Run command in specific network Linux namespace (netns). It has the same logic as ip netns exec but in dedicated binary. It can be useful when you need to run commands as an unprivileged user with using capabilities:
# setcap cap_sys_admin+ep ./nsexec
It is possible to use custom configuration files (as using ip netns exec) for specific network namespace stored in /etc/netns/NAME/. For example, you can use custom resolv.conf for ns1 network namespace placing it as /etc/netns/ns1/resolv.conf.
Each execution creates new mount namespace for custom sysfs with actual information about network devices. If it is undesirable, you should use nsenter (1) to run a command with namespace(s) of the other process.