《计算机操作系统》实验指导苏州科技学院电子与信息工程系软件教研室二OO二年九月示例代码第一部分LINUX操作系统平台实验一命令解释程序示例程序minishell.c//文件名minishell.cpp//功能小型SHELL命令解释程序//开发环境#define true 1#define flase 0#include <stdio.h>#include <string.h>#include <stdlib.h>void main(){char cmdl[80];char *scwt[]={"exit","dir","time"};static int cmdnum=3; //可用的命令数char cmd[80];int j,n;while(true){printf("Please input command: ");gets(cmdl); //取命令行输入n=strcspn(cmdl," "); //取命令命令部分if (n>0||strlen(cmdl)>0){ strncpy(cmd,cmdl,n);cmd[n]='\0';for(j=0;j<cmdnum;j++)if (strcmp(cmd,scwt[j])==0)break;if (j==0) //是exit命令?exit(0);if (j<cmdnum) //其他合法命令{system(cmdl);continue;}printf("Bad command!\n"); //命令错}}}实验二进程管理fork()调用示例#include <stdio.h>main(){int p1,p2;while ((p1=fork())==-1);if (p1==0) //是子进程？putchar('b');else //父进程{putchar('a');}}实验三进程间通信1）pipe()调用示例#include<stdio.h>main(){int id,fd[2];char buf[50],s[50];pipe(fd);while ((id=fork())==-1);if (id==0){sprintf(buf,"Child is sending message!");write(fd[1],buf,50);exit(0);}else{wait(0);read(fd[0],s,50);printf("%s\n",s);exit(0);}}2）共享存储器示例shm_sample.c#include <stdio.h>#include <sys/types.h>#include <sys/ipc.h>#include <sys/shm.h>#define SEGSIZE 100main(int argc, char *argv[]){ key_t key;int shmid, cntr;char *segptr;if(argc == 1)usage(); /* Create unique key via call to ftok() */key = ftok(".", 'S');/* Open the shared memory segment - create if necessary */if((shmid = shmget(key, SEGSIZE, IPC_CREAT|IPC_EXCL|0666)) == -1){printf("Shared memory segment exists - opening as client\n");/* Segment probably already exists - try as a client */if((shmid = shmget(key, SEGSIZE, 0)) == -1){perror("shmget");exit(1);}}else{printf("Creating new shared memory segment\n");}/* Attach (map) the shared memory segment into the current process */if((segptr = shmat(shmid, 0, 0)) == -1){perror("shmat");exit(1);}switch(tolower(argv[1][0])){case 'w': writeshm(shmid, segptr, argv[2]);break;case 'r': readshm(shmid, segptr);break;case 'd': removeshm(shmid);break;case 'm': changemode(shmid, argv[2]);break;default: usage();}}writeshm(int shmid, char *segptr, char *text){strcpy(segptr, text);printf("Done...\n");}readshm(int shmid, char *segptr){printf("segptr: %s\n", segptr);}removeshm(int shmid){shmctl(shmid, IPC_RMID, 0);printf("Shared memory segment marked for deletion\n");}changemode(int shmid, char *mode){struct shmid_ds myshmds;/* Get current values for internal data structure */shmctl(shmid, IPC_STA T, &myshmds); /* Display old permissions */printf("Old permissions were: %o\n", myshmds.shm_perm.mode);/* Convert and load the mode */sscanf(mode, "%o", &myshmds.shm_perm.mode); /* Update the mode */ shmctl(shmid, IPC_SET, &myshmds);printf("New permissions are : %o\n", myshmds.shm_perm.mode);}usage(){fprintf(stderr, "shm_sample - A utility for tinkering with shared memory\n");fprintf(stderr, "\nUSAGE: shmtool (w)rite <text>\n");fprintf(stderr, " (r)ead\n");fprintf(stderr, " (d)elete\n");fprintf(stderr, " (m)ode change <octal mode>\n");exit(1);}3）消息队列使用示例(1) message.h/* message.h*/#ifndef MESSAGE_H#define MESSAGE_Hstruct mymsgbuf{long mtype;char mtext[256];};#endif(2) msg_server.c/*msg_server.c*/#include <stdio.h>#include <stdlib.h>#include <string.h>#include <signal.h>#include <sys/msg.h>#include <sys/ipc.h>#include "message.h"int msqid=-1;void sig_handle(int signo){/*软中断*/if (msqid!