signal hangler problem

mohsin-mm · 02-16-2006, 02:14 PM

hello guyz plz help me in sorting our these problems of this script plz chek this is correct i m getting errors while compiling .. these are the errors

==========================================
sig2.c: In function `main':
sig2.c:10: `SIGINT' undeclared (first use in this function)
sig2.c:10: (Each undeclared identifier is reported only once
sig2.c:10: for each function it appears in.)
sig2.c:11: `SIGQUIT' undeclared (first use in this function)
sig2.c: In function `sigproc':
sig2.c:16: `SIGINT' undeclared (first use in this function)
==============================================
file
=================================================
[mohsin@localhost signals]$ vi sig2.c

#include <stdio.h>

void sigproc(void);

void quitproc(void);

main()
{
signal(SIGINT, sigproc);
signal(SIGQUIT, quitproc);
printf("ctrl-c disabled use ctrl-\\ to quit \n");
for(;

; /* infinite loop */}

void sigproc()
{ signal(SIGINT, sigproc); /* */
/* NOTE some versions of UNIX will reset signal to default
after each call. So for portability reset signal each time */

printf("you have pressed ctrl-c \n");
}
==================================
also i m searhing any examples for practicing basic signals in linux if any one of you find plz share ... in this forum
thnx alot

mohsin-mm · 02-16-2006, 02:15 PM

the simely in the for loop is due to textshortcut i hope you all know

plz reply thnx

bigearsbilly · 02-16-2006, 04:28 PM

#include <signal.h> ??

mohsin-mm · 02-17-2006, 10:31 AM

thnx for replying dear now i get these errors after including signal.h
===========
sig2.c:11: warning: passing arg 2 of `signal' from incompatible pointer type
sig2.c:12: warning: passing arg 2 of `signal' from incompatible pointer type
sig2.c: In function `sigproc':
sig2.c:17: warning: passing arg 2 of `signal' from incompatible pointer type

mohsin-mm · 02-17-2006, 10:32 AM

if any other link to basic signal handling link plz tell me thnx

graemef · 02-17-2006, 10:58 AM

The following C code should work.

Code:

#include <stdio.h>     /* standard I/O functions                         */
#include <unistd.h>    /* standard unix functions, like getpid()         */
#include <signal.h>    /* signal name macros, and the signal() prototype */

/* first, here is the signal handler */
void catch_int(int sig_num)
{
    /* re-set the signal handler again to catch_int, for next time */
    signal(SIGINT, catch_int);
    printf("Don't do that\n");
    fflush(stdout);
}

int main(int argc, char* argv[])
{
    /* set the INT (Ctrl-C) signal handler to 'catch_int' */
    signal(SIGINT, catch_int);
    /* now, lets get into an infinite loop of doing nothing. */
    for ( ;; )
        pause();
}

Taken from Introduction to Unix Signals Programming

mohsin-mm · 02-18-2006, 01:11 AM

thnx dear ... but could you tell me that what this function do coz i m not on root acount so might it do anything wrong ... i dotn think so

mohsin-mm · 02-18-2006, 01:13 AM

thnx finally your code helped me

good work , plz tell me the code
signal(SIGINT, catch_int);
howz it handle the ctrl + c signal ... or its default handler

signal() functions
kz what to do if i use this code to handle do same but for "ct+z"

also sig_ign is used to ignore a signal i think does that work

thnx

graemef · 02-18-2006, 05:55 PM

Ctrl + C is SIGINT the interupt signal
Ctrl + Z is SIGTSTP the suspend signal