UNIONFS(8)UNIONFS(8)NAME
Unionfs - a unification file system for Linux
SYNOPSISunionctl UNION ACTION [ OPTIONS ]
unionctl UNION --add [ --before BRANCH | --after BRANCH ] [ --mode
(rw|ro|nfsro) ] DIRECTORY
unionctl UNION --remove BRANCH
unionctl UNION --mode BRANCH (rw|ro|nfsro)
unionctl UNION --list
DESCRIPTIONunionctl is used to control a unionfs file system. The first argument
is a union, which is the mount point of unionfs, or any file within
unionfs. The second argument is an action. Currently unionctl sup‐
ports file actions: --add, --remove, --mode, --list and --query. Fur‐
ther arguments are action dependent.
When a branch is required as an argument, it can be specified in two
ways. The easiest way is to specify the path to the branch. If the
path is used multiple times in the union, the highest priority branch
will be used. A branch can also be specified as an index starting from
zero.
ACTIONS--add add a branch into a union. By default a read-write branch will
be added as the first component of the union.
The order of branches can be modified with --before and --after.
Each of these takes a single branch as an argument. If --before
is specified the new branch will be added before the specified
branch; and if --after is specified the new branch will be added
after the specified branch.
Finally, --mode will set the permissions on the new branch.
--mode requires one argument, which is "rw" for a read-write
branch, "ro" for a read-only branch and "nfsro" for read-only
access on NFS shares (see unionfs(4) for further information).
Note: The directory to add must be the last argument.
--remove
removes a branch from a union. Branches with open files can not
be removed.
--query option.
To remove a branch, unionctl performs an ioctl that operates on
a file descriptor. If the root directory is opened, then the
branch will necessarily be busy.
--mode sets the permissions of a branch. --mode requires two argu‐
ments, the first is the branch to operate on; and the second is
what mode to set. The allowed modes are "rw" for read-write
access, "ro" for read-only access and "nfsro" for read-only
access on NFS shares (see unionfs(4) for further information).
--list list branches within the union (and also their permissions).
--query
lists the branches where a given file exists. --query requires
one argument : the name of the file to be examined. The output
is a list of branches where the file exists and the permissions
of the branches.
AUTHORS
Charles Wright <cwright@cs.sunysb.edu>, Mohammad Zubair
<mzubair@ic.sunysb.edu>, Erez Zadok <ezk@cs.sunysb.edu>
SEE ALSOunionfs(4), uniondbg(8), http://unionfs.filesystems.org/
Linux January 2006 UNIONFS(8)
