| lxc-usernsexec(1) - phpMan
lxc-usernsexec(1) lxc-usernsexec(1)
NAME
lxc-usernsexec - Run a task as root in a new user namespace.
SYNOPSIS
lxc-usernsexec [-m uid-map] {-- command}
DESCRIPTION
lxc-usernsexec can be used to run a task as root in a new user namespace.
OPTIONS
-m uid-map
The uid map to use in the user namespace. Each map consists of four colon-separate
values. First a character 'u', 'g' or 'b' to specify whether this map pertains to
user ids, group ids, or both; next the first userid in the user namespace; next the
first userid as seen on the host; and finally the number of ids to be mapped.
More than one map can be specified. If no map is specified, then by default the
full uid and gid ranges granted by /etc/subuid and /etc/subgid will be mapped to
the uids and gids starting at 0 in the container.
Note that lxc-usernsexec always tries to setuid and setgid to 0 in the namespace.
Therefore uid 0 in the namespace must be mapped.
EXAMPLES
To spawn a shell with the full allotted subuids mapped into the container, use
lxc-usernsexec
To run a different shell than /bin/sh, use
lxc-usernsexec -- /bin/bash
If your user id is 1000, root in a container is mapped to 190000, and you wish to chown a
file you own to root in the container, you can use:
lxc-usernsexec -m b:0:1000:1 -m b:1:190000:1 -- /bin/chown 1:1 $file
This maps your userid to root in the user namespace, and 190000 to uid 1. Since root in
the user namespace is privileged over all userids mapped into the namespace, you are al‐
lowed to change the file ownership, which you could not do on the host using a simple
chown.
SEE ALSO
lxc(7), lxc-create(1), lxc-destroy(1), lxc-start(1), lxc-stop(1), lxc-execute(1), lxc-con‐
sole(1), lxc-monitor(1), lxc-wait(1), lxc-cgroup(1), lxc-ls(1), lxc-info(1), lxc-
freeze(1), lxc-unfreeze(1), lxc-attach(1), lxc.conf(5)
AUTHOR
Serge Hallyn <serge.hallyn AT ubuntu.com>
Sat Apr 29 06:45:43 UTC 2017 lxc-usernsexec(1)
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