mjhjmtu

I have a question.
Studying processes management I observed a strange behavior, on a CentOS 7.
I know that killing a parent process, the child processes are killed also. But not in the following case. I ran the command dd, just for example:

[root@server2 ~]# dd if=/dev/zero of=/dev/null &
[1] 1756

[root@server2 ~]# ps fax | grep -B2 dd
1737 pts/2 S 0:00 _ su -
1741 pts/2 S 0:00 _ -bash
1756 pts/2 R 1:18 _ dd if=/dev/zero of=/dev/null

After that I tried to kill (with SIGKILL signal) the parent process, that is the bash, but this action doesn't kill the dd process:

[root@server2 ~]# kill -9 1741
Killed
[user@server2 ~]#

The shell terminates but as you can see in the top command output, the dd process is still working:

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 
1756 root 20 0 107948 612 512 R 99.9 0.1 10:06.98 dd 

Do you have any idea about it please? Thanks

By default killing a parent process does not kill the children processes.

I suggest you look for other questions about how to kill both the parent and child using the process group (a negative PID).

A good answer about how to do this in detail can be found at Process descendants