1）输出Linux下的c也不是太难嘛！在linux下编辑，编译，运行

（1）创建test.c文件，然后编辑 test.c文件

（2）编写程序，保存退出

#include<stdio.h>int main(){printf("Linux下的C语言不是太难嘛！");printf("Linux下的C语言不是太难嘛！");return 0;
}

(3)输入 gcc test.c -o test编译文件，并生成test可执行程序文件
(4)输入 ./test 运行 test

2）编写一个简单地c语言程序,根据输入的两个整数求平均值并且在终端输出，通过gcc编译器得到它的汇编程序文件。

#include <stdbool.h>
#include<stdio.h>
int main() {double a,b;double c;printf("请输入两个数值:");scanf("%lf%lf",&a,&b);c=(a+b)/2;printf("%.2lf",c);return 0;
}

3）编写一个c语言程序，打印输出所有的“水仙花数”

#include<stdio.h>
int main(){int a,b,c,d;a = b = c = 0;printf("请输入你要输入的范围：\n");scanf("%d",&d);for(int i = 100; i <d; i++) {a = i % 10;b = (i / 10) % 10;c = i / 100;if((a*a*a + b*b*b + c*c*c) == i) {printf("%d\n" , i);}}
}

4）创建文件init_test.c，并用valgrind检测内存错误，并把代码修改正确

（1）创建文件init_test.c

（2）用valgrind检测内存错误

（3）修改代码

#include<stdio.h>
int main(void){
int x;
scanf("%d",&x);
if(x==0)
printf("x is zero");
else
printf("x is not zero");
return 0;
}

（4）Valgrind验证

5）创建文件test2.c，并用valgrind检测内存错误，并把代码修改正确；

（1）创建文件test2.c

（2）用valgrind检测内存错误

（3）修改代码

#include<stdio.h>
#include<stdlib.h>
void fun(){int *p=(int *)malloc(10*sizeof(int));p[9]=0;free(p);}int main(int argc,char* argv[])
{fun();
return 0;
}  

（4）valgrind验证代码

6）创建文件test3.c，并用valgrind检测内存错误，并把代码修改正确；

（1）创建test3.c文件

（2）用valgrind检测内存错误

（3）修改代码

#include<stdlib.h>
#include<stdio.h>int main(int argc,char *argv[])
{int i=0;int len=4;int* pt=(int *)malloc(len*sizeof(int));int* p=pt;for( i=0;i<len-1;i++){*p++;}*p=5;
printf("the value of p equal:%d",*p);
free(pt);
return 0;}

(4) valgrind测试

7）创建文件test4.c，并用valgrind检测内存错误，并把代码修改正确；

（1）创建test4.c文件

（2）用valgrind检测错误

（3）修改代码

#include<stdio.h>
#include<stdlib.h>
#include<string.h>int main(int argc, char *argv[])
{char x[50];int i;for(i=0;i<50;i++)
{x[i]=i+1;
}strncpy(x+20,x,20);//OKstrncpy(x+21,x,21);strncpy(x,x+20,20); //okstrncpy(x,x+20,20);x[39]='\0';strcpy(x,x+20);x[39]=39;x[40]='\0';strcpy(x,x+21);return 0;}

(4) valgrind测试

8）创建文件test5.c，并用valgrind检测内存错误，并把代码修改正确；

（1）创建test5.c文件

（2）用valgrind进行测试

（3）修改代码

#include<stdlib.h>
#include<stdio.h>int main(int argc,char *argv[]){int i;char* p=(char*)malloc(10);char* pt=p;for(i=1;i<10;i++){p[i]='z';}pt[1]='x';free(pt);return 0;
}

（4）用 valgrind验证代码正确

9）创建文件file1，写入字符串“abcdefghijklmn”； 创建文件file2，写入字符串“ABCDEFGHIJKLMN”;读取file1中的内容，写入file2，使file2中的字符串内容为“ ABCDEFGHIJKLMNabcdefghijklmn”

