Directory and file attributes--"Unix/linux Programming Practice Tutorial" reading notes

1. LS produces a list of file names, which is roughly how it works:

Open directory+-> Read entry        -end of dir?-+|__ display file Info                |    Close Directory   <--------------+

2, the directory is a special kind of file, its content is the name of the file and directory. Unlike normal files, catalog files are never empty, and each directory contains at least 2 special items,"."and "..", where"." Not current directory,"..." Represents the previous level of the directory.

3, man 3 Readdir

#include <sys/types.h> #include <dirent.h>dir *opendir (const char *dir_name); struct dirent *readdir (DIR * dir_name); int Readdir_r (dir *dir_ptr, struct dirent *entry,    struct dirent **result); Long Telldir (dir *dir_ptr); void Seekdir (dir *dir_ptr, long location), void Rewinddir (dir *dir_ptr); int Closedir (dir *dir_ptr);

4, LS algorithm:

Main ()    opendir while    (readdir)        print d_name    closedir

5. Get the file information with stat:

Man 2 stat

#include <sys/stat.h>int res = stat (const char *path, struct stat *buf);    /* Return 0 for success, 1 for error */

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 filesystem 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 * *};

6, man Getpwuid

7, SUID Bit tells the kernel, run this program is considered by the owner of the file to run the program, Sgid bit tells the kernel, run this program when the file belongs to the group to run the program, sticky bit for the file, in the early Exchange (swap) technology, The directory is designed to hold temporary files, such as/tmp.

Ls-l sample-rwsr-sr-t   1   root root 2345    Jul 00:45    sample

8. Setting and modifying properties of a file

#include <sys/types.h> #include <sys/stat.h>int res = chmod (const char *path, mod_t mode); int res = chmod (int f D, mode_t mode);    /* On success, 0 is returned. On error, 1 was returned and       errno is set appropriately */

#include <unistd.h>int chown (const char *path, uid_t owner, gid_t Group); int Fchown (int fd, uid_t owner, gid_t Group ); int Lchown (const char *path, uid_t owner, gid_t Group);    /* On success, 0 is returned. On error, 1 was returned and       errno is set appropriately */

9, modify the last modified time and last access time:

Mans Utime

10. Modify the file name

Mans 2 Rename