Request for union mount.

One of the nice things about tar is that it can be used to update an already existing folder. Currently, I mount the tar file in a separate directory, move the directory that I want the tar file to another directory, and then use unionfs-fuse to merge the just moved directory, and the mounted tar.

I wish there was an easier way to do this.

[vrthra]

Excellent! I think with the new unionmount feature. It works well. I can even use it as a superior alternative to GNU Stow! It lets me keep base configuration in a read only folder, and machine specific changes in a union mount. Thanks again for the great tool.

[mxmlnkn]

I tried the thing with cd’ing into the directory to be union mounted over. However, without the --foreground option, FUSE seems to cd into / after I cd’ed into the directory, so the union mount will always show / and ~I can’t seem to circumvent that~. I took a look at what bindfs does and it uses fdopen on the directory, then calls fuse, and then calls fchdir to change to the directory given by the opened and still valid file descriptor. I might be able to get this to work.

Here are some other now outdated options:

• Currently, ratarmount allows to union mount multiple TAR files with ratarmount tar1 tar2 mountFolder. I could extend this to ratarmount folder1 folder2 tar1 tar2 mountFolder to get a union mount of the two folders and the two TAR files into the mountFolder. By checking that the mountFolder is different from the other folders, I would ensure that I can simply access the folders to be union mounted without any cd tricks.
• I could create a hardlink to the original folder to be mounted over. I’m not really favoring this because not all filesystems support hardlinks and even less support hardlinks to folders to avoid recursion problems.
• I could bind mount the original folder to some temporary folder for the time ratarmount is running and then access the original folders over that temporary bind mount. However, I’m not sure how generic I can get this. This might be an option. Another problem with this is that mount --bind requires root, so I’d have to require something else like the bindfs package with the --no-allow-other option.

In all cases, I don’t think I’ll do the union mount as a default because too much could go wrong. I guess I’ll require the user to specify the folder twice if he wants to union mount it and also use it as the mount directory. However, I think I can detect this duplicate mention and then automatically add the -o nonempty option, so the user does not have to specify three things to get one result.~