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<fcntl.h>
#include<errno.h>
#include<unistd.h>int main() {int fd1,fd2;fd1=open("file1",O_CREAT|O_RDWR,S_IRWXU);if(fd1< 0) {perror("open :");printf("errno is:%d \n",errno);} elseprintf("open ok\n");fd2=open("file2",O_CREAT|O_RDWR,S_IRWXU);if(fd2< 0) {perror("open:");printf("errno is:%d \n,errno");} elseprintf("open OK \n");int fdw1,fdw2;fdw1=write(fd1,"abcdefghijklmn",15);printf("fdw1:%d\n",fdw1);if(fdw1!=15) {perror("write fd1:");} elseprintf("write OK\n");lseek(fd2,16,SEEK_SET);char buf[20]="ABCDEFGHIJKLMN";fdw2=write(fd2,buf,20);if(fdw2<0)perror ("write fd2:");elseprintf("write OK\n");lseek (fd1,0,SEEK_SET);lseek(fd2,0,SEEK_SET);char re[28];read(fd1,re,14);write(fd2,re,14);close(fd1);close(fd2);return 0;
}

10）创建新文件，该文件具有用户读写权限。采用dup/dup2/fcntl复制一个新的文件描述符，通过新文件描述符向文件写入“class_name”字符串；通过原有的文件描述符读取文件中的内容，并且打印显示；

#include<stdio.h>
#include<string.h>
#include<fcntl.h>
#include<stdlib.h>
#include<unistd.h>
#include<sys/types.h>
#include<sys/stat.h>int main() {int fd1,fd2;fd1=open("file",O_RDWR|O_CREAT,0644);fd2=dup(fd1);char str[30];char name[30]="class_name";lseek(fd2,0,SEEK_SET);write(fd2,name,30);lseek(fd1,0,SEEK_SET);read(fd1,str,30);printf("%s",str);close(fd1);return 0;
}

11）输入文件名称，能够判断文件类型，判断实际用户对该文件具有哪些存取权限；要求打印出文件类型信息，inode节点编号，链接数目，用户id，组id，文件大小信息；修改文件的权限为当前用户读写，组内用户读写，组外用户无权限。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>
int main(int argc,char *argv[]) {if(argc < 2) {printf("Please input the filename!\n");return 0;}struct stat statbuf;int i;for(i = 1; i < argc; i++) {if(lstat(argv[i],&statbuf) < 0)perror("lstat");char *buf;if(S_ISREG(statbuf.st_mode))buf = "Regular file!";else if(S_ISDIR(statbuf.st_mode))buf = "Directory file!";else if(S_ISCHR(statbuf.st_mode))buf = "Char file!";elsebuf = "Other file!";printf("The %s is:%s\n",argv[i],buf);printf("The %s mode is:%d\n",argv[i],statbuf.st_mode);printf("The %s inode is:%d\n",argv[i],statbuf.st_ino);printf("The %s uid is:%d\n",argv[i],statbuf.st_uid);printf("The %s gid is:%d\n",argv[i],statbuf.st_gid);printf("The %s size is:%d\n",argv[i],statbuf.st_size);printf("The %s link num is:%d\n",argv[i],statbuf.st_nlink);}for(i = 1; i < argc; i++) {if(access(argv[i],R_OK))printf("The user can read the %s\n",argv[1]);else if(access(argv[i],W_OK))printf("The user can write the %s\n",argv[1]);else if(access(argv[i],X_OK))printf("The user can read and write the %s\n",argv[1]);}for(i = 1; i < argc; i++) {if(chmod(argv[i],0660) < 0)perror("chmod");elseprintf("The file.mode chmod successful!\n");}return 0;
}

12）新建文件，设置文件权限屏蔽字为0；建立该文件的硬链接文件，打印硬链接文件的inode节点号和文件大小；建立该文件的软链接文件，打印软链接文件的inode节点号和文件大小；打印软链接文件中的内容；打印源文件的inode节点号，文件大小和链接数目；调用unlink对源文件进行操作，打印源文件链接数目；

