.TH NSENTER 1 "January 2013" "util-linux" "User Commands"
.SH NAME
nsenter \- run program with namespaces of other processes
.SH SYNOPSIS
.B nsenter
.RI [ options ]
.RI [ program ]
.RI [ arguments ]
.SH DESCRIPTION
Enters the namespaces of one or more other processes and then executes the specified
program.  Enterable namespaces are:
.TP
.B mount namespace
mounting and unmounting filesystems will not affect rest of the system
.RB ( CLONE_\:NEWNS
flag), except for filesystems which are explicitly marked as shared (by mount
--make-\:shared).  See /proc\:/self\:/mountinfo for the shared flag.
.TP
.B UTS namespace
setting hostname, domainname will not affect rest of the system
.RB ( CLONE_\:NEWUTS
flag).
.TP
.B IPC namespace
process will have independent namespace for System V message queues, semaphore
sets and shared memory segments
.RB ( CLONE_\:NEWIPC
flag).
.TP
.B network namespace
process will have independent IPv4 and IPv6 stacks, IP routing tables, firewall
rules, the
.I /proc\:/net
and
.I /sys\:/class\:/net
directory trees, sockets etc.
.RB ( CLONE_\:NEWNET
flag).
.TP
.B PID namespace
children will have a set of PID to process mappings separate from the
.B nsenter
process
.RB ( CLONE_\:NEWPID
flag).
.B 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.
.TP
.B user namespace
process will have distinct set of UIDs, GIDs and capabilities
.RB ( CLONE_\:NEWUSER
flag).
.TP
See the
.BR clone (2)
for exact semantics of the flags.
.TP
If program is not given, run ``${SHELL}'' (default: /bin\:/sh).

.SH OPTIONS
Argument with square brakets, such as [\fIfile\fR], means optional argument.
Command line syntax to specify optional argument \-\-mount=/path\:/to\:/file.
Please notice the equals sign.
.TP
\fB\-t\fR, \fB\-\-target\fR \fIpid\fP
Specify a target process to get contexts from.  The paths to the contexts
specified by
.I pid
are:
.RS
.PD 0
.IP "" 20
.TP
/proc/\fIpid\fR/ns/mnt
the mount namespace
.TP
/proc/\fIpid\fR/ns/uts
the UTS namespace
.TP
/proc/\fIpid\fR/ns/ipc
the IPC namespace
.TP
/proc/\fIpid\fR/ns/net
the network namespace
.TP
/proc/\fIpid\fR/ns/pid
the PID namespace
.TP
/proc/\fIpid\fR/ns/user
the user namespace
.TP
/proc/\fIpid\fR/root
the root directory
.TP
/proc/\fIpid\fR/cwd
the working directory respectively
.PD
.RE
.TP
\fB\-m\fR, \fB\-\-mount\fR [\fIfile\fR]
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.
.TP
\fB\-u\fR, \fB\-\-uts\fR [\fIfile\fR]
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.
.TP
\fB\-i\fR, \fB\-\-ipc\fR [\fIfile\fR]
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.
.TP
\fB\-n\fR, \fB\-\-net\fR [\fIfile\fR]
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.
.TP
\fB\-p\fR, \fB\-\-pid\fR [\fIfile\fR]
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.
.TP
\fB\-U\fR, \fB\-\-user\fR [\fIfile\fR]
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.
.TP
\fB\-r\fR, \fB\-\-root\fR [\fIdirectory\fR]
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.
.TP
\fB\-w\fR, \fB\-\-wd\fR [\fIdirectory\fR]
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.
.TP
\fB\-F\fR, \fB\-\-no-fork\fR
Do not fork before exec'ing the specified program.  By default when entering a
pid namespace enter calls fork before calling exec so that the children will be
in the newly entered pid namespace.
.TP
\fB\-V\fR, \fB\-\-version\fR
Display version information and exit.
.TP
\fB\-h\fR, \fB\-\-help\fR
Print a help message.
.SH SEE ALSO
.BR setns (2),
.BR clone (2)
.SH AUTHOR
.MT ebiederm@xmission.com
Eric Biederman
.ME
.SH AVAILABILITY
The nsenter command is part of the util-linux package and is available from
.UR ftp://\:ftp.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
Linux Kernel Archive
.UE .