sys-utils/nsenter.1

   1 .TH NSENTER 1 "June 2013" "util-linux" "User Commands"
   2 .SH NAME
   3 nsenter \- run program with namespaces of other processes
   4 .SH SYNOPSIS
   5 .B nsenter
   6 [options]
   7 .RI [ program
   8 .RI [ arguments ]]
   9 .SH DESCRIPTION
  10 Enters the namespaces of one or more other processes and then executes the specified
  11 \fIprogram\fP. If \fIprogram\fP is not given, then ``${SHELL}'' is run (default: /bin\:/sh).
  12 .PP
  13 Enterable namespaces are:
  14 .TP
  15 .B mount namespace
  16 Mounting and unmounting filesystems will not affect the rest of the system,
  17 except for filesystems which are explicitly marked as shared (with
  18 \fBmount --make-\:shared\fP; see \fI/proc\:/self\:/mountinfo\fP for the
  19 \fBshared\fP flag).
  20 For further details, see
  21 .BR mount_namespaces (7)
  22 and the discussion of the
  23 .B CLONE_NEWNS
  24 flag in
  25 .BR clone (2).
  26 .TP
  27 .B UTS namespace
  28 Setting hostname or domainname will not affect the rest of the system.
  29 For further details, see
  30 .BR uts_namespaces (7)
  31 and the discussion of the
  32 .B CLONE_NEWUTS
  33 flag in
  34 .BR clone (2).
  35 .TP
  36 .B IPC namespace
  37 The process will have an independent namespace for POSIX message queues
  38 as well as System V message queues,
  39 semaphore sets and shared memory segments.
  40 For further details, see
  41 .BR ipc_namespaces (7)
  42 and the discussion of the
  43 .B CLONE_NEWIPC
  44 flag in
  45 .BR clone (2).
  46 .TP
  47 .B network namespace
  48 The process will have independent IPv4 and IPv6 stacks, IP routing tables,
  49 firewall rules, the
  50 .I /proc\:/net
  51 and
  52 .I /sys\:/class\:/net
  53 directory trees, sockets, etc.
  54 For further details, see
  55 .BR network_namespaces (7)
  56 and the discussion of the
  57 .B CLONE_NEWNET
  58 flag in
  59 .BR clone (2).
  60 .TP
  61 .B PID namespace
  62 Children will have a set of PID to process mappings separate from the
  63 .B nsenter
  64 process.
  65 .B nsenter
  66 will fork by default if changing the PID namespace, so that the new program
  67 and its children share the same PID namespace and are visible to each other.
  68 If \fB\-\-no\-fork\fP is used, the new program will be exec'ed without forking.
  69 For further details, see
  70 .BR pid_namespaces (7)
  71 and
  72 the discussion of the
  73 .B CLONE_NEWPID
  74 flag in
  75 .BR clone (2).
  76 .TP
  77 .B user namespace
  78 The process will have a distinct set of UIDs, GIDs and capabilities.
  79 For further details, see
  80 .BR user_namespaces (7)
  81 and the discussion of the
  82 .B CLONE_NEWUSER
  83 flag in
  84 .BR clone (2).
  85 .TP
  86 .B cgroup namespace
  87 The process will have a virtualized view of \fI/proc\:/self\:/cgroup\fP, and new
  88 cgroup mounts will be rooted at the namespace cgroup root.
  89 For further details, see
  90 .BR cgroup_namespaces (7)
  91 and the discussion of the
  92 .B CLONE_NEWCGROUP
  93 flag in
  94 .BR clone (2).
  95 .TP
  96 .B time namespace
  97 The process can have a distinct view of
  98 .B CLOCK_MONOTONIC
  99 and/or
 100 .B CLOCK_BOOTTIME
 101 which can be changed using \fI/proc/self/timens_offsets\fP.
 102 For further details, see
 103 .BR time_namespaces (7).
 104 .TP
 105 See \fBclone\fP(2) for the exact semantics of the flags.
 106 .SH OPTIONS
 107 Various of the options below that relate to namespaces take an optional
 108 .I file
 109 argument.
 110 This should be one of the
 111 .I /proc/[pid]/ns/*
 112 files described in
 113 .BR namespaces (7).
 114 .TP
 115 \fB\-a\fR, \fB\-\-all\fR
 116 Enter all namespaces of the target process by the default
 117 .I /proc/[pid]/ns/*
 118 namespace paths. The default paths to the target process namespaces may be
 119 overwritten by namespace specific options (e.g., --all --mount=[path]).
 120
 121 The user namespace will be ignored if the same as the caller's current user
 122 namespace. It prevents a caller that has dropped capabilities from regaining
 123 those capabilities via a call to setns().  See
 124 .BR setns (2)
 125 for more details.
 126 .TP
 127 \fB\-t\fR, \fB\-\-target\fR \fIpid\fP
 128 Specify a target process to get contexts from.  The paths to the contexts
 129 specified by
 130 .I pid
 131 are:
 132 .RS
 133 .PD 0
 134 .IP "" 20
 135 .TP
 136 /proc/\fIpid\fR/ns/mnt
 137 the mount namespace
 138 .TP
 139 /proc/\fIpid\fR/ns/uts
 140 the UTS namespace
 141 .TP
 142 /proc/\fIpid\fR/ns/ipc
 143 the IPC namespace
 144 .TP
 145 /proc/\fIpid\fR/ns/net
 146 the network namespace
 147 .TP
 148 /proc/\fIpid\fR/ns/pid
 149 the PID namespace
 150 .TP
 151 /proc/\fIpid\fR/ns/user
 152 the user namespace
 153 .TP
 154 /proc/\fIpid\fR/ns/cgroup
 155 the cgroup namespace
 156 .TP
 157 /proc/\fIpid\fR/ns/time
 158 the time namespace
 159 .TP
 160 /proc/\fIpid\fR/root
 161 the root directory
 162 .TP
 163 /proc/\fIpid\fR/cwd
 164 the working directory respectively
 165 .PD
 166 .RE
 167 .TP
 168 \fB\-m\fR, \fB\-\-mount\fR[=\fIfile\fR]
 169 Enter the mount namespace.  If no file is specified, enter the mount namespace
 170 of the target process.