=-1)msgctl(msqid,IPC_RMID,NULL);printf("server quit...\n");exit(0);}int main(){struct mymsgbuf msgbuf;int left,right;char c;int length;if ((msqid=msgget(999,0666))!=-1){msgctl(msqid,IPC_RMID,NULL);}if ((msqid=msgget(999,IPC_CREAT|0666))==-1){printf("error:getmsg\n");exit(1);}signal(SIGINT,sig_handle); /*LINUX置软中断—CTRL-D*/for (;;){if (msgrcv(msqid,&msgbuf,256,1L,0)==-1){printf("error:msgrcv\n");exit(1);}length=strlen(msgbuf.mtext);left=0;right=length-1;while(left<right){c=msgbuf.mtext[left];msgbuf.mtext[left]=msgbuf.mtext[right];msgbuf.mtext[right]=c;left++;right--;}msgbuf.mtext[length]='\0';msgbuf.mtype=2;if (msgsnd(msqid,&msgbuf,256,0)==-1){printf("error:msgsnd");exit(1);}}msgctl(msqid,IPC_RMID,NULL);exit(0);}(3) msg_client.c/*msg_client.c*/#include <stdio.h>#include <stdlib.h>#include <string.h>#include <sys/msg.h>#include <sys/ipc.h>#include "message.h"int main(){struct mymsgbuf msgbuf;int msqid;if ((msqid=msgget(999,0666))==-1){printf("Server is not running\n");exit(1);}printf("Input a line:");scanf("%s",msgbuf.mtext);msgbuf.mtype=1;if (msgsnd(msqid,&msgbuf,256,0)==-1){printf("error:msgsnd\n");exit(1);}if (msgrcv(msqid,&msgbuf,256,2L,0)==-1){printf("error:msgrcv\n");exit(1);}printf("The reversed line is:%s\n",msgbuf.mtext);exit(0);}实验四存储管理示例程序(注意阅读并分析可能存在的问题)#define TRUE 1#define FALSE 0#define INV ALID -1#define null 0#define total_instruction 320 /*指令流长*/#define total_vp 32 /*虚页长*/#define clear_period 50 /*清零周期*/typedef struct{ /*页面结构*/ int pn,pfn,counter,time;}pl_type;pl_type pl[total_vp]; /*页面数组*/struct pfc_struct{ /*页面控制结构*/ int pn,pfn;struct pfc_struct *next;};typedef struct pfc_struct pfc_type;pfc_type pfc[total_vp],*freepf_head,*busypf_head,*busypf_tail;int diseffect,a[total_instruction];int page[total_instruction], offset[total_instruction];void initialize(int total_pf);void FIFO(int total_pf);void LRU(int total_pf);void OPT(int total_pf);void LFU(int total_pf);void NUR(int total_pf);#include <stdlib.h>#include <stdio.h>#include <time.h>main(){int S,i;srand( (unsigned)time( NULL ) );/* srand(getpid()*10);*//*由于每次运行时进程号不同，故可用来作为初始化随机数的"种子"*/S=(float)319*rand()/32767+1;for(i=0;i<total_instruction;i+=4) /*产生指令队列*/{a[i]=S; /*任选一指令访问点*/a[i+1]=a[i]+1; /*顺序执行一条指令*/a[i+2]=(float)a[i]*rand()/32767; /*执行前地址指令m'*/a[i+3]=a[i+2]+1; /*执行后地址指令*/S=(float)rand()*(318-a[i+2])/32767+a[i+2]+2;}for(i=0;i<total_instruction;i++) /*将指令序列变换成页地址流*/{page[i]=a[i]/10;offset[i]=a[i]%10;}for(i=4;i<=32;i++) /*用户内存工作区从4个页面到32个页面*/ {printf("%2d page frames",i);FIFO(i);LRU(i);OPT(i);LFU(i);NUR(i);printf("\n");}return(0);}//void FIFO(total_pf) /*FIFO（First In First Out) ALOGRITHM*/ //int total_pf; /*用户进程的内存页面数*/void FIFO(int total_pf)//int total_pf;{int i;pfc_type *p;initialize(total_pf);busypf_head=busypf_tail=NULL;for (i=0;i<total_instruction;i++){if (pl[page[i]].pfn==INV ALID){diseffect+=1;if (freepf_head==NULL){p=busypf_head->next;pl[busypf_head->pn].pfn=INV ALID;freepf_head=busypf_head;freepf_head->next=NULL;busypf_head=p;}p=freepf_head->next;freepf_head->next=NULL;freepf_head->pn=page[i];pl[page[i]].pfn=freepf_head->pfn;if (busypf_tail==NULL)busypf_head=busypf_tail=freepf_head;else{busypf_tail->next=freepf_head;busypf_tail=freepf_head;}freepf_head=p;}}printf(" FIFO:%6.4f",1-(float)diseffect/320);}void LRU(int total_pf)//int total_pf;{int min,minj,i,j,present_time;initialize(total_pf);present_time=0;for(i=0;i<total_instruction;i++){if (pl[page[i]].pfn=INV ALID){diseffect++;if (freepf_head==NULL){min=32767;for(j=0;j<total_vp;j++)if (min>pl[j].time && pl[j].pfn!