Programming

For a program I am designing, which involves handling the keyboard input Ctrl^c (SIGINT), it is taking ages for the program to actually recognise and perform the corresponding action whenever I run it and hit Ctrl^C at the CL. I have to do at least 3 Ctrl^Cs before the program will actually register and handle SIGINT appropriately.

Currently Im using signal() to map the various types of unix signals (i.e SIGINT, SIGSTSP) to handler functions I have defined in my program. What the handler functions do is call exit(0) (which quits the program) whenever the corresponding signal has been received by the program. As I mentioned before, it is taking several Ctrl^Cs to get the handler functions to be invoked, when it should just be 1 Ctrl^C.

Im unsure what could be causing my problem. Please feel free to make any suggestions.

Please provide sample code so we can understand exeactly what you are doing.

Ive actually solved my own problem, however I will still post up the code (sorry for not doing it earlier) and how I solved it for anyone who is interested

This is basically how I do my signal mapping

Code:

signal(SIGINT, SigHandler);
signal(SIGTSTP,SigHandler);

This is SigHandler()

Code:

void SigHandler()
{
  printf("Process terminating\n");
  exit(0);
}

A design requirement was for me to get the program to check under a network drive if a certain directory existed. To fulfill this requirement, I made my program call the find command from the shell via system(). When I was assembling the shell command, I put /mnt/ in front of the disk I wished to search.

Strangely enough, when I removed /mnt/ from the command string, the search time was reduced and the program ran a lot faster (It wasn't running as fast before). Unfortuntately though Ctrl^C was still not responding in the desired timespan, however Ctrl^Z (SIGTSTP) was. I ended up axing signal(SIGINT, SigHandler); altogether and my problem was solved.

At some point in the future, Id still like to be able to get Ctrl^C to respond a lot faster as using Ctrl^C to terminate a unix-based command or program is more well-known. I think that Ctrl^Z should still be reserved strictly for the suspending process

That is controlled by the intr option of the mount command. From the mount_nfs(1m) man page: