hostname of your CentOS 7 Linux is defined by the file
/etc/hostname thus setting a new hostname for your system is just a matter of editing this file and replace a current hostname definition line with new one. However, doing so will not update your system;s hostname immediately thus a preferred way of changing a hostname on CentOS 7 Linux is to use
nmtui and more specifically its child
nmtui-hostname tool will make the process of changing your hostname rather simple as executing a single command. The following linux command will change the hostname to
# nmtui-hostname linuxconfig.org
Hit the “OK” button on the pop-up dialog and you are done.
# hostname linuxconfig.org