I'm talking about resizing my root partition (/), while the system is on (I know that's usually impossible, but I'm just hoping there is some way to do it). I want to know if there is some way I can boot the system up in read-only mode (without a live cd, just in case), and resize /.
If it can't work, I understand, as that is what I already know to be the case (but you never know =P)
Best Answer
Some filesystems support "on-line" resizing, and in that case I would consider it reasonably safe unless the manpage/program warns it is not.
Most filesystems that support "on-line resize" only support making it larger (e.g. XFS, ext2/3/4, reiserfs).
Btrfs supports on-line growing and shrinking, but of course it's not as stable as a long-existing filesystem like XFS or ext4 yet.