linux复习资料

1、1、指令格式：指令名称 选择项 参数列表选择项以-开头通配符* ：代表文件名中的任意长度的字符串；？：代表文件名中的任一字符 ：代表文件名中的任一属于字符组中的字符2、3 gcc基本选项类型说明-E预处理后即停止，不进行编译、汇编及连接-S编译后即停止，不进行汇编及连接-c编译或汇编源文件，但不进行连接-o file指定输出文件file程序的编译要经历预处理、编译、汇编以及连接4个阶段。4、其他常用工具：putty、makefile、Emacs编辑器5、Linux系统中“一切皆文件”。Linux操作系统是以文件为基础而设计的，除了常规文件以外，目录、设备、管道等都属于文件。6、文件操作方式：#

2、define O_ACCMODE 0003 /主要访问权限位的低两位用来测试权限用#define O_RDONLY 00#define O_WRONLY 01#defein O_RDWR 02#define O_CREAT 0100#define O_EXCL 0200 /如果存在，返回错误#define O_NOCTTY 0400 /终端控制信息#define O_TRUNC 01000#define O_APPEND 020007、 文件打开与创建： if(fd_open=open("/bin/ls",O_RDONLY) = -1)perror("open&q

3、uot;);exit(EXIT_FAILURE); if(fd_open_create=open("./tmp",O_CREAT|O_EXCL,0644) = -1)perror("open");exit(EXIT_FAILURE);if(fd_create=creat("./tmp2",0644) = -1 )perror("open");exit(EXIT_FAILURE);8、 获取文件属性statint stat ( const char *file_name, struct stat *buf );int

4、 fstat ( int filedes, struct stat *buf );9、 opendir、closedir、readdirDIR *opendir ( const char *name );int closedir (DIR * dirp);struct dirent *readdir ( DIR * dir );10、进程及其状态进程就是程序的一次执行过程。进程至少要有三种基本状态。这三种基本状态是：运行态、就绪态和封锁态（或等待态）。进程转换：11、 条件：由于父子进程执行顺序的不确定性，当子进程先于父进程退出时，子进程会留下一些资源来记录运行的信息，以提供给父进程进行访问。

5、如果父进程没有调用wait或waitpid函数的话，则子进程将会一直保留这些信息，成为僵尸进程。如果父进程调用了wait函数，子进程就不会成为僵尸进程。孤儿进程是指因父亲进程先结束而导致一个子进程被init进程收养的进程。12、 可以通过以下方式结束进程。<1>、调用exit或_exit。<2>、在main函数中执行return。<3>隐含的离开main函数。Return与exit区别：return 退出当前函数主体，exit()函数退出当前进程，因此，在main函数里面return(0)和exit(0)完成一样的功能。return仅仅从子函数中返回，而子进

6、程用exit()退出，调用exit()时要调用一段终止处理程序，然后关闭所有I/O流。13、管道（Pipe）及有名管道（named pipe）：管道可用于具有亲缘关系进程间的通信，有名管道克服了管道没有名字的限制，因此，除具有管道所具有的功能外，它还允许无亲缘关系进程间的通信；管道的实质是一个内核缓冲区，进程以先进先出的方式从缓冲区中存取数据：管道一端的进程顺序地将数据写入缓冲区，另一端的进程则顺序地读出数据。两个局限性：1）支持半双工；2）只有具有亲缘关系的进程之间才能使用这种无名管道；读写特殊性：1.当读一个写端已经关闭的管道时，在所有数据被读取之后，read函数返回值为0，以指示到了文件

7、结束处；2.如果写一个读端关闭的管道，则产生SIGPIPE信号。如果忽略该信号或者捕捉该信号并处理程序返回，则write返回-1，errno设置为EPIPE14、 父子进程通过无名管道通信elseclose(pipe_fd0);printf("please input the string:");scanf("%s",buf_w);if(write(pipe_fd1,buf_w,strlen(buf_w)!=-1)printf("parent process has written:%s to the pipe!n",buf_w);c

