This FUSE file system allows the user to mount a directory tree as read-only and filter the files shown in the read-only directory tree based on regular expressions found in the rofs-filtered.rc configuration file. See the rofs-filtered.rc file for more details.

What's the use of such a file system? Here are two use cases:

• Say you have a ton of *.flac music files, along with the transcoded *.mp3 files in the same directory tree structure. Maybe you want to show only one of the formats to music players that can play both flac and mp3 so that the songs don't show up twice. You might also want to show only mp3 files to players that don't understand the flac format.

• If you take pictures with your DSLR in raw camera format, you might want to allow an application RO access to only the JPG version of the images.

Based on: ROFS - The read-only filesystem for FUSE.

Get the latest version from: https://github.com/gburca/rofs-filtered

Dependencies:

• libfuse2
• libfuse-dev
• fuse
  • Version 2.5 or later of FUSE is required.

Building:

mkdir build
cd build
cmake ..
make
sudo make install

On Mac OS X 10.10 Yosemite or later you can use Homebrew to install:

brew install rofs-filtered 

Using:

rofs-filtered --help

• The rofs-filtered.rc file contains instructions on how to configure the filtering. This file is installed by default in /usr/local/etc.

• Mount a directory tree by adding a similar line to /etc/fstab:

/usr/local/bin/rofs-filtered	/the/read/write/device /the/read/only/mount/point fuse defaults,allow_other 0 0

• If you need to have different mount points, each with its own filter rules, you can use an alternative syntax in /etc/fstab:

/usr/local/bin/rofs-filtered	/the/ro/mount/point1	fuse	defaults,allow_other,source=/the/rw/device1,config=/etc/filter1.rc
/usr/local/bin/rofs-filtered	/the/ro/mount/point2	fuse	defaults,allow_other,source=/the/rw/device2,config=/etc/filter2.rc

• The rofs-filtered executable can also be called directly:

rofs-filtered <Filtered-Path> -o source=<RW-Path> [-o config=/etc/filter1.rc] [FUSE options]

• To unmount use one of these two commands:

fusermount -u /the/read/only/mount/point 
# OR
umount /the/read/only/mount/point

• On some systems, the user will need to be in the "fuse" UNIX group.

• The configuration file normally specifies what files should be filtered out. When the "invert" option is used, only files that match the RegEx will be shown. This can be tricky to configure. See the rofs-filtered-invert.rc file for some tips. The "invert" option can be specified in fstab or on the command line respectively as follows:

/usr/local/bin/rofs-filtered	/the/ro/mount/point1	fuse	defaults,allow_other,source=/the/rw/device1,config=/etc/filter1.rc,invert

rofs-filtered <Filtered-Path> -o source=<RW-Path> -o invert [-o config=/etc/filter1.rc] [FUSE options]

• To debug and see verbose logging:

rofs-filtered ... -o debug -f

Tips

• Consider adding fuse.rofs-filtered to the PRUNEFS list in /etc/updatedb.conf so you don't see duplicates when looking up files with locate.

• If your RW directory has a symbolic link to some other place (outside the RW path), rofs-filtered will not apply to that other directory. Following the example above, say you're trying to hide the flac files in /music/files, but you have a link from /music/files/more to /overflow/path. When you mount /music/files, all the flac files are properly filtered, but you'll notice that a file such as /overflow/path/foo.flac still shows up. The solution: instead of using symbolic links, use mount with the --bind option to mount /overflow/path at /music/files/more.