Re: [gentoo-user] fstab/mount riddle...how?

Meino.Cramer@×××.de wrote:

> Hi,
>
> ...still fiddling with Linux on my ASUS MeMO Pad 7... ;)
>
> Current status:
> SDCard:
> Back from extFAT (toooooo slllooooooww) to FAT32
> On this SDCard two file, each 4GB in sizse and formatted ext4
> One conatins currently the complete Linux (used as chroot environment)
> The second one contains a copy of /usr (that is, the second image
> contains /usr - not only its ontents).
>
> I finally want to get rid of the /usr on the first file to get more
> space for upgrades, intstallations and such.
>
> While using the chrooted environment (completly booted from the first
> file) I did
>
> mount /dev/sdcard /mnt
> losetup /dev/loop(x) /mnt/frstfile.img
> mount  /dev/loop(x) /image
> mount --bind /image/usr /usr
>
> This way the /usr of the first image file was somehow
> "knocked off" and the (identical) /usr of the second image
> file tooks its place.
>
> It works so far.
>
> Now the problem:
> How can I manipulate /etc/fstab (and may be others) in a
> way that /usr of the second image file permanently replaces
> /usr of the first image file AND gives me the change to remove
> /usr of the first image file?

I forgot something in my last post.

Shouldn't it possible to use fstab entries like these:

/dev/sdcard		/mnt	auto	defaults	0 0
/mnt/frstfile.img	/usr	auto	loop		0 0

If mounting with fstab doesn't work, you can place a script under 
/etc/local.d/ that will do the mount for you. But I don't know if this 
works if you are using systemd.

It's many years ago that I used loop devices and I can barely remember 
it. So maybe I'm totally wrong here. :-)

--
Regards
wabe