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
int main() {umask(0);struct stat statbuf;int fd = open("file",O_CREAT|O_RDWR);if(fd < 0)perror("open");char *str = "hello world";if(write(fd,str,strlen(str)) < 0)perror("write");link("./file","./hard_link");if(lstat("hard_link",&statbuf) < 0)perror("lstat");printf("The hard_link's inode is: %d\n",statbuf.st_ino);printf("The hard_link's size is: %d\n",statbuf.st_size);symlink("file","sort_link");if(lstat("sort_link",&statbuf) < 0)perror("lstat");printf("The sort_link's inode is: %d\n",statbuf.st_ino);printf("The sort_link's size is: %d\n",statbuf.st_size);char buf[4];readlink("sort_link",buf,4);printf("The sort_link is: %s\n",buf);if(lstat("file",&statbuf) < 0)perror("lstat");printf("The file's inode is: %d\n",statbuf.st_ino);printf("The file's size is: %d\n",statbuf.st_size);printf("The frist linknum is: %d\n",statbuf.st_nlink);unlink("file");if(lstat("file",&statbuf) < 0)perror("lstat");printf("The second linknum is: %d\n",statbuf.st_nlink);close(fd);return 0;
}

13）新建/home/user目录；把当前工作路径移至/home/user目录；打印当前工作路径；

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/types.h>
int main() {char str[128];if(getcwd(str,128) < 0)perror("getwcd");elseprintf("The workdir is:%s\n",str);if(mkdir("/home/user",0666) < 0)perror("mkdir");elseprintf("The dir create successfully!\n");if(chdir("/home/user") < 0)perror("chdir");else {getcwd(str,128);printf("The workdir is:%s\n",str);}rmdir("/home/user");return 0;
}

14）编写程序完成以下功能：递归遍历/home目录，打印出所有文件和子目录名称及节点号。判断文件类型，如果是子目录，继续进行递归遍历，直到遍历完所有子目录为止。

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>void show(char *path) {DIR *dir;char str[128];struct dirent *dirp;struct stat statbuf;dir = opendir(path);if(dir) {while((dirp = readdir(dir)) != NULL) {sprintf(str,"%s/%s",path,dirp->d_name);if(lstat(str,&statbuf) < 0)perror("lstat");if(dirp->d_name[0] == '.')continue;if(S_ISDIR(statbuf.st_mode)) {show(str);printf("The dirent's name is: %s\n",dirp->d_name);printf("The dirent's inode is: %d\n",dirp->d_ino);} else {printf("The file's name is: %s\n",dirp->d_name);printf("The file's inode is: %d\n",dirp->d_ino);}}} elseperror("opendir");closedir(dir);
}int main() {show("/home");return 0;
}

15）打印当前所有环境变量的值；添加新的环境变量NEWENV=first；修改环境变量NEWENV的值为second；打印环境变量NEWENV的值。

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
extern char **environ;int main() {char **env = environ;while(*env) {printf("The env is: %s\n",*env);env++;}putenv("NEWENV=first");char *str;str = getenv("NEWENV");printf("The NEWENV is: %s\n",str);if(setenv("NEWENV","second",1) < 0)perror("setenv");str = getenv("NEWENV");printf("The NEWENV is: %s\n",str);return 0;
}

16）打印字符串“hello world！”，在打印字符串“hello world！”前调用三次fork，分析打印结果。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>int main()
{fork();fork();fork(); printf("hello world!!!\n");return 0;
}

17）在子进程中打开文件file1，写入自己的“班级_姓名_学号”，父进程读取file1中的内容，并且打印显示。在父进程中获取已经结束的子进程的状态信息，打印该信息，并且打印结束的子进程的进程号。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>
int main() {int fd,pid;fd = open("file",O_CREAT|O_RDWR,S_IRWXU);if(fd< 0)perror("open");pid = fork();if(pid  == 0) {printf("This is the child!\n");char str[128] = "class__name_× × × × ×";if(write(fd,str,128) < 0)perror("write");exit(5);} else {printf("This is the father!\n");char buf[128];int n,status;if(read(fd,buf,128) < 0)perror("read");printf("The buf is: %s\n",buf);if(wait(&status) < 0)perror("perror");if(WIFEXITED(status))n = WEXITSTATUS(status);elseprintf("wait error!\n");printf("The child's pid is: %d\n",pid);printf("The child exit status is: %d\n",n);}return 0;
}

18）在父进程中定义变量n，在子进程中对变量n进行++操作；并且打印变量n的值，打印子进程pid；在父进程中打印变量n的值，并且打印父进程pid。要求分别用fork和vfork创建子进程。

