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UNSHARE(1)			 User Commands			    UNSHARE(1)

       unshare - run program with some namespaces unshared from parent

       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
	      Unshare the network namespace.

       -p, --pid
	      Unshare the pid namespace.  See also the --fork and --mount-proc

       -u, --uts
	      Unshare the UTS namespace.

       -U, --user
	      Unshare the user namespace.

       -f, --fork
	      Fork the specified program as a child process of unshare	rather
	      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.

       $ unshare --map-root-user --user sh -c whoami
	      Establish a user namespace as an unprivileged user with  a  root
	      user within it.

       unshare(2), clone(2), mount(8)

       None known so far.

       Mikhail Gusarov <dottedmag@dottedmag.net>

       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)