I stopped httpd processes on a centos 7.6 machine using kill -STOP command and the processes show up as stopped in top output. I tried to telnet the webserver's IP on port 80 and was able to do so fine.

I am trying to understand what exactly stopping the process with kill -STOP does and why the telnet was successful when the httpd process is no longer running ?


httpd processes should be stopped using the following command

systemctl stop httpd.service

why the telnet was successful when the httpd process is no longer running ?

systemd may have restarted the processes when you stopped them manually.

  • This does not address what the question asks at all. For starters, the question is not about the TERM or KILL signals.
    – JdeBP
    Apr 2 '19 at 7:56

Sig stop will pause a process, you can un-pause with sig cont (continue). You do not, normally, want to be doing this to a service. (The shell stop to a process when you press ctrl-z.)

I don't know why it was responding, maybe because the web-server had started child worker processes.

  • Thank you for the response, I double checked there are no active running child processes for apache. If a process is paused, should that not sort of pause the service's ability too. I am trying to figure out why the server is able to respond to requests on port 80 when the apache's process is not actively running. AFAIK the service is dependent on the underlying process, if the process is not working shouldn't the service be unresponsive too ? I may be misunderstanding the process to service and vice versa workflow here,i apologies if that's the case.
    – Atul
    Apr 2 '19 at 12:26
  • 1
    Yep, a service is just at least one process doing something. So if service is only one process, and it is stopped than, service should be stopped. Apr 3 '19 at 6:37

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