沈阳网站制作的公司网页在线代理翻墙

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
int main(int argc, char const *argv[])
{// 1,忽略挂断信号SIGHUP，防止被终端误杀//SIG_IGN:忽略指定的信号signal(SIGHUP, SIG_IGN);pid_t pid = fork();//父进程结束if (pid > 0)_exit(-1);//子进程设置会话setsid();//改变工作目录（非必须）chdir("/");//设置权限掩码umask(0002);//关闭文件描述符0 1 2close(0);close(1);close(2);//守护进程的核心任务while (1){//核心任务}return 0;
}

多进程

#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <stdlib.h>
int main(int argc, char const *argv[])
{//错误演示:创建两个子进程//实际创建了3个,主线程2个,子线程一个// for (int i = 0; i < 2; i++)// {// int pid = fork();// }//正确演示:创建两个子进程//主线程创建2个,子线程不创建for (int i = 0; i < 2; i++){int pid = fork();if(pid == 0){break;}}return 0;
}

退出

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<sys/wait.h>
#include<stdlib.h>//exit
int main(int argc, char *argv[])
{//创建3个子进程int i=0;for(i=0;i<3;i++){pid_t pid = fork();if(pid == 0)//子进程break;}if(i==0)//子进程1{//任务1的代码printf("子进程1：%u\n", getpid());sleep(5);_exit(-1);}else if(i==1)//子进程2{//任务2的代码printf("子进程2：%u\n", getpid());sleep(3);_exit(-1);}else if(i==2)//子进程3{//任务3的代码printf("子进程3：%u\n", getpid());sleep(4);_exit(-1);}else if(i == 3)//父进程{//回收子进程的资源while(1){//-1:等待任一子进程//WNOHANG:不阻塞pid_t ret = waitpid(-1, NULL, WNOHANG);if(ret > 0){printf("子进程:%u已经退出\n", ret);}else if(ret == 0){continue;//还有子进程在运行 需要继续等待}else if(ret < 0){break;//所有子进程都已经结束}}}return 0;
}

进程补充

终端

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<sys/wait.h>
#include<stdlib.h>//exit
int main(int argc, char *argv[])
{pid_t pid = fork();if(pid == 0)//子进程{sleep(3);int num = 0;scanf("%d", &num);printf("子进程%u中的num=%d,所属终端名:%s\n", getpid(), num,ttyname(0));}else if(pid > 0)//父进程{int num = 0;scanf("%d", &num);printf("父进程%u中的num=%d,所属终端名:%s\n", getpid(), num,ttyname(0));}return 0;
}

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<sys/wait.h>
#include<stdlib.h>//exit
int main(int argc, char *argv[])
{pid_t pid = fork();setpgid(pid,pid);if(pid == 0)//子进程{printf("子进程%d,所属组id:%d\n", getpid(), getpgrp());}else if(pid > 0)//父进程{printf("父进程%d,所属组id:%d\n", getpid(), getpgrp());}while(1);return 0;
}

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<sys/wait.h>
#include<stdlib.h>//exit
int main(int argc, char *argv[])
{pid_t pid = fork();if(pid == 0)//子进程{printf("子进程1id:%d\t,所属组id:%d\t,会话id:%d\n",getpid(),getpgrp(),getsid(getpid()));sleep(2);setsid();printf("子进程2id:%d\t,所属组id:%d\t,会话id:%d\n",getpid(),getpgrp(),getsid(getpid()));while(1);}else if(pid > 0)//父进程{printf("主进程id:%d\t,所属组id:%d\t,会话id:%d\n",getpid(),getpgrp(),getsid(getpid()));while(1);}return 0;
}

#include<stdio.h>
#include<sys/types.h>
#include<unistd.h>
#include<sys/wait.h>
#include<stdlib.h>
int main(int argc, char *argv[])
{int num = 10;// pid_t pid = fork();pid_t pid = vfork();if(pid == 0)//子进程{num=100;printf("子进程num=%d\n",num);// sleep(3);_exit(-1);}else if(pid > 0)//父进程{// wait(NULL);printf("主进程num=%d\n",num);}return 0;
}

#include <stdio.h>
#include <unistd.h>
int main(int argc, char const *argv[])
{//which 命令，查看命令存储路径/*execl("命令存储路径","命令名","参数1","参数2",...,NULL);*/// execl("/usr/games/sl","sl",NULL);// execl("/bin/ls","ls","-a","-l","-h",NULL);// execl("/bin/ls","ls","-alh",NULL);/*execlp:从path环境变量下查找指定名,如果没有无法运行execlp("命令名","命令名","参数1","参数2",...,NULL)env命令查看环境变量*/// execlp("ls","ls","-alh",NULL);// char *tem[] = {"/ls","-alh",NULL};// execv("/bin/ls",tem);char *tem[] = {"/ls","-alh",NULL};//execvp("ls",tem);execvpe("ls",tem);return 0;
}

#include <stdio.h>
#include <unistd.h>
int main(int argc, char const *argv[])
{printf("exec执行前\n");//exec后的程序将不在执行execl("/bin/ls","ls","-alh",NULL);printf("exec执行后\n");return 0;
}

#45_test.c文件
#include <stdio.h>
#include <unistd.h>q
int main(int argc, char const *argv[])
{for (int i = 0; i < 3; i++){printf("test:%d\n",i);sleep(1);}return 0;}
#使用gcc 45_test.c -o 45_test,将源文件编译为可执行文件
#45_code.c文件
#include <stdio.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, char const *argv[])
{int pid = vfork();if (pid < 0){printf("创建进程失败");return 0;}else if(pid == 0){//子进程中代码// for(int i = 0; i < 3; i++)// {// sleep(1);// printf("子进程:%d\n",i);// }execl("./45_test","45_test",NULL);_exit(-1);}else if(pid > 0){// 父进程中代码for(int i = 0; i < 6; i++){printf("code:%d\n",i);sleep(1);}return 0;
}

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
int main(int argc, char const *argv[])
{printf("system前\n");system("ls -alh");printf("system后\n");return 0;
}