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A filtered read-only filesystem for FUSE
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cmake Install config files only if they don't already exist Nov 15, 2018
test document how to handle files that mimic special file type filters Sep 13, 2018
.gitattributes Updated instructions for multiple mount points Dec 20, 2014
NEWS Seems to build properly with autoconf/automake Apr 2, 2009

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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:


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


mkdir build
cd build
cmake ..
sudo make install

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

brew install rofs-filtered 


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]
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