文件和目录

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函数

1.stat

获取文件/目录属性信息

 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>
 int stat(const char *path, struct stat *buf);     //主要掌握这一个，函数返回一个与此命名有关的信息结构
 int fstat(int fd, struct stat *buf);
 int lstat(const char *path, struct stat *buf);

           struct stat {
               dev_t     st_dev;     /* ID of device containing file */
               ino_t     st_ino;     /* inode number */
               mode_t    st_mode;    /* protection */
               nlink_t   st_nlink;   /* number of hard links */
               uid_t     st_uid;     /* user ID of owner */
               gid_t     st_gid;     /* group ID of owner */
               dev_t     st_rdev;    /* device ID (if special file) */
               off_t     st_size;    /* total size, in bytes */
               blksize_t st_blksize; /* blocksize for file system I/O */
               blkcnt_t  st_blocks;  /* number of 512B blocks allocated */
               time_t    st_atime;   /* time of last access */
               time_t    st_mtime;   /* time of last modification */
               time_t    st_ctime;   /* time of last status change */
           };

        struct passwd *uid = getpwuid(b.st_uid); //获得用户名
        struct group *gid = getgrgid(b.st_gid);//获得所属组名

        struct tm *t = localtime(&b.st_ctime);//获取时间
        printf("%2d月,%2d日,%2d点,%2d分,%2d秒  ",t->tm_mon,t->tm_mday,t->tm_hour,t->tm_min,t->tm_sec);

/**************自己写的实现ls -l功能*******************************/

#include<stdio.h>#include<fcntl.h>#include<sys/stat.h>#include<sys/types.h>#include<unistd.h>#include<dirent.h>#include<pwd.h>#include<grp.h>#include<time.h>int main(){    DIR *f = opendir(".");    struct dirent *r;    struct stat b;    while( r = readdir(f) )    {        if( 0 > stat(r->d_name,&b))        {            perror("stat");            return -1;        }        struct passwd *uid = getpwuid(b.st_uid); //获得用户名        struct group *gid = getgrgid(b.st_gid);//获得所属组名        printf("userID:%s  ",uid->pw_name);        printf("groupID:%s  ",gid->gr_name);                //******************文件类型**************        switch(b.st_mode & S_IFMT)//文件类型的位遮罩S_TFMT        {            case S_IFREG:                printf("-");                break;            case S_IFDIR:                printf("d");                break;            case S_IFCHR:                printf("c");                break;            case S_IFBLK:                printf("b");                break;            case S_IFIFO:                printf("p");                break;            case S_IFLNK:                printf("c");                break;            case S_IFSOCK:                printf("s");                break;         }//***********************文件的权限**************        (b.st_mode & S_IRUSR?printf("r"):printf("-"));        (b.st_mode & S_IWUSR?printf("w"):printf("-"));        (b.st_mode & S_IXUSR?printf("x"):printf("-"));        (b.st_mode & S_IRGRP?printf("r"):printf("-"));        (b.st_mode & S_IWGRP?printf("w"):printf("-"));        (b.st_mode & S_IXGRP?printf("x"):printf("-"));        (b.st_mode & S_IROTH?printf("r"):printf("-"));        (b.st_mode & S_IWOTH?printf("w"):printf("-"));        (b.st_mode & S_IXOTH?printf("x  "):printf("-  "));        //**********文件大小************************        printf("%5ld  ",b.st_size);        //************时间*******************************        struct tm *t = localtime(&b.st_ctime);        printf("%2d月,%2d日,%2d点,%2d分,%2d秒  ",t->tm_mon,t->tm_mday,t->tm_hour,t->tm_min,t->tm_sec);//************文件名字***************        printf("%s",r->d_name);        printf("\n");    }        closedir(f);    return 0;}

/*******************标准点的********************************/

#include <stdio.h>#include <string.h>#include <stdlib.h>#include <strings.h>#include <sys/types.h>#include <sys/stat.h>#include <dirent.h>#include <pwd.h>#include <grp.h>#include <time.h>void getfiletype(mode_t m, char *type){if (S_ISREG(m)) *type = '-';else if (S_ISDIR(m))*type = 'd';else if (S_ISCHR(m))*type = 'c';else if (S_ISBLK(m))*type = 'b';else if (S_ISFIFO(m))*type = 'p';else if (S_ISLNK(m))*type = 'l';else if (S_ISSOCK(m))*type = 's';}void getfilemode(mode_t m, char *mode){if (m & S_IRUSR)mode[0] = 'r';if (m & S_IWUSR)mode[1] = 'w';if (m & S_IXUSR)mode[2] = 'x';if (m & S_IRGRP)mode[3] = 'r';if (m & S_IWGRP)mode[4] = 'w';if (m & S_IXGRP)mode[5] = 'x';if (m & S_IROTH)mode[6] = 'r';if (m & S_IWOTH)mode[7] = 'w';if (m & S_IXOTH)mode[8] = 'x';}void getfileusrname(uid_t uid, char *usrname){struct passwd *pw = getpwuid(uid);strcpy(usrname, pw->pw_name);}void getfilegrpname(gid_t gid, char *grpname){struct group *grp = getgrgid(gid);strcpy(grpname, grp->gr_name);}void getfiletime(time_t ctime, char *filetime){struct tm *tm = localtime(&ctime);sprintf(filetime, "%2d月 %2d %2d:%2d", tm->tm_mon+1, tm->tm_mday, \tm->tm_hour, tm->tm_min);}int main(){DIR *dirp = opendir(".");struct dirent *file;struct stat buf;while (file = readdir(dirp)) {if (0 > stat(file->d_name, &buf)) {perror("stat");break;}char type;getfiletype(buf.st_mode, &type);char mode[9] = {0};memset(mode, '-', sizeof(mode));getfilemode(buf.st_mode, mode);char usrname[10];getfileusrname(buf.st_uid, usrname);char grpname[10];getfilegrpname(buf.st_gid, grpname);char filetime[20];getfiletime(buf.st_ctime, filetime);fprintf(stdout, "%c%9s %2d %10s %10s %6ld %15s %s\n", type, mode, buf.st_nlink, usrname, grpname, buf.st_size, filetime, file->d_name);}return 0;}

2.opendir

打开目录

#include <sys/types.h>
#include <dirent.h>
DIR *opendir(const char *name);

成功返回DIR*类型的目录流，失败返回NULL

3.readdir

读取目录

#include <dirent.h>
struct dirent *readdir(DIR *dirp);

成功返回下个目录进入点，失败或者到达目录文件尾返回NULL

struct dirent {
               ino_t          d_ino;       /* inode number */
               off_t          d_off;       /* offset to the next dirent */
               unsigned short d_reclen;    /* length of this record */
               unsigned char  d_type;      /* type of file; not supported
                                                              by all file system types */
               char           d_name[256]; /* filename */
                      };

DIR *f = opendir(".");//打开当前目录
struct dirent *r;
struct stat b;
while(r = readdir(f)) //读取目录

{printf("%s",r->d_name);}//目录下的成员名

4.closedir

关闭目录

#include <sys/types.h>
#include <dirent.h>
int closedir(DIR *dirp);

关闭成功返回0，失败返回-1，并设置errno