创建fork.c文件,编写代码

#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
int main() {int n = 1;if(fork() == 0) {printf("This is child,the pid is%d\n",getpid());printf("The n is: %d\n",++n);} else {printf("This is father,the pid is%d\n",getpid());printf("The n is: %d\n",n);}return 0;
}

创建vfork.c文件

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int main() {int n = 1;pid_t pid;pid = vfork();if(pid < 0)perror("vfork");else if(pid == 0) {printf("This is child,the child's pid is: %d\n",getpid());printf("The n is: %d\n",++n);exit(0);} else {printf("This is father,the father's pid is: %d\n",getpid());printf("The n is: %d\n",n);}return 0;
}

19）创建子进程一，在子进程中递归打印/home目录中的内容（用exec系列函数调用第二次实验中的代码完成此功能）；子进程结束的时候完成以下功能：打印字符串“Child process exited！”。打印子进程标识符，打印父进程标识符。创建子进程二， 打印子进程运行环境中环境变量“USER”的值，通过exec系列中的某个函数设置子进程”USER”环境变量值为“zhangsan”，并且让该子进程完成以下命令：“ls –li /home”.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>void fun() {printf("\n");printf("Child process exited!!!\n");printf("The child's pid is: %d\n",getpid());printf("The father's pid is %d\n",getppid());printf("\n");
}int main() {pid_t pid;pid = vfork();if(pid <0)perror("vfork");else if(pid == 0) {printf("This is the child1 !!!\n");atexit(fun);if((execl("/home/wang/test/file/test6/test","test",NULL)) < 0) {perror("execl");exit(0);}} else {printf("This is the father !!!\n");if(vfork() == 0) {printf("This is the child2 !!!\n");printf("The child2's father's pid is: %d\n",getppid());char * env[] = {"USER=zhangsan",NULL};char *p;p = getenv("USER");if(p) {printf("The user is: %s\n",p);}system("ls -li /home");if((execle("/bin/env","env",NULL,env)) < 0)perror("execle");exit(1);}}return 0;
}

20）编程实现以下功能：主线程实现以下功能： ① 定义全局变量key；② 创建两个线程；③ 如果线程正常结束，得到线程的结束状态值，并打印；线程一完成以下操作：① 设置全局变量key的值为字符串“hello world”；② 打印3次字符串“当前线程ID：key值”；③ 接收到线程二发送的取消请求信号后退出；④ 结束的时候打印字符串“thread1 ，exited！：key值”；线程二完成以下操作：① 设置key值为6；② 给线程一发送取消请求信号；

创建 Thread_test.c文件，编写程序

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <pthread.h>
pthread_key_t key;void cleanup(void *arg) {printf("%s\n",(char *)arg);
}void *child_thread1(void *arg) {char *str = "Hello World";printf("The child_thread1 run!\n");printf("The thread id is: %d\n",syscall(SYS_gettid));if(pthread_setspecific(key,str) < 0)perror("pthread_setspecific");char *get_key = (char *)pthread_getspecific(key);printf("The thread1's key is: %s\n",get_key);pthread_cleanup_push(cleanup,"Thread1,exited!");pthread_cleanup_pop(1);
}void *child_thread2(void *arg) {int num = 6;printf("The child_thread2 run!\n");if(pthread_cancel((pthread_t)arg) < 0)perror("pthread_cancle");if(pthread_setspecific(key,(void *)num) < 0)perror("pthread_setspecific");int *get_key = (int *)pthread_getspecific(key);printf("The thread2's key is: %d\n",get_key);pthread_cleanup_push(cleanup,"Thread2,exited!");pthread_cleanup_pop(1);
}void *thread(void *arg) {pthread_t tid1,tid2;void *tret1,*tret2;printf("This is the main pthread!\n");if(pthread_key_create(&key,NULL) < 0)perror("phtread_key_create");if(pthread_create(&tid1,NULL,(void *)child_thread1,NULL) < 0)perror("pthread_create");pthread_join(tid1,&tret1);printf("The pthread1 exited is: %d\n",(long)tret1);if(pthread_create(&tid2,NULL,(void *)child_thread2,&tid1) < 0)perror("pthread_create");pthread_join(tid2,&tret2);printf("The pthread2 exited is: %d\n",(long)tret2);
}int main() {pthread_t id;if(pthread_create(&id,NULL,(void *)thread,NULL) < 0)perror("pthread_create");sleep(1);return 0;
}