 171 If
 172 .I file
 173 is specified, enter the mount namespace
 174 specified by
 175 .IR file .
 176 .TP
 177 \fB\-u\fR, \fB\-\-uts\fR[=\fIfile\fR]
 178 Enter the UTS namespace.  If no file is specified, enter the UTS namespace of
 179 the target process.
 180 If
 181 .I file
 182 is specified, enter the UTS namespace specified by
 183 .IR file .
 184 .TP
 185 \fB\-i\fR, \fB\-\-ipc\fR[=\fIfile\fR]
 186 Enter the IPC namespace.  If no file is specified, enter the IPC namespace of
 187 the target process.
 188 If
 189 .I file
 190 is specified, enter the IPC namespace specified by
 191 .IR file .
 192 .TP
 193 \fB\-n\fR, \fB\-\-net\fR[=\fIfile\fR]
 194 Enter the network namespace.  If no file is specified, enter the network
 195 namespace of the target process.
 196 If
 197 .I file
 198 is specified, enter the network namespace specified by
 199 .IR file .
 200 .TP
 201 \fB\-p\fR, \fB\-\-pid\fR[=\fIfile\fR]
 202 Enter the PID namespace.  If no file is specified, enter the PID namespace of
 203 the target process.
 204 If
 205 .I file
 206 is specified, enter the PID namespace specified by
 207 .IR file .
 208 .TP
 209 \fB\-U\fR, \fB\-\-user\fR[=\fIfile\fR]
 210 Enter the user namespace.  If no file is specified, enter the user namespace of
 211 the target process.
 212 If
 213 .I file
 214 is specified, enter the user namespace specified by
 215 .IR file .
 216 See also the \fB\-\-setuid\fR and \fB\-\-setgid\fR options.
 217 .TP
 218 \fB\-C\fR, \fB\-\-cgroup\fR[=\fIfile\fR]
 219 Enter the cgroup namespace.  If no file is specified, enter the cgroup namespace of
 220 the target process.
 221 If
 222 .I file
 223 is specified, enter the cgroup namespace specified by
 224 .IR file .
 225 .TP
 226 \fB\-T\fR, \fB\-\-time\fR[=\fIfile\fR]
 227 Enter the time namespace.  If no file is specified, enter the time namespace of
 228 the target process.
 229 If
 230 .I file
 231 is specified, enter the time namespace specified by
 232 .IR file .
 233 .TP
 234 \fB\-G\fR, \fB\-\-setgid\fR \fIgid\fR
 235 Set the group ID which will be used in the entered namespace and drop
 236 supplementary groups.
 237 .BR nsenter (1)
 238 always sets GID for user namespaces, the default is 0.
 239 .TP
 240 \fB\-S\fR, \fB\-\-setuid\fR \fIuid\fR
 241 Set the user ID which will be used in the entered namespace.
 242 .BR nsenter (1)
 243 always sets UID for user namespaces, the default is 0.
 244 .TP
 245 \fB\-\-preserve\-credentials\fR
 246 Don't modify UID and GID when enter user namespace. The default is to
 247 drops supplementary groups and sets GID and UID to 0.
 248 .TP
 249 \fB\-r\fR, \fB\-\-root\fR[=\fIdirectory\fR]
 250 Set the root directory.  If no directory is specified, set the root directory to
 251 the root directory of the target process.  If directory is specified, set the
 252 root directory to the specified directory.
 253 .TP
 254 \fB\-w\fR, \fB\-\-wd\fR[=\fIdirectory\fR]
 255 Set the working directory.  If no directory is specified, set the working
 256 directory to the working directory of the target process.  If directory is
 257 specified, set the working directory to the specified directory.
 258 .TP
 259 \fB\-F\fR, \fB\-\-no\-fork\fR
 260 Do not fork before exec'ing the specified program.  By default, when entering a
 261 PID namespace, \fBnsenter\fP calls \fBfork\fP before calling \fBexec\fP so that
 262 any children will also be in the newly entered PID namespace.
 263 .TP
 264 \fB\-Z\fR, \fB\-\-follow\-context\fR
 265 Set the SELinux security context used for executing a new process according to
 266 already running process specified by \fB\-\-target\fR PID. (The util-linux has
 267 to be compiled with SELinux support otherwise the option is unavailable.)
 268 .TP
 269 \fB\-V\fR, \fB\-\-version\fR
 270 Display version information and exit.
 271 .TP
 272 \fB\-h\fR, \fB\-\-help\fR
 273 Display help text and exit.
 274 .SH AUTHORS
 275 .UR biederm@xmission.com
 276 Eric Biederman
 277 .UE
 278 .br
 279 .UR kzak@redhat.com
 280 Karel Zak
 281 .UE
 282 .SH SEE ALSO
 283 .BR clone (2),
 284 .BR setns (2),
 285 .BR namespaces (7)
 286 .SH AVAILABILITY
 287 The nsenter command is part of the util-linux package and is available from
 288 .UR https://\:www.kernel.org\:/pub\:/linux\:/utils\:/util-linux/
 289 Linux Kernel Archive
 290 .UE .