Provided by:
unionfs-utils_1.0.14-1_i386 
NAME
Unionfs - a unification file system for Linux
SYNOPSIS
Unionfs is not a command, but rather a file system. This manual page
describes additional mount options that Unionfs supports.
mount -t unionfs -o
dirs=/branch1[=ro|=rw]:/branch2[=ro|=rw]:...:/branchN[=ro|=rw],imap=forwardmap:reversemap1:reversemap2:...:reversemapN,[copyup=preserve,currentuser,mounter]
none /mnt/unionfs
DESCRIPTION
dirs specifies a colon separated list of which directories compose the
union. Additionally, read-only or read-write permissions of the branch
can be specified by appending "=ro" or "=rw" to each directory.
Directories that come earlier in the list have a higher precedence than
those which come later.
debug specifies the FiST debugging level. 1 through 8 specify
individual log-levels. If debug is set to 11 through 18, the output
will include debug-10 and all lower levels. If you set this to a non-
zero value lots of output will be sent to the kernel ring buffer, some
of which may be sensitive. The default value for this option is 0 which
will produce no output.
delete controls how Unionfs deletes and renames objects. Possible
values are "all", and "whiteout" with the default behavior being all.
imap specifies a colon separated list of files that are used as the
inode map files. You should specify the forward map first, followed by
the reverse maps. The order of the reverse maps does not matter. The
default behavior for the imap option if left blank is to not use
persistent inode mappings.
copyup specifies which copy-up mode is used to provide copy-on-write
semantics in Unionfs. Possible values are preserve, currentuser, and
mounter. Preserve keeps the permissions in the higher-precedence
directory the same as in the lower-precedence directory. If
currentuser is selected, then the copied-up file will be owned by the
user whose actions initiated the copy-up operation. Finally, mounter
uses an owner and permission specified at mount time. The default
behavior for copyup is preserve.
copyupuid specifies the uid of the copied-up files. This has no default
behavior and must be set if copyup is set to the mounter option.
copyupgid specifies the gid of the copied-up files. This has no default
behavior and must be set if copyup is set to the mounter option.
copyupmode specifies the mode of the copied-up files. This has no
default behavior and must be set if copyup is set to the mounter
option.
AUTHORS
Charles Wright <cwright@cs.sunysb.edu>, Mohammad Zubair
<mzubair@ic.sunysb.edu>, Erez Zadok <ezk@cs.sunysb.edu>
SEE ALSO
unionctl(1), uniondbg(1), http://www.fsl.cs.sunysb.edu/