"Linux C learn Stat" Get the properties of a file

NAME

Stat Get file properties

This function is located in the <sys/stat.h> header file.

Function Prototypes:

int  stat (const char *path, struct stat *buf);

Number of references:

Path file paths + file name

BUF Pointer to buffer

return value:

-1 encountered an error

0 successful return

Function Effect:

Copy the information from the path file into the struct that the pointer buf refers to.

Descriptive narrative

Stat structure:

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 * *           };

dev_t Include the ID of the device file

St_ino I junction

St_mode file types and license permissions

St_nline File links

St_uid ID of all users

St_gid ID of the owning group

St_rdev Device ID (assuming specified file)

The number of bytes that the st_size occupies

St_blksize File system I/O block size

St_block allocated for 512B size

St_atime Last interview time

St_mtime Last modification time

St_ctime state last changed time

The following POSIX macros define the file types used to check the St_mode domain

           S_isreg (M)  is a regular file?           S_isdir (m)  folder?           S_ISCHR (m)  character device?           S_ISBLK (m)  block device?           S_isfifo (m) FIFO?           S_islnk (m)  symbolic link?  (not in posix.1-1996.)           S_issock (m) sockets?  (not in posix.1-1996.)

The following flags are used for the St_mode domain:

           S_IFMT 0170000 bit mask for the file type bit fields S_ifsock 0140000 socket s_if           LNK 0120000 Symbolic Link s_ifreg 0100000 regular file s_ifblk 0060000 block device           S_ifdir 0040000 directory s_ifchr 0020000 character device S_ififo 0010000 FIFO S_isuid 0004000 set-user-id bit s_isgid 0002000 set-group-id bit (see below) S_ISV    TX 0001000 sticky bit (see below) S_irwxu 00700 mask for file owner permissions S_irusr     00400 owner has Read permission s_iwusr 00200 owner have write permission S_ixusr 00100     Owner have execute permission s_irwxg 00070 mask for group permissions S_irgrp 00040 Group has Read permission S_iwgrp 00020 Group have write permission S_ixgrp 00010 Group H   As Execute permission        S_irwxo 00007 Mask for permissions to others (not in group) S_iroth 00004 others has Rea D Permission S_iwoth 00002 Others has write permission S_ixoth 00001 others have execut E permission

Instance:

#include <stdio.h> #include <sys/types.h> #include <sys/stat.h> #include <time.h> #include <        Stdlib.h>int Main (int argc, char *argv[]) {struct STAT info;        if (argc! = 2) {fprintf (stderr, "Usage:%s <pathname>\n", argv[0]);    Exit (Exit_failure);        } if (stat (argv[1], &info) = =-1) {perror ("stat");    Exit (Exit_failure);                  } printf ("File type;    ");       Switch (Info.st_mode & s_ifmt) {case s_ifblk:printf ("Block device\n");        Break   Case s_ifchr:printf ("character device\n");        Break          Case s_ifdir:printf ("directory\n");        Break          Case s_ififo:printf ("FIFO pipe\n");        Break            Case s_iflnk:printf ("symlink\n");        Break       Case s_ifreg:printf ("regular file\n");        Break             Case s_ifsock:printf ("socket\n");        Break            default:printf ("unknown\n");    Break } printf("I-node Number:%ld\n", (long) Info.st_ino);    printf ("Mode:%lo (octal) \ n", (unsigned long) info.st_mode);    printf ("Link count:%ld\n", (long) info.st_nlink);    printf ("Ownership:uid=%ld gid=%ld\n", (Long) Info.st_uid, (long) info.st_gid);    printf ("Preferred I/O block size:%ld bytes\n", (long) info.st_blksize);    printf ("File Size:%lld bytes\n", (Long Long) info.st_size);    printf ("Blocks Allocated:%lld\n", (Long Long) info.st_blocks);    printf ("Last Status change:%s", CTime (&info.st_ctime));    printf ("Last File access:%s", CTime (&info.st_atime));    printf ("Last File Modification:%s", CTime (&info.st_mtime)); Exit (exit_success);}

Execution Result:

[Email protected]:~/linux_program/list$./stat stat.cfile type;                  Regular Filei-node Number:              679622Mode:                       100644 (octal) Link count:                 1Ownership:                  uid=1000 gid= 1000Preferred I/O block size:   4096 bytesfile size:                  2102 bytesblocks Allocated:           8Last status change:         Wed Jul 23:26:20 2014Last file access:           Wed Jul 23:26:35 2014Last file modification:     Wed Jul 16 23:26:20 2014

The appendix is/usr/include/sys/stat.h source code:

