nsenter man page

nsenter — run program with namespaces of other processes

Synopsis

nsenter [options] [program [arguments]]

Description

Enters the namespaces of one or more other processes and then executes the specified program. Enterable 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 flag).
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 set of PID to process mappings separate from the nsenter process (CLONE_NEWPID flag). 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.
user namespace
The process will have a distinct set of UIDs, GIDs and capabilities. (CLONE_NEWUSER flag)
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. (CLONE_NEWCGROUP flag)

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

If program is not given, then “${SHELL}” is run (default: /bin/sh).

Options

-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/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.
-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.
-G, --setgid gid
Set the group ID which will be used in the entered namespace and drop supplementary groups. nsenter(1) always sets GID for user namespaces, the default is 0.
-S, --setuid uid
Set the user ID which will be used in the entered namespace. nsenter(1) always sets UID for user namespaces, the default is 0.
--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.
-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.
-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.)
-V, --version
Display version information and exit.
-h, --help
Display help text and exit.

See Also

setns(2), clone(2)

Authors

Eric Biederman
Karel Zak

Availability

The nsenter command is part of the util-linux package and is available from Linux Kernel Archive.

Referenced By

lsns(8), namespaces(7), unshare(1).

June 2013 util-linux User Commands