21）用多线程实现生产者消费者，至少有两个消费者和两个生产者

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/sem.h>
#include <pthread.h>
#include <unistd.h>
#include <signal.h>#define BUFFER_SIZE	10
#define SEM_KEY		1234struct circle_buf {int r;int w;int buf[BUFFER_SIZE];
};int semid;
struct sembuf semaphore;
struct circle_buf cbuf;void writecbuf(struct circle_buf *cbuf, int val) {cbuf->buf[cbuf->w] = val;cbuf->w = (cbuf->w + 1) % BUFFER_SIZE;
}int readcbuf(struct circle_buf *pcbuf) {int value = pcbuf->buf[pcbuf->r];pcbuf->buf[pcbuf->r] = -1;pcbuf->r = (pcbuf->r + 1) % BUFFER_SIZE;return value;
}void outcbuf(struct circle_buf *pcbuf) {int i = 0;printf("缓冲区各单元的值：");for (i = 0; i < BUFFER_SIZE; ++i) {printf("%d%c", pcbuf->buf[i],(i == BUFFER_SIZE - 1) ? '\n' : ' ');}
}int initsembuf(void) {int sem = 0;if ((semid = semget(SEM_KEY, 3, IPC_CREAT | 0666)) >= 0) {sem = 1;semctl(semid, 0, SETVAL, sem);sem = BUFFER_SIZE;semctl(semid, 1, SETVAL, sem);sem = 0;semctl(semid, 2, SETVAL, sem);return 1;} else {return 0;}
}void pmutex(void) {semaphore.sem_num = 0;semaphore.sem_op = -1;semaphore.sem_flg = SEM_UNDO;semop(semid, &semaphore, 1);
}void vmutex(void) {semaphore.sem_num = 0;semaphore.sem_op = 1;semaphore.sem_flg = SEM_UNDO;semop(semid, &semaphore, 1);
}void pempty(void) {semaphore.sem_num = 1;semaphore.sem_op = -1;semaphore.sem_flg = SEM_UNDO;semop(semid, &semaphore, 1);
}void vempty(void) {semaphore.sem_num = 1;semaphore.sem_op = 1;semaphore.sem_flg = SEM_UNDO;semop(semid, &semaphore, 1);
}void pfull(void) {semaphore.sem_num = 2;semaphore.sem_op = -1;semaphore.sem_flg = SEM_UNDO;semop(semid, &semaphore, 1);
}void vfull(void) {semaphore.sem_num = 2;semaphore.sem_op = 1;semaphore.sem_flg = SEM_UNDO;semop(semid, &semaphore, 1);
}void sigend(int sig) {semctl(semid, 3, IPC_RMID);exit(0);
}void *productthread(void *arg) {int val = *(int *)arg;while (1) {pempty();pmutex();writecbuf(&cbuf, val);printf("生产者%d写入缓冲区的值=%d.\n", val, val);outcbuf(&cbuf);vmutex();vfull();}return NULL;
}void *consumerthread(void *arg) {int cid = *(int *)arg;int val = 0;while (1) {pfull();pmutex();val = readcbuf(&cbuf);printf("消费者%d取走的产品的值=%d.\n", cid, val);outcbuf(&cbuf);vmutex();vempty();}return NULL;
}int main(int argc, char *argv[]) {while (!initsembuf()) {;}signal(SIGINT, sigend);signal(SIGTERM, sigend);int i = 0;int ret = 0;int consnum = 0;int prodnum = 0;cbuf.r = 0;cbuf.w = 0;memset(cbuf.buf, 0, BUFFER_SIZE);printf("请输入生产者进程的数目：");scanf("%d", &prodnum);int *prosarg = (int *)malloc(prodnum * sizeof(int));pthread_t *prosid = (pthread_t *)malloc(prodnum * sizeof(pthread_t));printf("请输入消费者进程的数目：");scanf("%d", &consnum);int *consarg = (int *)malloc(consnum * sizeof(int));pthread_t *consid = (pthread_t *)malloc(consnum * sizeof(pthread_t));for (i = 0; i < prodnum; ++i) {prosarg[i] = i + 1;ret = pthread_create(&prosid[i], NULL, productthread,(void *)&prosarg[i]);printf("消费者prosid[%d] = %lu\n", i + 1, prosid[i]);if (ret != 0) {printf("创建生产者线程失败！");exit(EXIT_FAILURE);}}for (i = 0; i < consnum; ++i) {consarg[i] = i + 1;ret = pthread_create(&consid[i], NULL, consumerthread,(void *)&consarg[i]);printf("生产者consid[%d] = %lu\n", i + 1, consid[i]);if (ret != 0) {printf("创建消费者线程失败！");exit(EXIT_FAILURE);}}sleep(10);return 0;
}

