cb969dfd41
- 添加了一个新的演示课程示例代码文件 `/process_basic/daemon/mydaemon.c` - 实现了一个单实例守护进程的示例代码 - 添加了一个新的演示课程示例代码文件 `/process_basic/system.c` - 实现了一个使用系统调用 `system()` 执行命令的示例代码 - 添加了一个新的演示课程示例代码文件 `/process_basic/system1.c` - 实现了一个使用进程相关系统调用 `fork()`、`execl()` 和 `wait()` 的示例代码
83 lines
1.4 KiB
C
83 lines
1.4 KiB
C
#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/syslog.h>
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#include <syslog.h>
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#include <time.h>
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#include <unistd.h>
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#define FNAME "/tmp/out"
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static int deamonize(void)
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{
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pid_t pid;
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int fd;
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pid = fork();
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if (pid < 0)
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return -1;
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if (pid > 0) // parent process
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exit(0);
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fd = open("/dev/null", O_RDWR);
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if (fd < 0)
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return -1;
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dup2(fd, 0);
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dup2(fd, 1);
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dup2(fd, 2);
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if (fd > 2)
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close(fd);
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setsid();
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chdir("/"); // 防止一直占用某设备
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// umask(0);
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return 0;
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}
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int main(int argc, char **argv)
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{
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FILE *fp;
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int i;
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openlog("mydaemon", LOG_PID, LOG_DAEMON);
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if (deamonize())
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{
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syslog(LOG_ERR, "daemonize() failed!");
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exit(1);
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}
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else
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{
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syslog(LOG_INFO, "daemonize() success!");
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}
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fp = fopen(FNAME, "w");
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if (fp == NULL)
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{
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syslog(LOG_ERR, "fopen() failed!: %s", strerror(errno));
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exit(1);
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}
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syslog(LOG_INFO, "%s was opened successfully!", FNAME);
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for (i = 0;; i++)
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{
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fprintf(fp, "%d\n", i);
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fflush(fp); //! 刷新缓冲区
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syslog(LOG_DEBUG, "%d is printed", i);
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sleep(1);
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}
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// 目前守护进程只能异常终止，下面其实无法执行到
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fclose(fp);
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closelog();
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exit(0);
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} |