/*-* Copyright (c) 1982, 1986, 1989 the Regents of the University. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, is permitted provided that the FOL lowing conditions * is met: * 1. Redistributions of source code must retain the above copyright * Notice, this list of conditions and the following disc Laimer. * 2. Redistributions in binary form must reproduce the above copyright * Notice, this list of conditions and the following D Isclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: *th Is product includes software developed by the University of *california, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * May is used to endorse or promote products Deriv Ed from this software * WithouT specific prior written permission. * * This software are provided by the REGENTS and CONTRIBUTORS "as is" and * any EXPRESS OR implied warranties, including  LIMITED to, the * implied warranties of merchantability and FITNESS for A particular PURPOSE * is disclaimed. In NO EVENT shall the REGENTS OR CONTRIBUTORS is liable * for any DIRECT, INDIRECT, incidental, special, exemplary, or CO Nsequential * Damages (including, but not LIMITED to, procurement of substitute GOODS * OR SERVICES; LOSS of Use, DATA, OR profits; or business interruption) * However caused and on any theory of liability, WHETHER in contract, STRICT * liability, OR TOR T (including negligence OR OTHERWISE) arising in any-the-out-of-the-use of this software, even IF advised of the Possibi Lity of * SUCH DAMAGE. * *@ (#) stat.h7.11 (Berkeley) 3/3/91 */struct stat{dev_tst_dev;/* Inode's device */ino_tst_ino;/* inode ' s number */mode_ts t_mode;/* inode Protection mode */nlink_tst_nlink;/* number of hard links */uid_tst_uid;/* User ID of the file ' s owner */gid_tst_gid;/* Group ID of the file ' s group */dev_tst_rdev;/* device type */off _tst_size;/* file size, in bytes */time_tst_atime;/* time of last access */longst_spare1;time_tst_mtime;/* time's last Da Ta modification */longst_spare2;time_tst_ctime;/* Time of last file status change */longst_spare3;longst_blksize;/* Optimal blocksize for I/O */longst_blocks;/* blocks allocated for file */u_longst_flags;/* user defined flags for file */u _longst_gen;/* file generation number */}; #defineS_ISUID0004000/* Set User ID on Execution */#defineS_ISGID0002000//Set G Roup ID on Execution */#ifndef _posix_source#defines_istxt0001000/* sticky bit */#endif #defines_irwxu0000700/* RWX Mask F  or owner */#defineS_IRUSR0000400/* R for Owner */#defineS_IWUSR0000200/* W for Owner */#defineS_IXUSR0000100/* X for Owner */#ifndef _posix_source#defines_ireads_irusr#defines_iwrites_iwusr#defines_iexecs_ixusr#endif#defines_ irwxg0000070/* RWX Mask for group */#defineS_IRGRP0000040/* R for Group * * #defineS_IWGRP0000020/* W for Group */#defineS_IXGRP0000010/* X for Group */#defineS_IRWXO0000007/  * RWX Mask for other */#defineS_IROTH0000004/* R for other */#defineS_IWOTH0000002/* W for other */#defineS_IXOTH0000001/* X for other */#ifndef _posix_source#defines_ifmt 0170000/* type of file */#defineS_IFIFO 0010000/* named pipe (FIFO) */#d EFINES_IFCHR 0020000/* Character Special * * #defineS_IFDIR 0040000/* directory */#defineS_IFBLK 0060000/* block Special */ #defineS_IFREG 0100000/* Regular */#defineS_IFLNK 0120000/* Symbolic link */#defineS_IFSOCK 0140000/* socket */#defineS_ ISVTX 0001000/* Save swapped text even after use */#define s_blksize512/* block size used in the stat struct *//* 0666 */# Definedeffilemode (s_irusr| s_iwusr| s_irgrp| s_iwgrp| s_iroth| S_iwoth) #endif #defines_isdir (M) ((M & 0170000) = = 0040000)/* Directory */#defineS_ISCHR (M) ((M & 0170000) = = 0020000)/* Char Special */#defineS_ISBLK (M & 0170000) = = 0060000)//Block Special */#definEs_isreg (M) ((M & 0170000) = = 0100000)//Regular file */#defineS_ISFIFO (M) ((M & 0170000) = = 0010000)/* FIFO */#ifnd  EF _posix_source#defines_islnk (M) ((M & 0170000) = = 0120000)/* Symbolic link */#defineS_ISSOCK (M) ((M & 0170000) = = 0140000)/* socket */#endif #ifndef kernel#include <sys/cdefs.h>__begin_declsmode_tumask __p ((mode_t)); intchmod __p ((const char *, mode_t)), Intfstat __p ((int, struct stat *)), Intmkdir __p ((const char *, mode_t)), Intmkfifo __p ((const C Har *, mode_t)); Intstat __p ((const char *, struct stat *)), #ifndef _posix_sourceintfchmod __p ((int, mode_t)), Intlstat __p ( (const char *, struct stat *)); #endif/* Not POSIX */__END_DECLS#ENDIF

"Linux C learn Stat" Get the properties of a file