c18

1. linux中0,1,2代表标准输入，标准输出，标准错误信息输出

cout<<"input: "<<flush;char buf[100] = {};read(0, buf, 5);write(1, buf, 5);

2. 精灵进程：a.fork后父进程结束；b.子进程中setsid();新建回话和组；c. umask(0022);屏蔽权限；d. close(所有文件描述符一般0~255)；

#include <iostream>using namespace std;#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>void make_daemon();void work();int main(){make_daemon();return 0;}void make_daemon(){if (fork() != 0)exit(0);setsid();umask(0077);for (int fd = 0; fd<256; ++fd)close(fd);work();}void work(){char ch = 'A';for(;;){int fd = open("tick.txt", O_WRONLY|O_CREAT|O_APPEND, 0777);if (fd>= 0){write(fd, &ch, 1);close(fd);}ch++;if(ch > 'Z')ch = 'A';sleep(3);}}

3. makefile写法：

a.out:a.o b.o c.og++ a.o b.o c.o #必须要用tab键a.o:a.cc a.hg++ -c a.ccb.o:b.cc a.hg++ -c b.ccc.o:c.ccg++ -c c.cc #$^所有依赖文件# $@目的文件# $<第一个依赖文件# abc = "g++ -c" $(abc)

4. man signal：获取所有信号相关

5. 登记信号处理函数：旧函数名 signal(信号, 函数名fun); void fun(int sig);

#include <iostream>using namespace std;#include <signal.h>void fun(int sig){signal(sig, fun);if(sig == SIGINT)cout<<"ctrl+c"<<endl;else if(sig == SIGUSR1)cout<<"sigusr1"<<endl;elsecout<<"unknown"<<endl;}int main(){cout<<"===1==="<<endl;signal(SIGINT, fun);signal(SIGUSR1, fun);signal(SIGUSR2, fun);cout<<"===2==="<<endl;for(int i = 0; i < 20; ++i){sleep(10);cerr<<'.';}return 0;}

6. #kill -USR1 pid

kill命令发送信号

7. 在某些系统中，signal对某个信号一次有效，不稳定信号；有些系统中会取消正在进行中的阻塞，阻塞函数调用会以出错的方式返回

8. signal(信号, SIG_DEI/SIG_IGE);//default，igore，返回值SIG_ERR表示登记失败

9. kill(pid, 信号);

raise(信号);//给自己发信号

alarm(秒数);//给自己发SIGALRM.

10. pause();暂停直到处理一个信号为止

11. #mkfifo a.f

#ls

a.f|

#ll a.f

prw-r--r-- p为pipe管道的意思

12.int mkfifo("a.fifo", 0600);//管道要同时读写时才能打开

//写#include <iostream>using namespace std;#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>int main(){mkfifo("a.fifo", 0600);//返回int，负失败int fd = open("a.fifo", O_WRONLY);if(fd<0){cerr<<"err"<<endl;return -1;}cout<<"pipe ready!"<<endl;for(;;){cout<<"intput text:";string str;getline(cin, str);write(fd, str.c_str(), str.size());if (str == "bye")break;}close(fd);return 0;}//读#include <iostream>using namespace std;#include <sys/stat.h>#include <fcntl.h>#include <unistd.h>#include <cstring>int main(){mkfifo("a.fifo", 0600);//返回int，负失败int fd = open("a.fifo", O_RDONLY);if(fd<0){cerr<<"err"<<endl;return -1;}cout<<"pipe ready!"<<endl;for(;;){char buf[1000];int n;n = read(fd, buf, 1000);buf[n] = 0;cout<<"info:"<<buf<<endl;if(strcmp(buf, "buf") == 0)break;}close(fd);return 0;}

13. #ipcs 进程间通信状态

#ipcrm -q qid 删除消息队列

14. 消息队列：

//写#include <iostream>using namespace std;#include <sys/ipc.h>#include <sys/msg.h>struct Msg{long no;//第一个必须long型char name[20];int age;};int main(int argc, char** argv){if(argc == 1){cout<<argv[0]<<" key"<<endl;return 0;}int key = atoi(argv[1]);int qid = msgget(key, IPC_CREAT|0600);if(qid<0){cout<<"cannot creat"<<endl;return -1;}cout<<"ok"<<endl;cout<<"key= 0x"<<hex<<key<<endl;cout<<"qid= "<<dex<<qid<<endl;Msg m;cout<<"shuru:"<<end;cin>> m.no>>m.name>>m.age;msgsnd(qid, &m, sizeof(m), 0);return 0;}//读#include <iostream>using namespace std;#include <sys/ipc.h>#include <sys/msg.h>struct Msg{long no;//第一个必须long型char name[20];int age;};int main(int argc, char** argv){if(argc == 1){cout<<argv[0]<<" key"<<endl;return 0;}int key = atoi(argv[1]);int qid = msgget(key, IPC_CREAT|0600);if(qid<0){cout<<"cannot creat"<<endl;return -1;}cout<<"ok"<<endl;cout<<"key= 0x"<<hex<<key<<endl;cout<<"qid= "<<dex<<qid<<endl;Msg m;cout<<"no:"<<end;int no;cin >> no;//输入通道号是用0表示不分通道，都收msgrcv(qid, &m, sizeof(m), no, 0);cout<<m.no<<end;cout<<m.name<<endl;cout<<m.age<<endl;return 0;}//删除队列#include <iostream>using namespace std;#include <sys/ipc.h>#include <sys/msg.h>struct Msg{long no;//第一个必须long型char name[20];int age;};int main(int argc, char** argv){if(argc == 1){cout<<argv[0]<<" key"<<endl;return 0;}int key = atoi(argv[1]);int qid = msgget(key, IPC_CREAT|0600);if(qid<0){cout<<"cannot creat"<<endl;return -1;}cout<<"ok"<<endl;cout<<"key= 0x"<<hex<<key<<endl;cout<<"qid= "<<dex<<qid<<endl;if(msgctl(qid, IPC_RMID, NULL)<0)cout<<"erroer remove"<<endl;elsecout<<"remove ok!"<<endl;return 0;}