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)