fuse-overlayfs(1)	    General Commands Manual	     fuse-overlayfs(1)



NAME
       fuse-overlayfs - overlayfs FUSE implementation



SYNOPSIS
       mounting
	   fuse-overlayfs [-f] [--debug] [-o OPTS] MOUNT_TARGET


       unmounting
	   fusermount -u mountpoint



DESCRIPTION
       fuse-overlayfs provides an overlayfs FUSE implementation so that it can
       be used since Linux 4.18 by unprivileged users in an user namespace.



OPTIONS
       --debug Enable debugging mode, can be very noisy.


       -o lowerdir=low1[:low2...] A list of directories separated by :.	 Their
       content is merged.


       -o upperdir=upperdir A directory merged on top of all the lowerdirs
       where all the changes done to the file system will be written.


       -o workdir=workdir A directory used internally by fuse-overlays, must
       be on the same file system as the upper dir.


       -o uidmapping=UID:MAPPED-UID:LEN[,UID2:MAPPED-UID2:LEN2] -o
       gidmapping=GID:MAPPED-GID:LEN[,GID2:MAPPED-GID2:LEN2] Specifies the
       dynamic UID/GID mapping used by fuse-overlayfs when reading/writing
       files to the system.


       The fuse-overlayfs dynamic mapping is an alternative and cheaper way to
       chown'ing the files on the host to accommodate the user namespace
       settings.


       It is useful to share the same storage among different user namespaces
       and counter effect the mapping done by the user namespace itself, and
       without requiring to chown the files.


       For example, given on the host two files like:


       $ stat -c %u:%g lower/a lower/b 0:0 1:1


       When we run in a user namespace with the following configuration: $ cat
       /proc/self/uid_map
		0	1000	      1
		1     110000	  65536


       We would see:


       $ stat -c %u:%g merged/a merged/b 65534:65534 65534:65534


       65534 is the overflow id used when the UID/GID is not known inside the
       user namespace.	This happens because both users 0:0 and 1:1 are not
       mapped.


       In the above example, if we mount the fuse-overlayfs file system using:
       -ouidmapping=0:1000:1:1:110000:65536,gidmapping=0:1000:1:1:110000:65536,
       which is the namespace configuration specified on a single line, we'd
       see from the same user namespace:


       $ stat -c %u:%g merged/a merged/b 0:0 1:1


       Those are the same IDs visible from outside the user namespace.


       -o squash_to_root Every file and directory is owned by the root user
       (0:0).


       -o squash_to_uid=uid -o squash_to_gid=gid Every file and directory is
       owned by the specified uid or gid.


       It has higher precedence over squash_to_root.


       -o static_nlink Set st_nlink to the static value 1 for all directories.


       This can be useful for higher latency file systems such as NFS, where
       counting the number of hard links for a directory with many files can
       be a slow operation. With this option enabled, the number of hard links
       reported when running stat for any directory is 1.


       -o noacl Disable ACL support in the FUSE file system.



SEE ALSO
       fuse(8), mount(8), user_namespaces(7)



AVAILABILITY
       The fuse-overlayfs command is available from
       https://github.com/containers/fuse-overlayfs under GNU GENERAL PUBLIC
       LICENSE Version 3 or later.

				 User Commands		     fuse-overlayfs(1)