title: Can't send USR2 to nginx in docker
body: <p>I am trying to send USR2 signal to nginx which present in /usr/sbin of a linux docker container hosted on windows. This gives no error, but at the same time new nginx master is not spawned.</p>
  <p>At the same time sending a QUIT signal to the same nginx works completely fine and I have verified that.</p>
  <p>However, if I copy the same nginx binary file to a directory which is present on host(windows) and run it and then send a USR2 signal, it works completely fine. I have verified two running masters as well as two files /run/nginx.pid, /run/nginx.pid.oldbin .</p>
  <p>I am not able to figure out why I am not able to send a USR2 signal to a process whose binary is not present in host (but able to send a QUIT signal). I have also verified that SIGUSR2 exists in kill -l command.</p>
  <p>In an actual Linux machine sending usr2 to process run by /usr/sbin/nginx works just fine.</p>