22）利用匿名管道实现父子进程间通信，要求父进程发送字符串“hello child”给子进程；子进程收到父进程发送的数据后，给父进程回复“hello farther”；父子进程通信完毕，父进程依次打印子进程的退出状态以及子进程的pid

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/wait.h>int main() {int fd1[2],fd2[2];pipe(fd1);pipe(fd2);int pid;pid = fork();if(pid < 0)perror("fork");else if(pid == 0) {close(fd1[0]);close(fd2[1]);char str[12];printf("This is the child!\n");if(read(fd2[0],str,12) > 0) {printf("Received the news: %s\n",str);if(write(fd1[1],"hello father",12) < 0)perror("write");} elseperror("read");exit(5);} else {int status;printf("This is the father!\n");close(fd1[1]);close(fd2[0]);char buf[24] = "hello child";if(write(fd2[1],buf,12) < 0)perror("write");else {printf("Send news successful!\n");}wait(&status);if(WIFEXITED(status)) {printf("The child's pid is: %d\n",pid);printf("The child's exited status is: %d\n",WEXITSTATUS(status));}}return 0;
}

23）利用匿名管道实现兄弟进程间通信，要求兄进程发送字符串“This is elder brother ，pid is (兄进程进程号)”给第进程；第进程收到兄进程发送的数据后，给兄进程回复“This is younger brother ，pid is(第进程进程号)”；

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
int main() {int fd1[2],fd2[2];pipe(fd1);pipe(fd2);int pid;pid = fork();if(pid == 0) {printf("This is the elder brother!\n");printf("The elder's father's pid is: %d\n",getppid());close(fd1[1]);close(fd2[0]);char str1[64],str2[64];sprintf(str1,"This is the elder brother,pid is %d",getpid());if(write(fd2[1],str1,64) < 0)perror("write");if(read(fd1[0],str2,64) < 0)perror("read");elseprintf("The news from younger is: %s\n",str2);} else {if(fork() == 0) {printf("This is the younger brother!\n");printf("The younger's father's pid is: %d\n",getppid());close(fd1[0]);close(fd2[1]);char buf1[64],buf2[64];if(read(fd2[0],buf1,64) > 0) {printf("The news form elder is: %s\n",buf1);sprintf(buf2,"This is the younger brother,pid is %d",getpid());if(write(fd1[1],buf2,64) < 0)perror("write");} elseperror("read");}}return 0;
}

24）利用有名管道文件实现进程间通信，要求写进程向有名管道文件写入10次“hello world”；读进程读取有名管道文件中的内容，并依次打印。

#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
int main() {int pid,fd;if(mkfifo("fifotest",0666) < 0)perror("mkfifo");pid = fork();if(pid < 0)perror("fork");else if(pid == 0) {printf("This is the write process!\n");int fd = open("fifotest",0666);for(int i = 0; i < 10; i++) {if(write(fd,"hello world",12) < 0)perror("write");sleep(1);}close(fd);} else {char str[128];printf("This is the read process!\n");int fd1 = open("fifotest",0666);for(int i = 0; i < 10; i++) {if(read(fd1,str,128) < 0)perror("read");elseprintf("%s\n",str);}system("rm -f fifotest");}return 0;
}

