UNSHARE(1)                                User Commands                                UNSHARE(1)



NAME
       unshare - run program with some namespaces unshared from parent

SYNOPSIS
       unshare [options] program [arguments]

DESCRIPTION
       Unshares  the indicated namespaces from the parent process and then executes the specified
       program.  The namespaces to be unshared are indicated 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 for the shared flags).

              It's  recommended to use mount --make-rprivate or mount --make-rslave after unshare
              --mount to make sure that mountpoints in the new namespace are really unshared from
              the parental namespace.

       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 message  queues,  sema‐
              phore sets and shared memory segments.  (CLONE_NEWIPC flag)

       network namespace
              The process will have independent IPv4 and IPv6 stacks, IP routing 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   capabilities.
              (CLONE_NEWUSER flag)

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

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

       -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 options.

       -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.

       --mount-proc[=mountpoint]
              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 cre‐
              ating a new mount namespace since the /proc mount would otherwise mess up  existing
              programs  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 sophisti‐
              cated use cases, such as mapping multiple ranges of UIDs and GIDs.

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

BUGS
       None known so far.

AUTHOR
       Mikhail Gusarov <dottedmag AT dottedmag.net>

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



util-linux                                  July 2014                                  UNSHARE(1)