UNSHARE(1) manual page
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unshare - run program with some namespaces unshared from parent
unshare
[options] program [arguments]
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, semaphore 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.
- -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 creating 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 network 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.
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/.
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