Restore a default behavior of CTRL+C after using SIGINT

Question

I need to write a function which restores default behavior of CTRL+C (terminating process) after pressing CTRL+\ Here's my program:

#include <stdlib.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>

void sig_int(int sig)
{

    printf("U PRESSED CTRL+C\n");
}
void sig_quit(int sig){
            printf("CTRL+C NOW DO ITS KILLING JOB\n");

}
int main(int argc, char** argv) 
{
    signal(SIGINT,sig_int);
    signal(SIGQUIT, sig_quit);

    return 0;
}

Thank you for all the help and descriptions to better understanding :)

Did you look at https://stackoverflow.com/questions/6015498/executing-default-signal-handler especially `SIG_DFL`? — tk421, Jun 08 '18 at 21:05
https://stackoverflow.com/questions/16891019/how-to-avoid-using-printf-in-a-signal-handler — Arkadiusz Drabczyk, Jun 08 '18 at 21:07
And you should not use non-async-signal-safe functions in a signal handler. Per [the C standard](https://port70.net/~nsz/c/c11/n1570.html#note188): "Thus, a signal handler cannot, in general, call standard library functions." — Andrew Henle, Jun 08 '18 at 21:56

score 2 · Accepted Answer · answered Jun 08 '18 at 21:05

2

Taken from the man page on my machine:

To set the default action of the signal to occur as listed above, func should be SIG_DFL.

so signal(SIQUIT, SIG_DFL) if I've understood your question correctly.

answered Jun 08 '18 at 21:05

DrC

7,528
1
22
37

score 2 · Answer 2 · answered Jun 08 '18 at 21:08

2

signal returns the previously configured handler, store it somewhere and then use signal to restore it whenever you want. Also SIG_DFL points to the C run-time's default handler, but that's not always the right one to use.

answered Jun 08 '18 at 21:08

jwdonahue

6,199
2
21
43

2

Wonder what the down-vote is about? – jwdonahue Jun 08 '18 at 21:45

Restore a default behavior of CTRL+C after using SIGINT

2 Answers2