8、lose(pipe_fd1);waitpid(result,NULL,0);exit(0);#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/wait.h>#include <unistd.h>#include <string.h>main()pid_t result;int r_num;int pipe_fd2;char buf_r100,buf_w100;memset(buf_r,0,sizeof(buf_r);if(pip

9、e(pipe_fd)<0)perror("pipe");exit(EXIT_FAILURE);result=fork();if(result<0)perror("fork");exit(EXIT_FAILURE);else if(result=0)close(pipe_fd1);if(r_num=read(pipe_fd0,buf_r,100)>0)printf("child process has read %d characters from the pipe,the string is:%sn",r_num,b

10、uf_r);close(pipe_fd0);exit(0);信号是Linux系统中用于进程之间相互通信或操作的一种机制。信号事件的发生有两个来源：1. 硬件来源：用户按某些终端键时将产生信号，如CTRL+C将产生SIGINT（中止信号）；硬件异常产生信号，如除数为0或无效的存储访问等。2. 软件来源：终止进程信号，其他进程调用kill函数，将信号发送个另一个进程或进程组；软件异常产生信号。信号处理信号注销信号注册内核进程用户进程信号产生*生命周期（3）设计一个程序，要求打开文件“pass”，如果没有这个文件，新建此文件；读取系统文件“/etc/passwd”，把文件中的内容都写入“pass”文

11、件。#include <stdio.h>#include <stdlib.h>#include <fcntl.h>#include <string.h>#include <sys/types.h>int main(int agrs,char *args) int fd_src,fd_des,num;char buf10; if(fd_des=open("pass",O_CREAT|O_WRONLY|O_TRUNC,0644)<0) perror("open or create file failed

12、n"); exit(EXIT_FAILURE);if(fd_src=open("/etc/passwd",O_RDONLY,0644)=-1) perror("open passwd file failedn");exit(EXIT_FAILURE); donum =read(fd_src,buf,10);write(fd_des,buf,num);while(num >= 10);close(fd_src); close(fd_des); return 0;（4）设计一个程序，要求新建一个目录，预设权限为d-x-x-x。 #includ

13、e<stdio.h> #include<dirent.h> #include<sys/types.h> #include<sys/stat.h>#include <fcntl.h>#include <stdlib.h>int main(int argc,char *argv)DIR *dir;int fd; if(fd=mkdir("/home/student/dir",0644)=-1) perror("directory created failed!"); exit(EXIT_

14、FAILURE); if(chmod("dir",S_IXUSR|S_IXGRP|S_IXOTH)<0)perror("chomd");exit(EXIT_FAILURE);return 0;. 实现两个进程间使用消息队列进行通信/接受消息#include<unistd.h>#include<stdlib.h>#include<stdio.h>#include<string.h>#include<errno.h>#include<sys/msg.h>#define BUFIZE

15、 1024struct msg_stlong int msg_type;char textBUFIZE;int main()int running=1;int msgid=-1;struct msg_st data;long int msgtype=0;/创建消息队列msgid=msgget(key_t)1234,0666|IPC_CREAT);if(msgid=-1)fprintf(stderr,"msgget failed with error:%dn",errno);exit(EXIT_FAILURE);/从队列中获取消息，直到遇到end消息为止while(runni

16、ng)if(msgrcv(msgid,(void *)&data,BUFIZE,msgtype,0)=-1)fprintf(stderr,"msgget failed with error:%dn",errno);exit(EXIT_FAILURE)；printf("You wrote %sn",data.text);/遇到end结束if(strncmp(data.text,"end",3)=0)running=0;/删除消息队列if(msgctl(msgid,IPC_RMID,0)=-1)fprintf(stderr,&qu

17、ot;msgctl(IPC_RMID)failedn");exit(EXIT_FAILURE);exit(EXIT_SUCCESS);return 0;/发送消息#include<unistd.h>#include<stdlib.h>#include<stdio.h>#include<sys/msg.h>#include<errno.h>#define MAX_TEXT 512#define BUFSIZE 1024struct msg_stlong int msg_type;char textMAX_TEXT;int ma