25）进程A向进程B发送SIGUSR1信号；进程B收到信号后，打印字符串“receive SIGUSR1”；要求用kill函数和signal函数实现以上功能；

#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<signal.h>
#include<sys/types.h>void fun(int sig)
{if(sig=SIGUSR1){printf("Received SIGUSR1!\n");}
}int main(){printf("This is A process,mypid is:%d\n",getpid());signal(SIGUSR1,fun);pause();return 0;}

第三步：处理结果

因为程序中有pause（）语句，那么程序运行到此就会停下知道有信号发送给此进程。
然后新建一个终端，在终端输入kill -SIGUSR 3701，那么第二个进程就会发送SIGUSR1信号给pid为3701的进程，也就是进程A。之后程序输出字符串，进程结束。

编写killend.c文件

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
void fun(int sig) {if(sig == SIGUSR1)printf("Reseived SIGUSR1!\n");
}
int main() {int pid;if(signal(SIGUSR1,fun) < 0)perror("signal");pid = fork();if(pid < 0)perror("fork");else if(pid == 0) {printf("This is B process!\n");sleep(2);} else {printf("This is A process!\n");if(kill(pid,SIGUSR1) < 0)perror("kill");return 0;}
}

26）调用setitimer函数分别触发SIGALRM信号，SIGVTALRM信号，SIGPROF信号 ；（可以由多进程分别触发每个信号）编写信号安装函数，在该函数内部能判断接受到的是什么信号，并把信号打印出来。

#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <sys/time.h>
#include <unistd.h>
#include <sys/types.h>
void fun(int sig) {if(sig == SIGALRM)printf("Received the SIGALRM!\n");else if(sig == SIGVTALRM)printf("Receive the SIGVTALRM!\n");else if(sig == SIGPROF)printf("Receive the SIGPROf!\n");
}int main() {if(signal(SIGALRM,fun) < 0)perror("signal");if(signal(SIGVTALRM,fun) < 0)perror("signal");if(signal(SIGPROF,fun) < 0)perror("signal");struct itimerval new_value1,new_value2,new_value3;new_value1.it_value.tv_sec = 1;new_value1.it_value.tv_usec = 0;new_value1.it_interval.tv_sec = 2;new_value1.it_interval.tv_usec = 0;setitimer(ITIMER_REAL,&new_value1,NULL);new_value2.it_value.tv_sec = 1;new_value2.it_value.tv_usec = 0;new_value2.it_interval.tv_sec = 2;new_value2.it_interval.tv_usec = 0;setitimer(ITIMER_VIRTUAL,&new_value2,NULL);new_value3.it_value.tv_sec = 1;new_value3.it_value.tv_usec = 0;new_value3.it_interval.tv_sec = 2;new_value3.it_interval.tv_usec = 0;setitimer(ITIMER_PROF,&new_value3,NULL);while(1);return 0;
}

27）进程A向进程B发送SIGUSR1信号；进程B收到信号后，打印字符串“receive SIGUSR1”；要求用sigqueue函数和sigaction函数实现以上功能；

创建send_signal.c 文件

#include <stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <errno.h>int main() {int pid;printf ("请输入你将要发送给信号的进程的进程号：");scanf ("%d",&pid);            //输入接收信号的进程号union sigval mysigval;mysigval.sival_int = 20;if (sigqueue(pid,SIGUSR1,mysigval) == -1)    //向该进程发送信号,并且携带一个整数，这个整数会放在第二个参数中，一起发送给接受信号的进程perror("sigqueue error");elseprintf ("send ok \n");return 0;
}

创建receive_signal.c文件

#include<stdio.h>
#include <signal.h>
#include <sys/types.h>
#include <errno.h>
#include <unistd.h>int main() {int pid;printf ("pid is : %d \n",getpid());void myFun(int sig);struct sigaction act,oldact;act.sa_handler = myFun;        //定义接受信号的处理函数sigemptyset(&act.sa_mask);act.sa_flags = 0;if (sigaction(SIGUSR1,&act,&oldact) == -1)     //信号接收perror("sigaction: \n");pause();return 0;
}void myFun(int sig) {printf("I got a signal:%d\n",sig);printf ("receive SIGUSR1 \n");}

