#include "apue.h" #include <sys/wait.h> static void sig_int(int); /* our signal-catching function */ int main(int argc, char *argv[]) { printf("uid = %d, gid = %d ", getuid(), getgid()); char buf[MAXLINE]; /* from apue.h */ pid_t pid; int status; // register the signal handler if ( signal(SIGINT, sig_int) == SIG_ERR) err_sys("signal error"); printf("%% "); /* print prompt (printf requires %% to print %) */ while (fgets(buf, MAXLINE, stdin) != NULL) { if (buf[strlen(buf) - 1] == ' ') buf[strlen(buf) - 1] = 0; /* replace newline with null */ if ((pid = fork()) < 0) { err_sys("fork error"); } else if (pid == 0) { /* child */ execlp(buf, buf, (char *)0); err_ret("couldn't execute: %s", buf); exit(127); } /* parent */ if ((pid = waitpid(pid, &status, 0)) < 0) err_sys("waitpid error"); printf("Last pid: %ld ", (long)pid); printf("%% "); } exit(0); } void sig_int(int signo) { printf("sig_int: interrupt %% "); exit(0); // I add this line to exit the program through CTRL+C (SIGINT), CTRL+D is to terminate the program }
代码来自APUE Figure1.10
我编译之后用gdb调试,发现sig_int始终不会被调用
最后终于发现问题是因为编译选项加了-g,在调试状态下signal机制貌似被禁用了