用c语言实现Linux命令ls操作

主要的流程是解析输入和调用相关的函数获得文件详细信息。

能够实现的命令格式有：ls –l (-d –R –a –I –al -ai) [filename1]([filename2] ……)。

演示效果如图所示：

代码如下：

#include <stdio.h>#include <sys/types.h>#include <dirent.h>#include <sys/stat.h>#include <pwd.h>#include <grp.h>#include <unistd.h>#include <string.h>#define LS_NONE 0#define LS_L 101#define LS_R 102#define LS_D 103#define LS_I 104#define LS_A 200#define LS_AL (LS_A+LS_L)#define LS_AI (LS_A+LS_I)// 展示单个文件的详细信息void show_file_info(char* filename, struct stat* info_p){    char* uid_to_name(), *ctime(), *gid_to_name(), *filemode();    void mode_to_letters();    char modestr[11];    mode_to_letters(info_p->st_mode, modestr);    printf("%s", modestr);    printf(" %4d", (int) info_p->st_nlink);    printf(" %-8s", uid_to_name(info_p->st_uid));    printf(" %-8s", gid_to_name(info_p->st_gid));    printf(" %8ld", (long) info_p->st_size);    printf(" %.12s", 4 + ctime(&info_p->st_mtime));    printf(" %s\n", filename);}void mode_to_letters(int mode, char str[]){    strcpy(str, "----------");    if (S_ISDIR(mode))    {        str[0] = 'd';    }    if (S_ISCHR(mode))    {        str[0] = 'c';    }    if (S_ISBLK(mode))    {        str[0] = 'b';    }    if ((mode & S_IRUSR))    {        str[1] = 'r';    }    if ((mode & S_IWUSR))    {        str[2] = 'w';    }    if ((mode & S_IXUSR))    {        str[3] = 'x';    }    if ((mode & S_IRGRP))    {        str[4] = 'r';    }    if ((mode & S_IWGRP))    {        str[5] = 'w';    }    if ((mode & S_IXGRP))    {        str[6] = 'x';    }    if ((mode & S_IROTH))    {        str[7] = 'r';    }    if ((mode & S_IWOTH))    {        str[8] = 'w';    }    if ((mode & S_IXOTH))    {        str[9] = 'x';    }}char* uid_to_name(uid_t uid){    struct passwd* getpwuid(),* pw_ptr;    static char numstr[10];    if((pw_ptr = getpwuid(uid)) == NULL)    {        sprintf(numstr,"%d",uid);        return numstr;    }    else    {        return pw_ptr->pw_name;    }}char* gid_to_name(gid_t gid){    struct group* getgrgid(),* grp_ptr;    static char numstr[10];    if(( grp_ptr = getgrgid(gid)) == NULL)    {        sprintf(numstr,"%d",gid);        return numstr;    }    else    {        return grp_ptr->gr_name;    }}void do_ls(char dirname[],int mode){    DIR* dir_ptr;    struct dirent* direntp;    if ((dir_ptr = opendir(dirname)) == NULL)    {        fprintf(stderr, "ls2: cannot open %s \n", dirname);    }    else    {        if(mode==LS_D)        {            printf("%s\n", dirname);        }        else        {            char dirs[20][100];            int dir_count = 0;                        while ((direntp = readdir(dir_ptr)) != NULL)            {                if(mode < 200 && direntp->d_name[0]=='.')                {                    continue;                }                char complete_d_name[200];  // 文件的完整路径                strcpy (complete_d_name,dirname);                strcat (complete_d_name,"/");                strcat (complete_d_name,direntp->d_name);                                struct stat info;                if (stat(complete_d_name, &info) == -1)                {                    perror(complete_d_name);                }                else                {                    if(mode == LS_L||mode == LS_AL)                    {                        show_file_info(direntp->d_name, &info);                    }                    else if(mode == LS_A||mode == LS_NONE||mode == LS_I||mode == LS_AI)                    {                        if(mode == LS_I||mode == LS_AI)                        {                            printf("%llu ", direntp->d_ino);                        }                        printf("%s\n", direntp->d_name);                    }                    else if(mode == LS_R)                    {                        if(S_ISDIR(info.st_mode))                        {                            printf("%s\n", direntp->d_name);                            strcpy (dirs[dir_count],complete_d_name);                            dir_count++;                        }                        else                        {                            printf("%s\n", direntp->d_name);                        }                    }                }            }            if(mode == LS_R)            {                int i=0;                printf("\n");                for(;i<dir_count;i++){                    printf("%s:\n", dirs[i]);                    do_ls(dirs[i],LS_R);                    printf("\n");                }            }        }        closedir(dir_ptr);    }}// 解析一个单词参数，如-l，-iint analyzeParam(char* input){    if(strlen(input)==2)    {        if(input[1]=='l') return LS_L;        if(input[1]=='a') return LS_A;        if(input[1]=='d') return LS_D;        if(input[1]=='R') return LS_R;        if(input[1]=='i') return LS_I;    }    else if(strlen(input)==3)    {        if(input[1]=='a'&& input[2]=='l') return LS_AL;        if(input[1]=='a'&& input[2]=='i') return LS_AI;    }    return -1;}int main(int ac,char* av[]){    if(ac == 1)    {        do_ls(".",LS_NONE);    }    else    {        int mode = LS_NONE; // 默认为无参数ls        int have_file_param = 0; // 是否有输入文件参数        while(ac>1)        {            ac--;            av++;            int calMode = analyzeParam(*av);            if(calMode!=-1)            {                mode+=calMode;            }            else            {                have_file_param = 1;                do                {                    printf("%s:\n", *av);                    do_ls(*av,mode);                    printf("\n");                    ac--;                    av++;                }while(ac>=1);            }        }        if (!have_file_param)        {            do_ls(".",mode);        }            }     }