Linux Signal Processing

A signal is a software interruption. When a program receives a signal, it calls the corresponding processing function (if registered ).

Void (* signal (int signum, void (* handler) (int); -- set the signal processing method void foo (int arg), a prototype of the signal processing function ); the signal defined by the system is/* Signals. */# define SIGHUP1/* Hangup (POSIX ). */# define SIGINT2/* Interrupt (ANSI ). */# define SIGQUIT3/* Quit (POSIX ). */# define SIGILL4/* Illegal instruction (ANSI ). */# define SIGTRAP5/* Trace trap (POSIX ). */# define SIGABRT6/* Abort (ANSI ). */# define SIGIOT6/* IOT trap (4.2 BSD ). */# define SIGBUS7/* BUS error (4.2 BSD ). */# define SIGFPE8/* Floating-point exception (ANSI ). */# define SIGKILL9/* Kill, unblockable (POSIX ). */# define SIGUSR110/* User-defined signal 1 (POSIX ). */# define SIGSEGV11/* Segmentation violation (ANSI ). */# define SIGUSR212/* User-defined signal 2 (POSIX ). */# define SIGPIPE13/* Broken pipe (POSIX ). */# define SIGALRM14/* Alarm clock (POSIX ). */# define SIGTERM15/* Termination (ANSI ). */# define SIGSTKFLT16/* Stack fault. */# define SIGCLDSIGCHLD/* Same as SIGCHLD (System V ). */# define SIGCHLD17/* Child status has changed (POSIX ). */# define SIGCONT18/* Continue (POSIX ). */# define SIGSTOP19/* Stop, unblockable (POSIX ). */# define SIGTSTP20/* Keyboard stop (POSIX ). */# define SIGTTIN21/* Background read from tty (POSIX ). */# define SIGTTOU22/* Background write to tty (POSIX ). */# define SIGURG23/* Urgent condition on socket (4.2 BSD ). */# define SIGXCPU24/* CPU limit exceeded (4.2 BSD ). */# define SIGXFSZ25/* File size limit exceeded (4.2 BSD ). */# define SIGVTALRM26/* Virtual alarm clock (4.2 BSD ). */# define SIGPROF27/* Profiling alarm clock (4.2 BSD ). */# define SIGWINCH28/* Window size change (4.3 BSD, Sun ). */# define SIGPOLLSIGIO/* Pollable event occurred (System V ). */# define SIGIO29/* I/O now possible (4.2 BSD ). */# define SIGPWR30/* Power failure restart (System V ). */# define SIGSYS31/* Bad system call. */# define SIGUNUSED31 # define_NSIG65/* Biggest signal number + 1 (including real-time signals ). */# define SIGRTMIN (_ libc_current_sigrtmin () # define SIGRTMAX (_ libc_current_sigrtmax ()) Send signal to process (on Terminal)Kill-s signal pid -- the value of signal is the valid value of kill-s 9 pid in the list above -- this command ends the specified process. The following example shows the signal received by the process.

#include <unistd.h>#include <stdio.h>#include <signal.h>void handler(int arg){    printf("get signal %d\n", arg);    }int main(){    int i;    for (i=0; i<SIGRTMAX; i++)        signal(i, handler);    while(1)    {        pause();    }    return 0;}

 

You can end it with the kill-s 9 pid. Kill is also a callable APIInt kill (pid_t pid, int sig); kill () can be used to send signals specified by the sig parameter to the process specified by the pid parameter. The pid parameter has several situations: pid> 0 sends the signal to the process with the pid ID. Pid = 0 send the signal to all processes in the same process group as the current process pid =-1 send the signal to all processes in the system pid <0 send the signal to the Process Group ID pid absolute value all processes