18、in()nt running=1;struct msg_st data;char bufferBUFSIZE;int msgid=BUFSIZE;/建立消息队列msgid=msgget(key_t)1234,0666|IPC_CREAT);if(msgid=-1)fprintf(stderr,"msgget failed with error:%dn",errno);exit(EXIT_FAILURE);/向消息队列中写消息，直到写入end结束while(running)/写入数据printf("Enter some text:");fgets(buff

19、er,BUFSIZE,stdin);data.msg_type=1;strcpy(data.text,buffer);/消息队列发送消息if(msgsnd(msgid,(void *)&data,MAX_TEXT,0)=-1)fprintf(stderr,"msgsnd failedn");exit(EXIT_FAILURE);/输入end结束if(strncmp(buffer,"end",3)=0)running=0;sleep(1);exit(EXIT_SUCCESS);return 0; 2. 上机调试课件中killrecever和kill

20、sender程序。/killrecever#include <stdio.h>#include <unistd.h>#include <sys/types.h>#include <signal.h>/SIGUSR1信号处理函数void CbSigUsr1(int signo) /输出接收到的信号信息printf("nreceive signal=%d.n",signo);void main()/安装SIGUSR1信号if(signal(SIGUSR1,CbSigUsr1)=SIG_ERR)perror("signal

21、");return;printf("my pid is %dn",getpid(); printf("waiting for SIGUSR1.n");/暂停，等待信号 pause();/killsender#include <stdio.h>#include <signal.h>#include <unistd.h>#include <stdlib.h>void fun_ctrl_c();int main()(void)signal(SIGINT,fun_ctrl_c);printf("

22、Now I'm starting.n");while(1)printf("this is an endless loop unless Ctrl+c are pressd!n");sleep(2);exit(0);void fun_ctrl_c()printf("tCtrl+c were pressed!n");printf("t This is just an example for signal function!n");printf("treset signal SIGINTn");(voi

23、d)signal(SIGINT,SIG_DFL)1. 编程实现由一个父进程产生3个子进程，并且给三个子进程传递不同的参数，收到a的子进程在显示器上输出乘法口诀表；收到b的子进程计算10！；收到c的进程计算1+2+3+19+20的结果。 /计算10！#include<stdio.h> int main()int fac=1,i; for(i=1;i<=10;i+) fac*=i;if(i<10)printf("%d*",i); Else printf("%d=",i); printf("%dn",fac);ret

24、urn 0;/乘法口诀表#include <stdio.h>int main()int i,j,result=0;for(i=1;i<=9;i+)or(j=1;j<=i;j+)result=i*j;printf("%d*%d=%d ",i,j,result);printf("n");return 0;/计算1+2+3+19+20的结果#include<stdio.h> int main()int sum=0,i; for(i=1;i<=20;i+) sum+=i;if(i<20)printf("%

25、d+",i); Else printf("%d=",i); printf("%dn",sum); return 0;/主进程#include<stdio.h>#include<stdlib.h>#include<sys/types.h>#include<unistd.h>int main(int argc,char *argv ) int flag;pid_t pid;int i=1;int sum=0;int fac=1; while(i<4) pid=fork(); if(pid=-1)

26、 perror("fork");exit(EXIT_FAILURE); switch(*argvi) case 'a': if(pid=0)printf("this is 1 child processn");for(int i=1;i<=9;i+)for(int j=1;j<=i;j+)result=i*j;printf("%d*%d=%d ",i,j,result);printf("n");break;case 'b': if(pid=0) sleep(1);prin

27、tf("this is 2 child processn");for(int i=1;i<=10;i+) fac*=i;(i<10)printf("%d*",i);else printf("%d=",i);printf("%dn",fac); break; case 'c': if(pid=0) sleep(2); printf("this is 3 child processn"); for(int i=1;i<=20;i+) sum+=i; if(i<

