Root PID of Docker container

Question

How can I find the external PID of the root PID inside a Docker container - that is, the one that has PID 1 inside the container? docker ps doesn't seem to display that information.

Answer 1

一种可能的方法是：

docker inspect -f '{{ .State.Pid }}' $CONTAINER_ID

Answer 2

请试试：

docker inspect -f '{{.State.Pid}}' $(docker ps -q) 

Answer 3

Here is a POSIX shell function that captures the PID for a given container.

pid_for_container() {
  ps -C lxc-start -o pid= -o args= | fgrep -- " -n $1" | cut -d' ' -f1
}

It is a minimal (I hope) pipeline for this purpose, using the cheapest possible ( fgrep instead of grep , cut instead of awk ) commands.