Mount a directory to another location and alter permission bits.
bindfs is a FUSE filesystem for mounting a directory to another location, similarly to mount --bind. The permissions inside the mountpoint can be altered using various rules.
Here are some examples of what bindfs can do for you:
Make a directory read-only for non-root users.
bindfs --perms=a-w somedir somedir
Share a directory with some other users without modifying /etc/group.
bindfs --mirror-only=joe,bob,@wheel ~/some/dir shared
Make all new files uploaded to an FTP share owned by you and seen by everyone.
bindfs --create-for-user=me --create-with-perms=u+rw,a+rD /var/ftp/uploads /var/ftp/uploads
Make your website available to the webserver process read-only.
bindfs --force-user=www --perms=0000:u=rD ~/stuff/website ~/public_html
The corresponding /etc/fstab entry.
/home/bob/stuff/website /home/bob/public_html fuse.bindfs force-user=www,perms=0000:u+rD 0 0
bindfs is available through the software repositories of many Linux distributions, as well as MacPorts on OS X. Check there first unless there is a specific new feature that you need.
Download the latest source tarball here: bindfs-1.17.0.tar.gz.
Compile & install: ./configure && make && sudo make install.
There is an extensive HowTo on Ubuntu Forums.
bindfs is developed and tested primarily on Linux with FUSE 2 and 3, but it has been reported to work reasonably well on Mac OS X with osxfuse and on FreeBSD with fuse4bsd.
All FUSE filesystems necessarily incur a performance penalty in CPU time and memory consumption. If all you need is to make a directory read-only then mount --bind -r is more efficient.
bindfs was initially developed in 2006. I consider the program fairly feature-complete but I’ll still gladly fix bugs and add some small features as people suggest them.
Bug reports, pull requests, comments and ideas are very welcome. Developement takes place on GitHub. Please use the issue tracker.
--multithreaded.