28、20)printf("%d+",i);else printf("%d=",i); printf("%dn",sum); break;default: exit(EXIT_FAILURE); / if(i!=3) return 0; i+; return 0;2. execve函数的应用，要在程序执行时设定环境变量，路径为tmp，用户为liu，执行命令env时把这些环境变量传递给系统。在这一函数中，参数e表示可传递新进程环境变量，参数v表示传递的参数（含命令）为构造指针数组，文件查找需给出路径。命令env在“/bin”目录下。把环境变量

29、设定为： char *envp=“PATH=/tmp”,”USER=liu”,NULL;参数的构造指针数组为：char *arg=“env”,NULL;因而此函数的调用形式为：execve(“/bin/env”,”env”,envp);请编写程序进行调试。 #include<stdio.h>#include<stdlib.h>#include<unistd.h>int main()char *env="env",NULL; char *envp="PATH=/tmp","USER=liu",NULL

30、; execve("/bin/env",env,envp);return 0;使用POSIX IO实现计算文件大小#include <stdlib.h>#include <stdio.h>#include <errno.h>#include <fcntl.h>int my_callen ( int fd ) int len; if ( lseek( fd , 0 , SEEK_END ) = -1 ) perror( "lseek“); if ( ( len = lseek ( fd , 0 , SEEK_CUR )

31、 ) = -1 ) perror( "lseek“); return len;int main ( int argc , char * argv ) int len = -1; int fd; if ( argc < 2 ) perror ( "para“) ; if ( ( fd = open ( argv1 , O_RDONLY ) ) =-1 ) perror ( "open“) ; exit(EXIT_FAILURE); len = my_callen ( fd ) ; close(fd); if(len<0) perror ( "c

32、al“) ;elseprintf ( "There are %d bytes in file %s!n“ , len , argv1 ); return 0; 列出目录下的文件信息#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <dirent.h>#include <errno.h>int main ( int argc, char * argv ) if ( argc < 2 ) printf ( "usage:my_g

33、etdir dirnamen“ ) ; exit ( 0 ); if ( my_read ( argv1 ) < 0 ) exit ( EXIT_FAILURE ); return 0;int my_read ( const char * path ) DIR *dir ; struct dirent *ptr; if ( ( dir = opendir ( path ) ) = NULL ) perror (" opendir“);exit(EXIT_FAILURE); while ( ( ptr = readdir ( dir ) ) != NULL ) printf (

34、"file inode :%ldtt“ , ptr->d_ino ); printf ( "file name :%sn“ , ptr->d_name ); closedir ( dir ); return 0;例：生成多个子进程#include <stdio.h>#include <stdlib.h>#include <unistd.h>main() pid_t pid; int i=1;while(i<9) pid=fork();if(pid=0) printf("I'm no. %d proces

35、s, my pid is %d.n", i, getpid();if(i!=1)return 0;i+;由于父子进程执行顺序的不确定性，当子进程先于父进程退出时，子进程会留下一些资源来记录运行的信息，以提供给父进程进行访问。如果父进程没有调用wait或waitpid函数的话，则子进程将会一直保留这些信息，成为僵尸进程。如果父进程调了wait函数，子进程就不会成为僵尸进程。用孤儿进程是指因父亲进程先结束而导致一个子进程被init进程收养的进程。signal的应用#include <stdio.h>#include <signal.h>#include <u

36、nistd.h>#include <stdlib.h>void fun_ctrl_c();int main()(void)signal(SIGINT,fun_ctrl_c);printf("Now I'm starting.n");while(1)printf("this is an endless loop unless Ctrl+c are pressd!n");sleep(2);exit(0);void fun_ctrl_c()printf("tCtrl+c were pressed!n");print

37、f("t This is just an example for signal function!n");printf("treset signal SIGINTn");(void)signal(SIGINT,SIG_DFL);创建消息队列#include <stdio.h>#include <sys/ipc.h>#include <sys/types.h>int main()key_t key;key=ftok(".",1);printf("the key is %xn",ke

