通过系统PID获取内部docker PID

Question

After I use exec command inside docker container I can get the PID with exec inspect . The problem is that this ID is not local to the container but a system PID. So I would get something like 22620 while the PID inside docker container is 695 .

I know that docker uses process namespaces to isolate its processes. So I have tried to get the internal PID with cat /proc/22620/status | grep NSpid cat /proc/22620/status | grep NSpid . This indeed gave me the PID I was looking for:

NSpid: 22620 695

But I need to parse this string to get the PID. Is there a proper way to get the PID used by the docker container?

PS.

I need this process ID to kill the process started by other exec call. I cannot kill the system process as it is owned by root and I cannot use sudo.

Answer 1

Och. Use cut to filter a section from a line.

grep NSpid /proc/24918/status | cut -f3

Will give 695 from the example.