Wild

Wild is an attempt at giving tools and tips to run any Linux system entirely in RAM (tmpfs).

Wild stands for "What if...? Linux Distribution". It's arguably a Linux distribution, yet this is arguable, as here is delivered my own flavour of a complete and usable Linux system.

But i won't argue, the aim being arguably to come by a fancy acronym, recalling it all began with this lil' but utterly-time-consuming question.

What does it do ?

Basically, a full-fledged, yet elementary, Debian system is launched from a removeable medium, and charged in RAM (hence the removeable medium can be removed). The system should have network capabilities set or easily set with minor tweaks. This system prepares the ground for another Linux system to be aptly chroot'ed', copies (or deflates through cpio or tar archive) the chrooted-to-be system in RAM, and chroots it.

As far as i know, it could be any system, only architecture limitations apply. Of, cource, the more refined, or complicated, or demanding, the targeted system (or desktop) is, the more tweaks and adaptations it could require.

I did what i could to ease this part, if you have suggestions, and/or better ideas, they are much welcome.

Use

You'll need to be able to generate and burn an .iso image (genisoimage). Also have a Linux system that could fit into your machine's RAM. Then :

git clone https://github.com/lacravate/wild.git`
wild/scripts/generate_wild.sh wild/

You'll have wild.iso ready in the current directory. Boot (see Tips below) on this ISO 9660 image, and if you have a system installed on sda1 (first disk drive), you should be able to check if all this was worth the time you took.

If your machine is on a network with DHCP service, eth0 link should be up and elementary Debian should be accessible (aside from the console of course) through ssh on port 2222.

Tweaks

Configuration

The existence of a provision/provision.cfg file will be checked and sourced as as shell script to export variables.

export ROOT_DEVICE=/dev/sda5 # partition were chrooted-to-be system is if it is not on
                      # /dev/sda1
export HOSTNAME=host # if host name wild is not good for you
export HOME_DEVICE=/dev/sdf1 # the partition holding the /home directory, if any
export ROOT_PASSWORD=root #wanna set the root password of the elementary Debian ?
export BOOTUP=/home/startup.sh # when system is chrooted, launches this script to
                               # setup a few things on chrooted system

Files

Any file found under the provision/live directory on installation/configuration medium will be copied to "main" (elementary Debian) system.

For instance, a provision/live/etc/network/interfaces will be copied to /etc/network/interfaces on the in-RAM main system. This could allow you to setup a network interface suiting your needs (if DHCP is no good for you).

Note on media

In search for this provision directory, media will be search starting from floppy drive, to USB drives, and eventually CD-DVD drives. Hence, this directory does not need to be on the installation medium, preventing you from generating and burning the iso image again and again.

This can come particularly handy for virtual machines that could not be launched from USB sticks : boot would be achieved from an unchanged iso image, while configuration could be changed easily altered on a virtual floppy.

Tips

Singular for the time being.

Boot from USB stick

Linux makes it a childish game once you know it. You need to have the isohybrid command available (found it in the syslinux package in Debian and Ubuntu).

isohybrid wild.iso
dd if=wild.iso of=/dev/sdc # for a USB stick mapped on this device

I suppose you need to be root, at least for the dd.

And then, you can fill the provision subdirectory with anything you need.

How and why so ?

The removeable medium boots with isolinux (because it's easy to use and dead-simple to re-configure), the Init RAM Disk (initrd) is the classic vestigial Linux system, with two differences. The first is that the archive embarks the target elementary Debian system, the second being that there is no pivot_root that's made to a "on disk" system. The Debian system is inflated in RAM, and is given control afterwards.

"The main goal being the operation of another system, possibly a whole desktop thingy, why not copying directly this system in RAM ?"

I prefer to have an almost immortal, "failutmostsafe" system (as the elementary Debian should be), that will boot, and that i know i can rely on. Also, the initrd system has really limited capabilites. So it's really a hassle to setup once and for all, with that system, the procedure to chroot on any target system.

Credits

debirf project gave me a some inspiration, as well lots of elementary material.

All the Linux people landing such an astonishingly versatile system, with which limits to what you can do are those of your own daring or imagination.

Copyright

I was tempted by the WTFPL, but i have to take time to read it. So far see LICENSE.