18-09-2014 | Remy van Elst
This is a response on a great article from Pascal Bourguignon, namely how to run Emacs as PID 1.
As we all know, nobody uses emacs.
The above statement is ment to start a flamewar. Please do so, see the contact page to contact me.
No, all joking aside, I found it to be a good article and wanted to see how I could do that with Vim. Not in User Mode Linux, but by creating an actual ISO. Boot to Vim, as you might want to call it.
This is actually fairly simple. Compile vim statically, set it as init=
at boot and you're done.
We are going to use small (9MB) distro named Tiny Core, Core edition and customize that to boot right into our static build of Vim.
If you like this article and want to support me AND get $10 Digital Ocean credit (2 months free), use this link to order: https://www.digitalocean.com/?refcode=7435ae6b8212
Please read and follow my tutorial on building a statically linked Vim. This will give you an executable we will use later on in the tutorial.
You will need a few tools to build the ISO, namely cpio
, tar
, gzip
, advdef
and mkisofs
. These can probably be installed with your package manager. Please do that first.
First create a folder for building:
mkdir vim-as-pid-1
cd vim-as-pid-1
Also create a few folders for the ISO build:
mkdir /tmp/isomount
mkdir extract
Download the latest Tiny Core, Core edition (without GUI):
wget http://distro.ibiblio.org/tinycorelinux/5.x/x86/release/Core-current.iso
Copy the files from the ISO:
mount Core-current.iso /tmp/isomount/ -o loop,ro
cp -a /tmp/isomount/boot /tmp/
This creates a /tmp/boot
folder with the core.gz
and boot loader. Don't forget to umount it:
umount /tmp/isomount
We will use the /tmp/boot
folder later on when putting back together the ISO.
Go into the folder where we will extract the core.gz
root filesystem:
cd extract
Use zcat
and cpio
to extract the core.gz
rootfs:
zcat /tmp/boot/core.gz | cpio -i -H newc -d
We now have an extracted root filesystem:
# ls
bin dev etc home init lib linuxrc mnt opt proc root run sbin sys tmp usr var
Place the earlier built static Vim in the bin/
folder:
cp ~/vim bin/
You can do more customizations, for example, editing the boot loader message. That is in a file named boot.msg
in /tmp/boot/isolinux/
:
# vim /tmp/boot/isolinux/boot.msg
^L
_
( - Boot to Vim
//\ Vim as Pid 1, because Awesome!
v_/_ https://raymii.org/
Press <Enter> to begin or F2, F3, or F4 to view boot options.
To boot in to Vim right away we need to change the init configuration. Edit the following file:
vim etc/inittab
Change the following lines:
::sysinit:/etc/init.d/rcS
tty1::respawn:/sbin/getty 38400 tty1
To:
::sysinit:/bin/vim
tty1::respawn:/bin/vim
Do note that this does not actually make Vim PID 1. Init will still manage Vim, and do stuff like fsck
and mount the root partition read/write. If you want to go barebones, add init=/bin/vim
to the bootloader (isolinux.cfg
). Then, from Vim, do :!fsck /dev/sda
and mount -o remount,rw /
.
Make sure you are still in the extract
folder. Issue the following command to build a new tinycore.gz
file which the ISO will use as it's initramfs
:
find | cpio -o -H newc | gzip -2 > ../tinycore.gz
Copy that over the original core.gz
file in /tmp/boot
which we copied ealier:
cp ../tinycore.gz /tmp/boot/core.gz
Create a new folder for the new ISO build files:
mkdir /tmp/newiso
Copy the /tmp/boot
folder to it:
cp -a /tmp/boot /tmp/newiso/
Build a new ISO using mkisofs
:
cd /tmp/
mkisofs -l -J -R -V Boot_To_Vim -no-emul-boot -boot-load-size 4 -boot-info-table -b boot/isolinux/isolinux.bin -c boot/isolinux/boot.cat -o Boot_to_Vim.iso newiso
You now have a file in /tmp
named Boot_to_Vim.iso
:
ls -la /tmp/Boot_to_Vim.iso
-rw-r--r-- 1 root root 11044864 Sep 17 08:05 /tmp/Boot_to_Vim.iso
You can use this to boot a VM, or burn an ISO. If you exit vim
, it will restart.
You can start up a real shell by giving the :!sh
command, in command mode. To shut down, issue the :!halt
command.
More info on remastering Tiny Core can be found here.