chroot is the tool for the job. Backup your data before you accidentally nuke your drive.
Shrink the partition and write a new one in the empty space, but backup your data before you accidentally nuke your drive.
Connect an external drive, install on it, but backup your data before you accidentally nuke your drive.
Finally, the reason that the wiki didn’t help is that the question is asked by either a person with not enough experience, or one who doesn’t need the wiki. This is a non trivial process and you should backup your data before you proceed, lest you accidentally nuke your drive.
Edit:
Also, anything you break can be fixed … but only if you have a backup.
Option (4) is safer in the long run because it prevents boot loaders overwriting each other.
Also, dual-booting and accessing the same data in /home IS ONLY SAFE IF YOU DO A FULL SHUTDOWN ON EACH BOOT OF THE OTHER SYSTEM. No hibernate, because hibernate does not unmount file systems.
The real question is: Why?
Here’s some answers to your question:
chrootis the tool for the job. Backup your data before you accidentally nuke your drive.Finally, the reason that the wiki didn’t help is that the question is asked by either a person with not enough experience, or one who doesn’t need the wiki. This is a non trivial process and you should backup your data before you proceed, lest you accidentally nuke your drive.
Edit:
Also, anything you break can be fixed … but only if you have a backup.
In addition to this, it’s also a good idea to backup important data first.
Option (4) is safer in the long run because it prevents boot loaders overwriting each other.
Also, dual-booting and accessing the same data in /home IS ONLY SAFE IF YOU DO A FULL SHUTDOWN ON EACH BOOT OF THE OTHER SYSTEM. No hibernate, because hibernate does not unmount file systems.
If you want to keep both running, a VM (for example running in GNOME Boxes) is both safer and much more convenient.