of LFScript (and in fact, with LFScript 3 it was). However, by
executing BuildISO through LFScript the ISO is created by your own
system, which removes the need to have the utilities required to run
BuildISO (like SquashFS and cdrtools for
example) installed on your host system. This reduces the risk of build failures
considerably.
Once completed, your Live CD ISO image will be saved to your
packages directory.
Cleanup
This command removes both the temporary installation directories, and the original system image which you probably don't need anymore:
rm -rvf install_root install_overhead sources/rootfs-$(uname -m).img