=INV ALID){min=pl[j].time;minj=j;}freepf_head=&pfc[pl[minj].pfn];pl[min].pfn=INV ALID;pl[min].time=-1;freepf_head->next=NULL;}pl[page[i]].pfn=freepf_head->pfn;pl[page[i]].time=present_time;freepf_head=freepf_head->next;}elsepl[page[i]].time=present_time;present_time++;}printf(" LRU:%6.4f",1-(float)diseffect/320);}void NUR(int total_pf)//int total_pf;{int i,j,dp,cont_flag,old_dp;// pfc_type *t;initialize(total_pf);dp=0;for(i=0;i<total_instruction;i++){if (pl[page[i]].pfn==INV ALID) /*页面失效*/{diseffect++;if (freepf_head==NULL) /*无空闲页面*/{cont_flag=TRUE;old_dp=dp;while(cont_flag)if (pl[dp].counter==0&&pl[dp].pfn!=INV ALID)cont_flag=FALSE;else{dp++;if (dp==total_vp)dp=0;if (dp==old_dp)for (j=0;j<total_vp;j++)pl[j].counter=0;}freepf_head=&pfc[pl[dp].pfn];pl[dp].pfn=INV ALID;freepf_head->next=NULL;}pl[page[i]].pfn=freepf_head->pfn;freepf_head=freepf_head->next;}elsepl[page[i]].counter=1;if (i%clear_period==0)for(j=0;j<total_vp;j++)pl[j].counter=0;}printf(" NUR:%6.4f",1-(float)diseffect/320);}void OPT(int total_pf) /*OPT（Optional Replacement) ALOGRITHM*/ //int total_pf;{int i,j,max,maxpage,d,dist[total_vp];pfc_type *t;initialize(total_pf);for(i=0;i<total_instruction;i++){if (pl[page[i]].pfn==INV ALID){diseffect++;if (freepf_head==NULL){for(j=0;j<total_vp;j++)if (pl[j].pfn!=INV ALID)dist[j]=32767;elsedist[j]=0;d=1;for(j=i+1;j<total_instruction;j++){if (pl[page[j]].pfn!=INV ALID)dist[page[j]]=d;d++;}max=-1;for(j=0;j<total_vp;j++)if (max<dist[j]){max=dist[j];maxpage=j;}freepf_head=&pfc[pl[maxpage].pfn];freepf_head->next=NULL;pl[maxpage].pfn=INV ALID;}pl[page[i]].pfn=freepf_head->pfn;freepf_head=freepf_head->next;}}printf(" OPT:%6.4f",1-(float)diseffect/320);}void LFU(int total_pf) /*LFU（leat Frequently Used) ALOGRITHM*/ //int total_pf;{int i,j,min,minpage;pfc_type *t;initialize(total_pf);for(i=0;i<total_instruction;i++){if (pl[page[i]].pfn==INV ALID){diseffect++;if (freepf_head==NULL){min=32767;for(j=0;j<total_vp;j++){if (min>pl[j].counter&&pl[j].pfn!=INV ALID){min=pl[j].counter;minpage=j;}pl[j].counter=0;}freepf_head=&pfc[pl[minpage].pfn];pl[minpage].pfn=INV ALID;freepf_head=freepf_head->next;}elsepl[page[i]].counter++;}}printf(" LFU:%6.4f",1-(float)diseffect/320);}void initialize(int total_pf) /*初始化相关数据结构*///int total_pf; /*用户进程的内存页面数*/{int i;diseffect=0;for(i=0;i<total_vp;i++){pl[i].pn=i;pl[i].pfn=INV ALID; /*置页面控制结构中的页号，页面为空*/pl[i].counter=0; /*页面控制结构中的访问次数为0，时间为-1*/pl[i].time=-1;}for(i=1;i<total_pf;i++){pfc[i-1].next=&pfc[i];pfc[i-1].pfn=i-1;} /*建立pfc[i-1] 和pfc[i]之间的链接*/pfc[total_pf-1].next=NULL;pfc[total_pf-1].pfn=total_pf-1;freepf_head=&pfc[0]; /*空页面队列的头指针为pfc[0]*/}实验五设备管理一、实验步骤:LINUX中，模块可以用C语言编写，用gcc编译成目标文件（不进行链接，作为*.o文件存在），为此需要在gcc命令行里加上-c的参数。
