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       unshare [options] program [arguments]


       Unshares the indicated namespaces from the parent process and then exe-
       cutes the specified program.  The namespaces to be unshared  are  indi-
       cated via options.  Unshareable namespaces are:

       mount namespace
              Mounting  and unmounting filesystems will not affect the rest of
              the system (CLONE_NEWNS flag), except for filesystems which  are
              explicitly  marked  as  shared  (with  mount  --make-shared; see
              /proc/self/mountinfo or findmnt -o+PROPAGATION  for  the  shared

              unshare  automatically  sets  propagation  to private in the new
              mount namespace to make sure that the new  namespace  is  really
              unshared. This feature is possible to disable by option --propa-
              gation unchanged.  Note that private is the kernel default.

       UTS namespace
              Setting hostname or domainname will not affect the rest  of  the
              system.  (CLONE_NEWUTS flag)

       IPC namespace
              The process will have an independent namespace for System V mes-
              sage  queues,  semaphore  sets  and  shared   memory   segments.
              (CLONE_NEWIPC flag)

       network namespace
              The process will have independent IPv4 and IPv6 stacks, IP rout-
              ing tables, firewall rules,  the  /proc/net  and  /sys/class/net
              directory trees, sockets, etc.  (CLONE_NEWNET flag)

       pid namespace
              Children  will  have  a  distinct set of PID to process mappings
              from their parent.  (CLONE_NEWPID flag)

       user namespace
              The process will have a distinct set of UIDs, GIDs and capabili-
              ties.  (CLONE_NEWUSER flag)

       See clone(2) for the exact semantics of the flags.


       -i, --ipc
              Unshare the IPC namespace.

       -m, --mount
              Unshare the mount namespace.

       -n, --net
              than  running  it  directly.  This is useful when creating a new
              pid namespace.

              Just before running the program, mount the  proc  filesystem  at
              mountpoint  (default  is /proc).  This is useful when creating a
              new pid namespace.  It also implies creating a new mount  names-
              pace since the /proc mount would otherwise mess up existing pro-
              grams on the system.  The  new  proc  filesystem  is  explicitly
              mounted as private (by MS_PRIVATE|MS_REC).

       -r, --map-root-user
              Run  the program only after the current effective user and group
              IDs have been mapped to the superuser UID and GID in  the  newly
              created  user namespace.  This makes it possible to conveniently
              gain capabilities needed to manage various aspects of the  newly
              created  namespaces  (such as configuring interfaces in the net-
              work namespace or mounting filesystems in the  mount  namespace)
              even  when  run unprivileged.  As a mere convenience feature, it
              does not support more sophisticated use cases, such  as  mapping
              multiple  ranges  of  UIDs and GIDs.  This option implies --set-

       --propagation private|shared|slave|unchanged
              Recursively sets mount propagation flag in the new mount  names-
              pace.  The  default  is  to set the propagation to private, this
              feature is  possible  to  disable  by  unchanged  argument.  The
              options  is  silently  ignored when mount namespace (--mount) is
              not requested.

       --setgroups allow|deny
              Allow or deny setgroups(2) syscall in user namespaces.

              setgroups(2) is only callable with CAP_SETGID and CAP_SETGID  in
              a user namespace (since Linux 3.19) does not give you permission
              to call setgroups(2) until after GID map has been set.  The  GID
              map is writable by root when setgroups(2) is enabled and GID map
              becomes writable by unprivileged processes when setgroups(2)  is
              permanently disabled.

       -V, --version
              Display version information and exit.

       -h, --help
              Display help text and exit.


       # unshare --fork --pid --mount-proc readlink /proc/self
              Establish  a  PID  namespace,  ensure  we're PID 1 in it against
              newly mounted procfs instance.


       The  unshare command is part of the util-linux package and is available
       from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.

util-linux July 2014 UNSHARE(1)

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