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.TH NSENTER 1 "June 2013" "util-linux" "User Commands"
.SH NAME
nsenter \- run program with namespaces of other processes
.SH SYNOPSIS
.B nsenter
[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 the rest of the system
.RB ( CLONE_\:NEWNS
flag), except for filesystems which are explicitly marked as shared (with
\fBmount --make-\:shared\fP; see \fI/proc\:/self\:/mountinfo\fP for the
\fBshared\fP flag).
.TP
.B UTS namespace
Setting hostname or domainname will not affect the rest of the system.
.RB ( CLONE_\:NEWUTS
flag)
.TP
.B IPC namespace
The process will have an independent namespace for System V message queues,
semaphore sets and shared memory segments.
.RB ( CLONE_\:NEWIPC
flag)
.TP
.B network namespace
The 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 \fB\-\-no\-fork\fP is used, the new program will be exec'ed without forking.
.TP
.B user namespace
The process will have a distinct set of UIDs, GIDs and capabilities.
.RB ( CLONE_\:NEWUSER
flag)
.TP
See \fBclone\fP(2) for the exact semantics of the flags.
.TP
If \fIprogram\fP is not given, then ``${SHELL}'' is run (default: /bin\:/sh).
.SH OPTIONS
.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. See also the \fB\-\-setuid\fR and \fB\-\-setgid\fR options.
.TP
\fB\-G\fR, \fB\-\-setgid\fR \fIgid\fR
Set the group ID which will be used in the entered namespace and drop
supplementary groups.
.BR nsenter (1)
always sets GID for user namespaces, the default is 0.
.TP
\fB\-S\fR, \fB\-\-setuid\fR \fIuid\fR
Set the user ID which will be used in the entered namespace.
.BR nsenter (1)
always sets UID for user namespaces, the default is 0.
.TP
\fB\-\-preserve\-credentials\fR
Don't modify UID and GID when enter user namespace. The default is to
drops supplementary groups and sets GID and UID to 0.
.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, \fBnsenter\fP calls \fBfork\fP before calling \fBexec\fP so that
any children will also 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
Display help text and exit.
.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 .
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