End a background process by executing it again in another console, how can it be done?

Question

I have a program in C that is required to run in the background. It mimics the smartfolder that you can find on OSX.

I have been asked to kill end it by writing it's execution command a second time in a console.

I thought about saving the pid and using 2nd program to watch for the input but I did not find a way to send the input to a background process.

I've tried using pipe and the background program was reading from it but the inputs were not going to it.

Could someone tell me if it's possible at all and if this is the right way to do it ? Would this work with a daemon process too ?

Answer 1

If you save the PID in a file somewhere, what about just running

kill(pid, SIGTERM);

If you need special cleanup upon handling (like deleting the file in which you store the PID), implement a handler for the TERM signal (see the signal function).

Alternatively, you could use a user signal, SIGUSR1, for instance.

Answer 2

I'm really close to make it work, just my kill function not working but i have the PID of the smartfolder process.

I did the following : if the program is executed with more then 1 arguments, it run the smartfolder which save it's pid to a file.

if it has only one argument, it goes read the txt file named the same as the smartfolder dir to find the PID and send a kill signal with it.

this way when I enter the execution command with only 1 argument it will kill the corresponding process!