28）进程A向进程B发送信号，该信号的附带信息为一个值为20的整数；进程B完成接收信号的功能，并且打印出信号名称以及随着信号一起发送过来的整形变量值。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <signal.h>
void handler(int sig,siginfo_t* info,void *p) {printf("The num is: %d\n",info->si_value.sival_int);
}int main() {int pid;struct sigaction act;act.sa_sigaction = handler;act.sa_flags = SA_SIGINFO;pid = fork();if(pid < 0)perror("fork");else if(pid == 0) {printf("This is the receive process!\n");if(sigaction(SIGUSR1,&act,NULL) < 0)perror("sigaction");while(1);} else {printf("This is the send process!\n");union sigval mysigval;mysigval.sival_int = 20;sleep(1);if(sigqueue(pid,SIGUSR1,mysigval) < 0)perror("sigqueue");}return 0;
}

29）创建共享内存，写进程通过键盘不断向内存写入“hello world”；如果结束写操作，则通过键盘输入“end”；读进程从共享内存读取数据，并打印。直到读到“end”为止。

创建shmread.c文件

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/shm.h>
#define MAXSIZE 1024struct shm{int write;    //记录读进程是否已经将内容读取char buffer[MAXSIZE];
};int main()
{int shmid;struct shm *share;void *shmptr = NULL;if(shmid = shmget(0X44,MAXSIZE,0666|IPC_CREAT) < 0)perror("shmget");if((shmptr = shmat(shmid,0,0)) == (void *)-1)perror("shmat");printf("This is the read process!!!\n");share = (struct shm *)shmptr;while(1){if(share->write != 0){if(!strncmp(share->buffer,"end",3) == 0){printf("%s",share->buffer);share->write = 0;}elsebreak;}}if(shmdt(shmptr) < 0)perror("shmdt");exit(0);
}

创建shmwrite.c文件

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/shm.h>
#define MAXSIZE 1024
struct shm {int write;        //记录读进程是否已经将内容读取char buffer[MAXSIZE];
};int main() {int shmid;void *shmptr = NULL;char str[MAXSIZE];    //存储输入的内容struct shm *share;if(shmid = shmget(0X44,MAXSIZE,0666|IPC_CREAT) < 0)perror("shmget");if((shmptr = shmat(shmid,0,0)) == (void *)-1)perror("shmat");printf("This is the write process!!!\n");share = (struct shm *)shmptr;while(1) {if(share->write == 1) {sleep(1);printf("Waiting the read process!!!\n");}printf("please input hello world!!!\n");fgets(str,MAXSIZE,stdin);sprintf(share->buffer,"%s",str);share->write = 1;if(strncmp(str,"end",3) == 0)break;sleep(1);}if(shmdt(shmptr) < 0)perror("shmdt");exit(0);return 0;
}

30）进程A向消息队列发送消息“hello，world”，进程B从消息队列读取消息，并打印。进程C向消息队列发送“自己在姓名”，进程D从消息队列中取出姓名字符串，并打印

#include <stdio.h>
#include <stdlib.h>
#include <sys/ipc.h>
#include <unistd.h>
#include <sys/msg.h>
#include <sys/types.h>
struct msg {char msg_str[128];
};int main() {int qid;struct msg mymsg;if(qid = msgget(0x66,0666|IPC_CREAT) < 0)perror("msgget");int pid;pid = fork();if(pid < 0)perror("fork");else if(pid == 0) {printf("This is A process!\n");sprintf(mymsg.msg_str,"hello world");if(msgsnd(qid,&mymsg,128,0) < 0)perror("msgsnd");} else {if(fork() == 0) {printf("This is B process!\n");if(msgrcv(qid,&mymsg,128,0,0) < 0)perror("msgrcv");printf("The msg is: %s\n",mymsg.msg_str);} else if(fork() == 0) {printf("This is the C process!\n");sprintf(mymsg.msg_str,"someonename");if(msgsnd(qid,&mymsg,128,0) < 0)perror("msgsnd");} else {printf("This is D process!\n");if(msgrcv(qid,&mymsg,128,0,0) < 0)perror("msgrcv");printf("The msg is: %s\n",mymsg.msg_str);}}return 0;
}