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  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 accomodate 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.

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)