One of Perl socket programming

Recently I plan to write a C/S socket monitoring script. An instance is found online. Since we used to have little contact with socket, signals, and other things, we should first understand them before writing.
Below are some basic information about signals: PID> 0 : Send to process ID Is PID Process PID = 0 : Send to the same group, and you have the permission to send The process of sending the message PID <-1 : Send to process group ID Is -PID And Processes with the permission to send to them PID =-1 : All processes that have the permission to send signals to them

(Coming soon)