38、y);int id;id=msgget(key+1,IPC_CREAT|0666);printf("id=%dn",id);system(“ipcs”);删除消息队列#include <stdio.h>#include <sys/ipc.h>#include <sys/types.h>int main()key_t key;int id;key=ftok(".",1);id=msgget(key+1,IPC_CREAT|0666);printf("id=%dn",id);msgctl(id,IPC_

39、RMID,NULL);sytem(“ipcs”);将数组str中的数据写入文件strtext.txt中，每行一条数据；随后，将文件中的数据读入到数组out中，输出out数组的数据。#include <stdio.h>#include <stdlib.h>main() char str15="January","February","March","April","May", "June","July","August&qu

40、ot;,"september","October","November","December"char out1215;FILE *fp;int i;fp=fopen("strtext.txt","w");if(fp=NULL)printf("cant open file!n");exit(1); fwrite(str,15,12,fp); fclose(fp); printf("write data success!n");fp=fo

41、pen("strtext.txt","r"); if(fp=NULL)printf("cant open file!n"); exit(1);fread(out,15,12,fp); fclose(fp);printf("read data success!n"); printf("the data in array out are:n"); for(i=0;i<12;i+) printf("%sn",outi);fscanf函数实现scanf函数的功能#include

42、 <stdio.h>const int MAX_N = 21;int main()int i;char x;FILE *myfile = fopen("test.txt", "r"); if (myfile) for (i = 1; i <= MAX_N; i+) fscanf(myfile, "%c", &x)；printf("%c", x); return 0;将文件描述符转换为流对象#include <stdio.h>#include <stdlib.h>#i

43、nclude <unistd.h>#include <fcntl.h>#include <sys/stat.h>main() int fd;FILE *stream;unlink("test.txt"); fd=open("test.txt",O_CREAT|O_WRONLY,S_IREAD|S_IWRITE)stream=fdopen(fd,"w");if(stream=NULL) printf("fdopen failedn");else fprintf(stream, &q

44、uot;Hello worldn"); fclose(stream);printf("the content of the test.txt is:n"); system("cat test.txt"); return 0; 文件的创建，打开#include <fcntl.h>#include <stdio.h>#include <stdlib.h>main(int argc, char * argv ) int fd_open, fd_open_create, fd_create; if(fd_open=o

45、pen("/bin/ls",O_RDONLY) = -1)perror("open");exit(EXIT_FAILURE); printf ( "the file's descriptor is: %dn " , fd_open ); if(fd_open_create=open("./tmp",O_CREAT|O_EXCL,0644) = -1)perror("open");exit(EXIT_FAILURE); printf ( " the tmp1 file descr

46、iptor is: %dn" ,fd_open_create);if(fd_create=creat("./tmp2",0644) = -1 )perror("open");exit(EXIT_FAILURE); printf("the tmp2 file descriptor is: %dn",fd_create);close(fd_open); close(fd_open_create); close(fd_create); return 0;文件读写#include <stdio.h>#include &l

47、t;stdlib.h>#include <unistd.h>int main() char buf80; int n; n=read(STDIN_FILENO,buf,80);if(n<0) perror("read STDIN_FILENO"); exit(EXIT_FAILURE); write(STDOUT_FILENO,buf,n); printf("n");return 0;使用POSIX IO实现文件拷贝 #include <stdio.h>#include <stdlib.h>#include

48、 <fcntl.h>#include <string.h>#include <sys/types.h>main(int argc, char * argv) int fd_src,fd_des; char buf128;int num;if(argc!=3) printf("tje format must be: cp file_src file_des");exit(EXIT_FAILURE); if(fd_src=open(argv1,O_RDONLY)=-1) perror("open1");exit(EXIT_

