这个范例中,示范一般标准的daemon写法。
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
void main(void)
{
pid_t pid;
pid = fork();
if (pid>0)
{
printf("daemon on duty!\n");
exit(0);
}
else if (pid<0)
{
printf("Can't fork!\n");
exit(-1);
}
for (;;)
{
printf("I am the daemon!\n");
sleep(3);
/* do something your own here */
}
}
编译:
gcc -o ex2 daemon.c
执行结果:
./ex2
daemon on duty!
I am the daemon!
接下来每三秒钟,都会出现一个"I am the daemon!"的讯息,这表示您的程式已经"长驻"在系统中了。
检验行程:
ps | grep ex2
8753 p0 S 0:00 ./ex2
Signal Operators
int sigemptyset(sigset_t *set);
int sigfillset(sigset_t *set);
int sigaddset(sigset_t *set, int signum);
int sigdelset(sigset_t *set, int signum);
int sigismember(const sigset_t *set, int signum);
Signal Handling Functions
int sigaction(int signum, const struct sigaction *act,struct sigaction *oldact);
int sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
int sigpending(sigset_t *set);
int sigsuspend(const sigset_t *mask);
Structure Signal Action
struct sigaction {
void (*sa_handler)(int);
sigset_t sa_mask;
int sa_flags;
void (*sa_restorer)(void);
}