Map PID to namespace

this script doing map pid to namespace

example, I doing unshare -r --net bash, and get the pid via echo $$. now I want map this pid into namespace that be executed using ip link set <IFACE> netns <HERE_OUR_NS>

map2ns.sh

jump_mk_netns() {
        mkdir -p /var/run/netns
}

map_pid2ns() {
        pid=$1
        nsname=$2

        ln -s /proc/$pid/ns/net /var/run/netns/$nsname
}

echo "mapping $1 into $2"

if [[ -d "/var/run/netns" ]]; then
        echo "netns detected"
        map_pid2ns $1 $2
else
        jump_mk_netns
        map_pid2ns $1 $2
fi