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, 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.
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 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.
SEE ALSO¶
unshare(2),
clone(2),
mount(8)
BUGS¶
None known so far.
AUTHOR¶
Mikhail Gusarov <dottedmag@dottedmag.net>
AVAILABILITY¶
The unshare command is part of the util-linux package and is available from
ftp://ftp.kernel.org/pub/linux/utils/util-linux/.