NAME

       nsenter - run program in different namespaces

SYNOPSIS

       nsenter [options] [program [arguments]]

DESCRIPTION

       The nsenter command executes program in the namespace(s) that are specified in the
       command-line options (described below). If program is not given, then "${SHELL}" is run
       (default: /bin/sh).

       Enterable namespaces are:

       mount namespace
           Mounting and unmounting filesystems will not affect the rest of the system, except for
           filesystems which are explicitly marked as shared (with mount --make-shared; see
           /proc/self/mountinfo for the shared flag). For further details, see
           mount_namespaces(7) and the discussion of the CLONE_NEWNS flag in clone(2).

       UTS namespace
           Setting hostname or domainname will not affect the rest of the system. For further
           details, see uts_namespaces(7).

       IPC namespace
           The process will have an independent namespace for POSIX message queues as well as
           System V message queues, semaphore sets and shared memory segments. For further
           details, see ipc_namespaces(7).

       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. For further
           details, see network_namespaces(7).

       PID namespace
           Children will have a set of PID to process mappings separate from the nsenter process.
           nsenter will fork by default if changing the PID namespace, so that the new program
           and its children share the same PID namespace and are visible to each other. If
           --no-fork is used, the new program will be exec’ed without forking. For further
           details, see pid_namespaces(7).

       user namespace
           The process will have a distinct set of UIDs, GIDs and capabilities. For further
           details, see user_namespaces(7).

       cgroup namespace
           The process will have a virtualized view of /proc/self/cgroup, and new cgroup mounts
           will be rooted at the namespace cgroup root. For further details, see
           cgroup_namespaces(7).

       time namespace
           The process can have a distinct view of CLOCK_MONOTONIC and/or CLOCK_BOOTTIME which
           can be changed using /proc/self/timens_offsets. For further details, see
           time_namespaces(7).

OPTIONS

       Various of the options below that relate to namespaces take an optional file argument.
       This should be one of the /proc/[pid]/ns/* files described in namespaces(7), or the
       pathname of a bind mount that was created on one of those files.

       -a, --all
           Enter all namespaces of the target process by the default /proc/[pid]/ns/* namespace
           paths. The default paths to the target process namespaces may be overwritten by
           namespace specific options (e.g., --all --mount=[path]).

           The user namespace will be ignored if the same as the caller’s current user namespace.
           It prevents a caller that has dropped capabilities from regaining those capabilities
           via a call to setns(). See setns(2) for more details.

       -t, --target PID
           Specify a target process to get contexts from. The paths to the contexts specified by
           pid are:

           /proc/pid/ns/mnt
               the mount namespace

           /proc/pid/ns/uts
               the UTS namespace

           /proc/pid/ns/ipc
               the IPC namespace

           /proc/pid/ns/net
               the network namespace

           /proc/pid/ns/pid
               the PID namespace

           /proc/pid/ns/user
               the user namespace

           /proc/pid/ns/cgroup
               the cgroup namespace

           /proc/pid/ns/time
               the time namespace

           /proc/pid/root
               the root directory

           /proc/pid/cwd
               the working directory respectively

       -m, --mount[=file]
           Enter the mount namespace. If no file is specified, enter the mount namespace of the
           target process. If file is specified, enter the mount namespace specified by file.

       -u, --uts[=file]
           Enter the UTS namespace. If no file is specified, enter the UTS namespace of the
           target process. If file is specified, enter the UTS namespace specified by file.

       -i, --ipc[=file]
           Enter the IPC namespace. If no file is specified, enter the IPC namespace of the
           target process. If file is specified, enter the IPC namespace specified by file.

       -n, --net[=file]
           Enter the network namespace. If no file is specified, enter the network namespace of
           the target process. If file is specified, enter the network namespace specified by
           file.

       -p, --pid[=file]
           Enter the PID namespace. If no file is specified, enter the PID namespace of the
           target process. If file is specified, enter the PID namespace specified by file.

       -U, --user[=file]
           Enter the user namespace. If no file is specified, enter the user namespace of the
           target process. If file is specified, enter the user namespace specified by file. See
           also the --setuid and --setgid options.

       --user-parent
           Enter the parent user namespace. Parent user namespace will be acquired from any other
           enabled namespace. If combined with --user option the parent user namespace will be
           fetched from the user namespace and replace it.

       -C, --cgroup[=file]
           Enter the cgroup namespace. If no file is specified, enter the cgroup namespace of the
           target process. If file is specified, enter the cgroup namespace specified by file.

       -T, --time[=file]
           Enter the time namespace. If no file is specified, enter the time namespace of the
           target process. If file is specified, enter the time namespace specified by file.

       -G, --setgid gid
           Set the group ID which will be used in the entered namespace and drop supplementary
           groups. nsenter always sets GID for user namespaces, the default is 0. If the argument
           "follow" is specified the GID of the target process is used.

       -S, --setuid uid
           Set the user ID which will be used in the entered namespace. nsenter always sets UID
           for user namespaces, the default is 0. If the argument "follow" is specified the UID
           of the target process is used.

       --keep-caps
           When the --user option is given, ensure that capabilities granted in the user
           namespace are preserved in the child process.

       --preserve-credentials
           Don’t modify UID and GID when enter user namespace. The default is to drops
           supplementary groups and sets GID and UID to 0.

       -r, --root[=directory]
           Set the root directory. If no directory is specified, set the root directory to the
           root directory of the target process. If directory is specified, set the root
           directory to the specified directory. The specified directory is open before it
           switches to the requested namespaces.

       -w, --wd[=directory]
           Set the working directory. If no directory is specified, set the working directory to
           the working directory of the target process. If directory is specified, set the
           working directory to the specified directory. The specified directory is open before
           it switches to the requested namespaces, it means the specified directory works as
           "tunnel" to the current namespace. See also --wdns.

       -W, --wdns[=directory]
           Set the working directory. The directory is open after switch to the requested
           namespaces and after chroot(2) call. The options --wd and --wdns are mutually
           exclusive.

       -e, --env
           Pass environment variables from the target process to the new process being created.
           If this option is not provided, the environment variables will remain the same as in
           the current namespace..

       -F, --no-fork
           Do not fork before exec’ing the specified program. By default, when entering a PID
           namespace, nsenter calls fork before calling exec so that any children will also be in
           the newly entered PID namespace.

       -Z, --follow-context
           Set the SELinux security context used for executing a new process according to already
           running process specified by --target PID. (The util-linux has to be compiled with
           SELinux support otherwise the option is unavailable.)

       -c, --join-cgroup
           Add the initiated process to the cgroup of the target process.

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

       -V, --version
           Print version and exit.

NOTES

       The --user-parent option requires Linux 4.9 or higher, older kernels will raise
       inappropriate ioctl for device error.

AUTHORS

       Eric Biederman <biederm@xmission.com>, Karel Zak <kzak@redhat.com>

SEE ALSO

       clone(2), setns(2), namespaces(7)

REPORTING BUGS

       For bug reports, use the issue tracker at https://github.com/util-linux/util-linux/issues.

AVAILABILITY

       The nsenter command is part of the util-linux package which can be downloaded from Linux
       Kernel Archive <https://www.kernel.org/pub/linux/utils/util-linux/>.