Thread: Signal handling

Hello again!

Unfortunately I encountered problems after finding my function.

What I want to do is to handle the situation where the user tries to end the program by "Ctrl-C" so a temp-file is erased before exiting the program.

I found the function signal(), but I'm not sure how to use it. It seems that you can set it to do some default action when you receive a Ctrl-C for example, but how do I handle it? Can I get it to call a different function for example?

That is if I set a global boolean to true when I have created the tempfile, but before I am done with what I want to do I can erase the tempfile before exiting? (And how would I do that?)

Sorry, the function was sighandler (it has to work in Unix aswell as Linux)

Mats is right. I have found that the best use for signals is when you need a program to behave in a specific way without human intervention, such as forcing a timeout. The setup is somewhat complicated.

if u want 2 call a function on recieving a signal ..

first send the signal using kill()

catch the signal in the desired process using signal() which takes the SIGNAL u want 2 send and d signal handler as arguments.

now define this signalhandler func in ur program and thr call any function u want 2 ..
jus like dat http://www.ecst.csuchico.edu/~beej/g...c/signals.html

Thank you!

The example on that page was great. It does exactly what I wanted in my program so I'll use that.

The reason I want to use a boolean is that the tempfile is used to store information from an "original" which I will remove some information from. The program gets information from a user about systems in use. This is stored in a file called .active. When a user wants to remove a system from that list I copy the original file to .tmp, and then I copy all the systems back to .active except the one to remove. After that it removes the .tmp file.

But the other day I started the program in "remove"-mode, and pressed "Ctrl-C", and when I ran it again it didn't run because the .tmp-file already existed (I don't want to accidentally remove a .tmp-file not created by my program so I check if it exists), so if the user presses Ctrl-C I want to restore the .active-file and remove the .tmp-file before exiting. So that's why I want the boolean (or some other parameter), to know if the .tmp-file has been created before the user has pressed Ctrl-C.

Thanks again for the help. This is a great forum. A lot of talented programmers here :-)