49、FAILURE); if(fd_des=open(argv2,O_CREAT|O_EXCL|O_WRONLY,0644)=-1) perror("open2");exit(EXIT_FAILURE); do num=read(fd_src,buf,128);write(fd_des,buf,num);while(num=128);close(fd_src); close(fd_des);父子进程的交替执行int main() pid_t pid; printf(“Lets study fork function!n”); pid=fork(); switch(pid) ca

50、se -1: perror(“fork failure”); break; case 0: printf(“hellow, Im child process, my pid is %d, my parent is %d!n”, getpid(), getppid(); break;default:printf(“hi, Im parent process, my pid is %d!n”,getpid(); break; exit(0);父子进程读写文件#include <stdlib.h>#include <stdio.h>#include <unistd.h&

51、gt;#include <sys/stat.h>#include <sys/types.h>#include <fcntl.h>int main() int fd; pid_t pid; char buf45;if ( ( fd = open ( “code”, O_CREAT|O_RDWR|O_TRUNC, S_IRWXU ) ) < 0 ) perror ( "open error“ ); exit ( 0 ); pid = fork ( );switch ( pid ) case -1: perror ( "fork erro

52、r“ ); break; case 0: printf ( "child processn“ ); if (write(fd,"I'm child process. Daddy, do you see me?“,41 )<0) perror ( "child error“ ); exit ( 0 ); break; default : sleep ( 6 ); printf ( "nparent processn“ ); lseek ( fd, 0, SEEK_SET); if ( read ( fd, buf, 41) < 0 )

53、perror ( "parent error“ ); exit ( 0 ); printf("n%sn",buf); close(fd); break; 生成多个子进程#include <stdio.h>#include <stdlib.h>#include <unistd.h>main() pid_t pid; int i=1; while(i<9) pid=fork();if(pid=0) printf("I'm no. %d process, my pid is %d.n", i, get

54、pid(); if(i!=1)return 0;i+;产生一个孤儿进程#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <sys/types.h>int main ( ) pid_t pid; int k=3; pid = fork ( ); switch ( pid ) case -1: perror ( "fork errorn“ ); break;case 0 : while ( k > 0 ) printf ( "I'm ch

55、ild process, my PID is %d, my parent is %d.n", getpid ( ), getppid ( ) );sleep(1); k-;break;default : printf ( "I'm parent process, my PID is %d.n", getpid ( ) ); break; exit与return的区别C语言关键字与函数exit()在main函数退出时有相似之处，但两者有本质的区别：return 退出当前函数主体，exit()函数退出当前进程，因此，在main函数里面return(0)和exi

56、t(0)完成一样的功能。return仅仅从子函数中返回，而子进程用exit()退出，调用exit()时要调用一段终止处理程序，然后关闭所有I/O流。守护进程的实现 #include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <signal.h>#include <fcntl.h>#include <sys/syslog.h>#include<sys/param.h>#include<sys/types.h>#include <

57、;sys/stat.h>int init_daemon(const char *pname,int facility) int pid;int i;signal(SIGTTOU,SIG_IGN);signal(SIGTTIN,SIG_IGN);signal(SIGTSTP,SIG_IGN);signal(SIGHUP,SIG_IGN);pid=fork();if(pid>0)exit(EXIT_SUCCESS);else if(pid<0)perror("fork");exit(EXIT_FAILURE);setsid();pid=fork();if(pi

58、d>0)exit(EXIT_SUCCESS);else if(pid<0)perror("fork");exit(EXIT_FAILURE);for(i=0;i<NOFILE;i+)close(i);open("/dev/null",O_RDONLY);open("/dev/null",O_RDWR);open("/dev/null",O_RDWR);chdir("/");umask(0);signal(SIGCHLD,SIG_IGN);openlog(pname,LOG_PI

59、D,facility);return;main(int argc,char * argv) FILE *fp;time_t ticks;init_daemon(argv0,LOG_KERN);while(1)sleep(1);ticks=time(NULL);syslog(LOG_INFO,"%s",asctime(localtime(&ticks);父子进程通过无名管道通信#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <sys/wait.h>#include <unistd.h>#include