基于/proc伪文件系统的读取系统常见内核状态信息

linux实验，需要学生掌握linux下文件的读写。我做了一个基于/proc伪文件系统的读取系统内核信息的一个小程序。

读取cpu信息-------/proc/cpuinfo

读取内存信息-------/proc/meminfo

读取挂载设备-----/proc/mounts

读取已经加载的设备并分类---------/proc/devices

读取支持的文件系统--------/proc/filesystems

读取加载的模块----------/proc/modules

读取系统的版本信息-----------/proc/version

启动时传递给kernel的参数----------/proc/cmdline

这个程序用到了自己写的一个按行读取的函数readline

------------------》》》》》》》》》》》》》按行读取的readline

#include <stdio.h>#include <stdlib.h>#include <sys/types.h>#include <unistd.h>#include <fcntl.h>#define CPU_INFO_FILE "/proc/cpuinfo"#define MEMORY_INFO_FILE "/proc/meminfo"#define MOUNTS_INFO_FILE "/proc/mounts"#define DEVICES_INFO_FILE "/proc/devices"#define FILESYSTEM_INFO_FILE "/proc/filesystems"#define MODULES_INFO_FILE "/proc/modules"#define VERSION_INFO_FILE "/proc/version"#define CMDLINE_INFO_FILE "/proc/cmdline"void display_help();int readline(int fd,char** buff);int main(int argc,char* argv[]){intvfile;//file pointint rel;// the length of read from fileint count=0;charoption,*buff=NULL;//charge the number of arguments//we need a argument to help choose a operate//if the number of arguments is less two ,there is no arguments//if the number of arguments is greater than two ,some arguments are superluousif(argc<2){printf("\033[31m the arguments too less \033[0m \n");display_help();exit(1);} if(argc>2){printf("\033[31m the arguments too much \033[0m \n");display_help();exit(1);}//get optionoption=argv[1][0];switch(option){case 'c':vfile=open(CPU_INFO_FILE,O_RDONLY);break;case 'm':vfile=open(MEMORY_INFO_FILE,O_RDONLY);break;case 'n':vfile=open(MOUNTS_INFO_FILE,O_RDONLY);break;case 'd':vfile=open(DEVICES_INFO_FILE,O_RDONLY);break;case 'f':vfile=open(FILESYSTEM_INFO_FILE,O_RDONLY);break;case 'l':vfile=open(MODULES_INFO_FILE,O_RDONLY);break;case 'v':vfile=open(VERSION_INFO_FILE,O_RDONLY);break;case 'e':vfile=open(CMDLINE_INFO_FILE,O_RDONLY);break;case 'h':display_help();exit(0);break;default:display_help();exit(0);}if(vfile<0){printf("open file error\n");exit(1);}while((rel=readline(vfile,&buff))>0){printf("%s",buff);free(buff);count++;if(count%10==0){printf(":");option=getchar(); printf("\033[1A");if(option=='q'){close(vfile);exit(0);}}}close(vfile);return 0;}void display_help(){printf("--------------------------------\n");printf("welcome to use the system info viewer\n");printf("--------------------------------\n");printf("\e[1mNAME\e[0mget host info\n\n");printf("\e[1mSYNOPSIS\e[0mgethostinfo  option\n\n");printf("\e[1mOPTION\e[0m\n\n");printf("\e[1mc\e[0m \nget the cpu info\n");printf("m\nget the memory info\n");printf("n\nget the list of mounts info\n");printf("d\nget the list of devices  info\n");printf("f\nget the list of filesystem supported\n ");printf("l\nget the modules\n");printf("v\nget the system version\n");printf("e\nget the cmdline info\n\n");printf("h\nhelp\n");printf("--------------------------------\n");}int readline(int fd,char** buff){        int rl=-1;        char c;        long maxlength=128;        long count=0;        if(fd<0)        {                printf("open file error\n");                exit(0);        }        *buff=(char*)malloc(sizeof(char)*maxlength);if(*buff==NULL){printf("allocate memory error");close(fd);exit(1);}        while((rl=read(fd,&c,1))>0)        {                if(count==maxlength)                {                        maxlength+=128;                        *buff=(char*)realloc(*buff,maxlength);                        if(buff==NULL)                        {                                printf("allocate memory error\n");                                close(fd);                                exit(0);                        }                }                (*buff)[count++]=c;  if(c=='\n' || c==EOF)                {                        break;                }        }        (*buff)[count]='\0';        return count;}

当程序不带参数的时候会输出帮助，有语法提示和选项提示。

运行结果：